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Stable Iodine Nutrition During Two Decades of Continuous Universal Salt Iodisation in Sri Lanka


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Universal salt iodisation (USI) was introduced in Sri Lanka in 1995. Since then, four national iodine surveys have assessed the iodine nutrition status of the population. We retrospectively reviewed median urine iodine concentration (mUIC) and goitre prevalence in 16,910 schoolchildren (6–12 years) in all nine provinces of Sri Lanka, the mUIC of pregnant women, drinking-water iodine level, and the percentage of households consuming adequately (15 mg/kg) iodised salt (household salt iodine, HHIS). The mUIC of schoolchildren increased from 145.3 µg/L (interquartile range (IQR) = 84.6–240.4) in 2000 to 232.5 µg/L (IQR = 159.3–315.8) in 2016, but stayed within recommended levels. Some regional variability in mUIC was observed (178.8 and 297.3 µg/L in 2016). There was positive association between mUIC in schoolchildren and water iodine concentration. Goitre prevalence to palpation was a significantly reduced from 18.6% to 2.1% (p < 0.05). In pregnant women, median UIC increased in each trimester (102.3 (61.7–147.1); 217.5 (115.6–313.0); 273.1 (228.9–337.6) µg/L (p = 0.000)). We conclude that the introduction and maintenance of a continuous and consistent USI programme has been a success in Sri Lanka. In order to sustain the programme, it is important to retain monitoring of iodine status while tracking salt-consumption patterns to adjust the recommended iodine content of edible salt.
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Nutrients 2020, 12, 1109; doi:10.3390/nu12041109
Stable Iodine Nutrition During Two Decades of
Continuous Universal Salt Iodisation in Sri Lanka
Renuka Jayatissa
Jonathan Gorstein
Onyebuchi E. Okosieme
ohn H.
and Lakdasa D. Premawardhana
Department of Nutrition, Medical Research Institute, Danister De Silva Mawatha, Colombo 8, Sri Lanka
University of Washington, Department of Global Health, Seattle, WA 98195, USA; (J.G.)
Centre for Endocrine and Diabetes Sciences and Thyroid Research Group, C2 Link Corridor, University
Hospital of Wales, Heath Park, Cardiff CF14 4XN, UK; (O.E.O.); (J.H.L.); (L.D.P.)
* Correspondence:; Tel.: +94-777-788-444
Received: 23 March 2020; Accepted: 9 April 2020; Published: 16 April 2020
Abstract: Universal salt iodisation (USI) was introduced in Sri Lanka in 1995. Since then, four
national iodine surveys have assessed the iodine nutrition status of the population. We
retrospectively reviewed median urine iodine concentration (mUIC) and goitre prevalence in 16,910
schoolchildren (6–12 years) in all nine provinces of Sri Lanka, the mUIC of pregnant women,
drinking-water iodine level, and the percentage of households consuming adequately (15 mg/kg)
iodised salt (household salt iodine, HHIS). The mUIC of schoolchildren increased from 145.3 µg/L
(interquartile range (IQR) = 84.6–240.4) in 2000 to 232.5 µg/L (IQR = 159.3–315.8) in 2016, but stayed
within recommended levels. Some regional variability in mUIC was observed (178.8 and 297.3 µg/L
in 2016). There was positive association between mUIC in schoolchildren and water iodine
concentration. Goitre prevalence to palpation was a significantly reduced from 18.6% to 2.1% (p <
0.05). In pregnant women, median UIC increased in each trimester (102.3 (61.7–147.1); 217.5 (115.6–
313.0); 273.1 (228.9–337.6) µg/L (p = 0.000)). We conclude that the introduction and maintenance of
a continuous and consistent USI programme has been a success in Sri Lanka. In order to sustain the
programme, it is important to retain monitoring of iodine status while tracking salt-consumption
patterns to adjust the recommended iodine content of edible salt.
Keywords: iodine schoolchildren; urine iodine; goitre; iodised salt; water iodine; iodine pregnant
1. Introduction
Iodine is a micronutrient that primarily acts through the thyroid gland and its two hormones
(thyroxine and triiodothyronine), and it is vital to the integrity of many physiological functions in the
human body [1,2]. Iodine deficiency may affect multiple aspects of human development (including
intrauterine physical and neurological development), linear growth, and physiological organ
function. Organs such as the brain and nervous system are particularly vulnerable in their formative
stages during intrauterine life [1,2]. Fortunately, iodine deficiency is relatively easy and inexpensive
to prevent through universal iodisation of all edible salt. This is a pure food-chain effect, beginning
with soil erosion and leading to environmental iodine deficiency, and a lack of iodine sources in our
typical diet. Iodised salt was first introduced in Switzerland in 1922 [2,3] and has been used in many
previously iodine-deficient countries with good results [4]. The restoration of iodine sufficiency in
many of these countries has been a major public-health triumph facilitated by the United Nations
Children's Fund (UNICEF), World Health Organisation (WHO), and International Council of Control
Iodine Deficiency Disorders (ICCIDD, now named Iodine Global Network (IGN)). Statutory
Nutrients 2020, 12, 1109 2 of 10
regulations enforcing universal salt iodisation (USI) were implemented by regulatory authorities in
each country [5]. Sri Lanka is one such country that has successfully adopted a USI programme since
History of Iodine Deficiency and Its Management in Sri Lanka
Bennet and Pridham first referred to the existence of endemic goitre along the coast of Galle in
the southern province of Sri Lanka in 1849 [6]. However, the link between poor iodine consumption
and endemic goitre was first recognised only in the 20th century in a WHO study that confirmed high
goitre rates, an iodine-poor diet, and low iodine concentrations in drinking water in 1950 [7].
Mahadeva and his group in 1960 identified a “goitre belt” extending across the western, central,
southern, sabaragamuwa, and uva provinces in Sri Lanka [8]. The high annual rainfall in these
regions led experts to believe that iodine was “leeched” from the soil, leading to iodine deficiency.
At that stage, almost no goitre had been identified in the northern, eastern, and north-western
provinces [9]. However, in 1986, Fernando et al. described a high goitre rate of 18.8% in
schoolchildren in 17 of 24 districts in Sri Lanka—a variable prevalence of 6.5% in the Matale district
and 30.2% in the Kalutara district [10]. This study used palpation as the method of goitre assessment,
and was the first to recognise iodine deficiency as a major public-health problem.
USI was introduced nationwide by the government in 1995 by statutory regulation [11]. This
legislation banned the sale of non-iodised salt for human consumption, thus ensuring access to
iodised salt to all consumers in the country. Potassium iodate was used as the vehicle of iodine
supplementation, and added to salt at an optimal concentration of 50 ppm at producer level and 25
ppm at consumer level. The national reference laboratory for monitoring USI was established at the
Medical Research Institute (MRI) in 2000 with the aid of UNICEF. This laboratory has the dual role
of monitoring USI and of assessing its clinical impact by performing periodic national iodine surveys
(NISs). External quality control is linked to the EQUIP programme of the Centers for Disease Control
(CDC), Atlanta, Georgia, USA [12].
We review and describe the iodine-nutrition status in Sri Lanka by utilising serial datasets from
the four national iodine surveys carried out by the MRI between 2000 and 2016. We assessed the
success of USI in Sri Lanka in relation to global indicators of population iodine status, i.e., median
urine iodine concentration (mUIC), total goitre prevalence rates (TGRs), and household salt iodine
(HHIS) consumption.
2. Methods
2.1. Available Data Sources for Analysis
mUIC, TGRs, and HHIS were available for analysis from 4 national iodine surveys (NISs)
between 2000 and 2016—NIS2000, NIS2005, NIS2010, and NIS2016 [13–16]. These NIS used a two-
stage stratified cluster-sampling technique as specified by the WHO, UNICEF, and IGN [17,18].
During each NIS, the same team of field investigators visited all nine administrative provinces of the
country to detect goitres by palpation, and collected urine from 6–12-year–old schoolchildren, and
salt from their households and drinking-water samples from the household or school locality. Figure
1 illustrates the map of Sri Lanka demarcating 9 provinces. All four national studies were carried out
to ascertain provincial variation. A total of 16,910 schoolchildren of 6–12 years of age were studied in
the four surveys and included in the final analysis (Table 1). Furthermore, we had available data for
analysis from the national micronutrient study in pregnant women in 2015 (MNSPM2015) (Table 2)
Nutrients 2020, 12, 1109 3 of 10
Figure 1. Map of Sri Lanka demarcating nine provinces.
Table 1.
Median urine iodine concentration (mUIC), goitre prevalence, and household salt iodine
consumption in schoolchildren aged 6–12 years in 2000–2016. TGR, total goitre prevalence rate; HHIS,
household salt iodine; IQR, interquartile range.
Surveys UIC (µg/L)
HHIS (%)
% < 50
Median (IQR)
% <5 5–14.9 15–30 >30
(n = 5000) 1.6 232.5 (159.3–315.8) 1.9 3.1 18.4 63.5 15.0
(n = 7401) 6.7 163.4 (99.1–245.1) 4.4 4.6 27.1 52.5 16.1
(n = 1879) 7.4 154.4 (90.3–252.6) 3.8 0.0 8.7 47.7 43.5
(n = 2628) 2.7 145.3 (84.6–315.8) 18.0
p = 0.000. (- No data)
Table 2. Median UIC in pregnant women in three trimesters (national micronutrient study in
pregnant women in 2015, NNMSPM2015).
Trimesters UIC (µg/L) No
Period of Amenorrhea (POA) % <50
Median (IQR)
First trimester
(≤12 weeks of POA) 17.0 102.3 (61.7–147.1) 447
Second trimester
(13–28 weeks of POA) 6.2 217.5 (115.6–313.0) 339
Nutrients 2020, 12, 1109 4 of 10
Third trimester
(>28 weeks of POA) 0.0 273.1 (228.9–337.6) 176
Overall 10.1 157.7 (91.2–256.4) 962
p = 0.000.
2.2. Indicators of Population Iodine Status
Three primary indicators of population iodine status were considered, and we used the
methodology described below to assess the outcomes of the USI programme: (i) mUIC was measured
by ammonium persulfate digestion with spectrophotometric detection of the Sandell–Kolthoff
reaction in a laboratory certified by the EQUIP programme [20–22]; (ii) TGR—the grading of goitres
was done by palpation by the same team utilising the classification recommended by the WHO,
UNICEF, and IGN [3,18]: (a) “no goitre”—thyroid not palpable or visible; (b) “goitre present”—
thyroid palpable not visible or palpable and visible; and (iii) iodine content in salt: titration method
to measure the iodine content of salt certified by a regional iodine laboratory [3,18]. Geographical
location (province), iodine in drinking water, and household salt were measured to estimate their
influence on optimal iodine consumption. Iodine levels in drinking water at the household level and
school localities were tested using ammonium persulfate oxidation [20].
3. Data Analysis
The following definitions were used for classifying population iodine nutrition status [22]. (i)
Median UIC: (a) adequate mUIC—150–299 µg/L (pregnant women) and 100–299 µg/L
(schoolchildren); (b) excessive mUIC—≥300 µg/L; and (c) iodine sufficiency—<20% samples should
have mUIC of <50 µg/L. (ii) Household salt iodine (HHIS) content: we classified salt iodine content
as follows. (a) <5 mg/kg—non-iodised; (b) 5–14.9 mg/kg—inadequately iodised; (c) 15–30 mg/kg—
adequately iodised; and (d) >30 mg/kg—over-iodised. (iii) Iodine content in drinking water: iodine
in drinking water was classified as follows. (a) <5 mg/kg—no iodine; (b) 5–14.9 mg/kg—low iodine;
(c) 15–30 mg/kg—moderate iodine; and (d) >30 mg/kg—high iodine [23,24]
Statistical analysis was performed using SPSS (IBM version 24). Data that were not normally
distributed were expressed as median and interquartile range (IQR) unless otherwise stated. The
Mann–Whitney U–test was used to compare data between the two groups. The Kruskal–Wallis test
(nonparametric analysis of variance (ANOVA)) was used to assess the significance of differences
between more than two groups. Categorical variables were analysed using the chi-squared test for
trend; a p–value of <0.05 was considered statistically significant.
4. Results
(i) mUIC was consistently in the adequate or iodine-sufficient range in all four national iodine
surveys of 2000–2016. There has been a significant increase in mUIC, but still within the adequate
range in surveys between 2000 (145.3 (84.6–240.4)) and 2016 (232.5 (159.3–315.8)); p = 0.000). There has
also been a significant reduction in the percentage of schoolchildren with mUIC < 50 µg/L (2.7% in
2000 vs 1.6% in 2016; p = 0.000). As shown in Table 2, the mUIC of pregnant women was also in the
adequate or iodine-sufficient range (157.7 (228.9–337.6) µg/L) at the national level, and in the second
and third trimesters 217.5 (115.6–313.0), and 273.1 (228.9–337.6) µg/L; p < 0.000). Table 3 shows there
is regional variability in mUIC levels in children of 6–12 years of age (297.3 vs. 178.8 µg/L in 2016; p
= 0.000). It was significantly higher in the northern and north–central provinces when compared to
the rest of the country since 2005.
Table 3. Regional variations of key indicators of population iodine nutrition in 2000–2016.
Median Iodine
Content in Salt
(IQR; mg/kg)
Iodised HHIS (%)
Median UIC (IQR)
Nutrients 2020, 12, 1109 5 of 10
96.1 70.0 71.6
94.4 66.7 70.2
97.4 74.0 91.0
74.3 48.3 83.6
90.6 78.5 91.2
93.6 60.6 68.1
North Central
90.1 67.7 64.1
94.6 72.9 81.5
a 32.0 22.2 22.2 92.4 70.7 82.0 194.4 109.0 121.1 217.5
Nutrients 2020, 12, 1109 6 of 10
Sri Lanka
91.4 67.6 78.0
p = 0.000.
(ii) There was significant reduction in TGR by palpation between surveys done in 2000 (18.0%)
and 2016 (1.9%; p = 0.000; Table 1).
(iii) The iodine content of HHIS was only measured since 2005, and since that time, over 95% of
all HHIS has contained at least some iodine (>5 mg/kg). The percentage of HHIS with adequate iodine
concentrations (defined as 15–30 mg/kg) showed a significant increase—47.7% in NIS2005 vs. 63.5%
in NIS2016 (p = 0.000). Furthermore, only 3.1% had a salt content of <5 mg/kg (non-iodised) in the last
survey in 2016. The prevalence of over-iodised salt (>30mg/kg) significantly fell from 43.5% in 2005
to 15.0% in 2016 (p = 0.000; Table 1). HHIS was less than 90% at the national level, and in all provinces
in 2010 and 2016 except for the central and eastern provinces. In 2016, the interprovincial difference
of median iodine content in HHIS was between 18.0 and 27.5 mg/kg (Table 3).
(iv) Median iodine content of drinking water was 33.4 (12.3–66.8) µg/L. Wide variation was
observed between provinces (8.3 (4.6–29.0) vs 75.5 (48.4–102.5) µg/L; p = 0.000) in the uva and north–
central provinces, respectively (Table 4).
Table 4. Regional variations of median iodine content of drinking water in 2016.
Province No Median (IQR) µg/L
Western 67 15.6 (4.1–29.1)
Southern 70 19.1 (15.3–29.9)
Central 68 18.0 (5.7–44.6)
Northern 78 53.4 (28.9–79.4)
Eastern 189 33.3 (17.0–69.6)
North Western 122 39.9 (9.4–61.4)
North Central 170 75.5 (48.4–102.5)
Uva 62 8.3 (4.6–50.4)
Sabaragamuwa 108 31.3 (15.1–50.4)
Sri Lanka 934 33.4 (12.3–66.8)
Note: p = 0.000.
Figure 2 provides a graphical representation of the data on median UIC of children aged 6–12
years in 2016, stratified by the iodine content in HHIS and in drinking water. These data are
noteworthy since the mUIC was within the optimal range in all subgroups, including those
households of which the iodine content in HHIS was <5 ppm or in the range of 5–14.9 ppm,
suggesting that the consumed iodine in HHIS is not the exclusive diet source of iodine. There was a
significant increase in median UIC with increasing iodine concentrations in drinking water (p = 0.000).
Nutrients 2020, 12, 1109 7 of 10
Figure 2. Median urine iodine concentration (IQR) and its relationship with iodine concentrations in
household salt and drinking water in school children aged 6–12 years in 2016.
5. Discussion
USI was first implemented in Sri Lanka in 1995. We demonstrated in this retrospective review
of data from four national iodine surveys of over more than two decades of continuous salt iodisation
that (i) mUIC has consistently been in the adequate range with a sequential increase within safe and
recommended limits; (ii) the goitre-prevalence rate to palpation in children between 6–12 years
significantly decreased between 2000 and 2016 (18.0% to 1.9%; p = 0.000); and (iii) the percentage of
adequately iodised household salt samples significantly increased during this period (47.7% in 2005
vs. 63.3% in 2016; p = 0.000), and its household consumption remains satisfactory (Tables 1 and 3).
These indices of population iodine nutrition favourably reflect the success of the USI programme
enforced by successive governments of Sri Lanka, having adequate iodine status at the national level
and in most provinces (Tables 1 and 3). Furthermore, there has been a recurrence of iodine deficiency
in several countries where iodine-deficiency disorders (IDDs) were eliminated with USI because of
inadequate monitoring of their USI programmes [25–29]. Strict monitoring is essential in sustaining
proper iodine nutrition in countries that adopt USI [28].
However, there is a need for caution. (a) The median UIC of pregnant women is only marginally
above the recommended cut off of 150 µg/L, and iodine-insufficient in the first trimester (102.3 (61.7–
147.1) µg/L (Table 2)). There was a remarkable improvement in the iodine status of pregnant women
compared to 2011 (113.7 µg/L) [30]. There was also a significant minority of pregnant women (nearly
10%) who had a median UIC of <50 µg/L. This is an important population group, and inadequate
iodine delivery to this group may have important long-term consequences, particularly regarding
the intrauterine development of the brain, central nervous system, and physical growth [29]. (b) The
median UIC of schoolchildren in the northern and north–central provinces in 2016 approached 300
µg/L. In these two areas at risk of iodine excess, iodine content in drinking water was the highest
among those provinces (Table 4). Other countries’ experience with high iodine content in drinking
water should be reviewed [31,32]. (c) Some regional variability in mUIC was observed over the course
of the programme, but in the most recent survey, the range was between 178.8 and 297.3 µg/L, all
within the optimal range. The reasons for regional variability of median UIC have not been
investigated in detail, but need to be noted (Table 2). There is a clear need, therefore, to closely
monitor these groups in the future, with periodic well-designed and more elaborate studies.
However, we acknowledge that these UIC assessments were done on single “spot” samples of urine
Nutrients 2020, 12, 1109 8 of 10
and may not be truly representative of the iodine-nutrition status of each individual in these
communities [28].
We also showed that the supervision and monitoring of salt iodisation has improved over two
decades of USI. The percentage of samples delivering adequate levels of salt at the consumer level
(i.e., 15–30 mg/kg) increased from 47.5% in NIS2005 to 63.3% in NIS2016 (p = 0.000), while at the same
time, the percentage of over-iodised salt samples has significantly decreased (p = 0.000; Table 1). The
percentage of households using adequately iodised salt was less than 90% (the WHO goal for USI) at
the national level and in seven out of nine provinces (Table 3). However, it showed that the median
HHIS content in provinces was between 18.0 and 27.5 mg/kg, confirming that household iodised salt
was providing a significant amount of iodine to the diet [33].
Despite a <90% of households consuming adequately iodised salt, there has been an increase in
mUIC, and some provinces in the country consistently showed a high level of mUIC. Daily mean per
capita salt intake of Sri Lankans was reported as 8.3 g (CI: 7.9, 8.8) in 2012 [34]. We also need to be
aware of the contribution of other sources of iodine contributing to population iodine nutrition, e.g.,
drinking water, processed foods, or condiments, which are being manufactured with iodised salt, as
well as some iodine in foods. Our results indicated a positive association between iodine status in
schoolchildren and water iodine concentration, although the major contributor to iodine intake is
iodised salt in the diet (Figure 2). In fact, over 95% of households have consistently had access to
iodised salt since 2005. A similar contribution was observed in other countries [24,32]. There is a need
to adjust the recommended level of HHIS, and to explore the iodine supply through different dietary
sources and the geological assessment of soil iodine content for future monitoring.
IGN/UNICEF recommends that the optimal iodine intake, as measured by the median UIC for
school-age children, should be <300 µg/L, while the mUIC among pregnant women should be <500
µg/L [22]. Thus, the current salt-iodisation programme is having its desired impact and not placing
the Sri Lankan population at risk for iodine excess, as described in the previous study [33]. The salt-
iodisation programme needs to be consistently monitored so that the level of iodine in all edible salt,
including that used at the household level as well as in processed foods and condiments, leads to an
optimal intake. As salt-reduction efforts are implemented, there may be a decline in overall salt
consumption, in which case the government may need to accordingly adjust the recommended salt
iodine level to ensure that public-health strategies of iodine-deficiency prevention, salt reduction,
and reduction in NCDs are realised.
Despite adequate iodine nutrition among schoolchildren, iodine nutrition among pregnant
women remains just above the cut-off levels in the country. There is a need to focus on pregnant
women for continuous monitoring while sustaining the iodised-salt programme.
This study has several strengths. (a) Data availability from a large number of 6–12-year-old
schoolchildren (16,910 in total); (b) uniform methodology for UIC assessments over the period of
review in a single laboratory with stringent external quality control; (c) permanent health staff used
as a single team in all four studies and goitre palpation; (d) minimising variability in urine- and salt-
assay methodology using the same protocols developed by the UNICEF, WHO, and IGN. However,
the unavailability of pre-USI data for comparison was an inherent shortcoming of this study.
6. Conclusions
The iodine nutrition of the population has remained optimal and stable in Sri Lanka during more
than two decades of continuous salt iodisation after its introduction in 1995. However, we
recommend the close and careful monitoring of pregnant women and schoolchildren in view of the
data we presented. The delivery of salt to consumers has improved and is adequate in the majority.
The contribution of dietary sources other than salt needs to be assessed in well-planned studies.
Author Contributions: R.J. analysed datasets; R.J., J.G., L.D.P., J.H.L., and O.E.O. conceptualised, designed, and
wrote the paper. All authors read the manuscript, made a substantial contribution to the revision, and approved
the final manuscript. All authors have read and agreed to the published version of the manuscript.
Acknowledgments: We thank the staff of the Department of Nutrition, Medical Research Institute, Ministry of
Health, Sri Lanka for conducting the national survey, and all the participants of the study. We would like to
Nutrients 2020, 12, 1109 9 of 10
thank Dulitha Fernando, Pierre Boudex, and the late Meliyanthi Gunathilaka for supporting us in every step.
Adikari, Morina Hossein, Aberra Bekele, Moazzem Hossaine from UNICEF, Colombo and Chandrakant Pandav
for all their support from the beginning. This research received no specific grant from any funding agency in the
public, commercial, or not-for-profit sectors.
Conflicts of Interest: The opinions expressed are those of the authors and do not necessarily reflect the views of
the institutions with which they are affiliated. The authors declare that there is no conflict of interest.
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... Surveys during this period have consistently shown that over 95% of households were using salt with at least some iodine (>5 mg/kg). In 2016, 78% of households were using salt with 15 mg/kg iodine or above and the median salt iodine content across all households was 21mg/kg, with interprovincial differences ranging from 18 to 28 mg/kg [5,6]. The same 2016 survey included assessment of iodine status among 5,000 children 6 to 12 years of age and indicated adequate iodine status among this group nationally, median urinary iodine concentration (MUIC) 233 μg/L, and across the provinces, MUIC ranged from179 μg/L in Uva province to 297 μg/L in the Northern province. ...
... Yet this level of intake would only contribute to three quarters of the RNI for iodine, which is the average intake considered sufficient to meet the nutrient requirements of nearly all (97-98%) of healthy non-pregnant adults in the population [15]. However, despite iodine intake from these sources of iodized salt seeming insufficient to meet the needs of all population groups, particularly in North Western and North Central provinces where intake estimates donot meet the EAR for iodine; survey evidence indicates optimal iodine status among school age children in all provinces and among pregnant women at the national level [5,7]. This suggests that there are other sources of iodine in the diet, for example, iodized salt in other processed foods and foods made outside the home that were not included in this assessment. ...
... This suggests that there are other sources of iodine in the diet, for example, iodized salt in other processed foods and foods made outside the home that were not included in this assessment. It is also known that iodine in drinking water contributes to intake in some areas of the country [5]. Based on the demonstrated significant current iodine intake from household and food industry iodized salt and on data showing adequate iodine nutrition among the population, the current salt iodine standards (15-30 mg/kg) appear adequate to meet dietary needs and sustain optimal iodine intake among all age groups [5]. ...
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In Sri Lanka dietary patterns are shifting towards increased consumption of industrially processed foods (IPF). This study aimed to estimate the contribution of IPF to salt and iodine intake and assess the possible impact of salt reduction on iodized salt intake. The assessment was conducted using guidance published by the Iodine Global Network. National nutrition and household income expenditure surveys were used to estimate adult per capita consumption of household salt and commonly consumed salt-containing IPF. Industry and laboratory data were used to quantify salt content of IPF. Modelling estimated the potential and current iodine intake from consumption of household salt and using iodized salt in the identified IPF. Estimates were adjusted to investigate the likely impact on iodine intake of achieving 30% salt reduction. IPF included were bread, dried fish and biscuits, with daily per capita consumption of 32g, 10g and 7g respectively. Daily intake of household salt was estimated to be 8.5g. Potential average national daily iodine intake if all salt in these products was iodized was 166μg. Estimated current daily iodine intake, based on iodization of 78% of household salt and dried fish being made with non-iodized salt, was 111μg nationally, ranging from 90 to 145μg provincially. Estimated potential and current iodine intakes were above the estimated average requirement of 95μg iodine for adults, however, current intake was below the recommended nutrient intake of 150μg. If the 30% salt reduction target is achieved, estimated current iodine intake from household salt, bread and biscuits could decrease to 78μg. The assessment together with data for iodine status suggest that current iodine intake of adults in Sri Lanka is adequate. Recommendations to sustain with reduced salt intake are to strengthen monitoring of population iodine status and of food industry use of iodized salt, and to adjust the salt iodine levels if needed.
... According to the Iodine Global Network [43], all countries involved in this study appear to have adequate iodine intakes at the population level. However, irrespective of the implementation of USI, certain segments of the populations are considered having or being at risk of an insufficient iodine status for various reasons, such as food choice driven by commercial forces and marketing as well as changes in food consumption habits or by the free trade/single market in the EU [27,[42][43][44][45][46][47][48][49]. For instance, in Poland [50], Slovenia [51] and Sri Lanka [49], mandatory iodisation of salt for household consumption is required by law, whereas in Taiwan [48], Greece and Germany [44], salt iodisation is voluntary and thus both iodised and non-iodised salts are accessible on the market. ...
... However, irrespective of the implementation of USI, certain segments of the populations are considered having or being at risk of an insufficient iodine status for various reasons, such as food choice driven by commercial forces and marketing as well as changes in food consumption habits or by the free trade/single market in the EU [27,[42][43][44][45][46][47][48][49]. For instance, in Poland [50], Slovenia [51] and Sri Lanka [49], mandatory iodisation of salt for household consumption is required by law, whereas in Taiwan [48], Greece and Germany [44], salt iodisation is voluntary and thus both iodised and non-iodised salts are accessible on the market. Indeed, the fact that non-iodised salt may be legally sold in countries of the European Union [52], has been suggested to pose a risk of inadequate iodine intake to those who deliberately choose only noniodised salt in Slovenia [51]. ...
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Background: Strategies to reduce salt intake are encouraged to be implemented in parallel with those that aim to ensure iodine adequacy at the population level. The aim of the present study was to assess and compare knowledge, attitudes and behaviours related to salt and iodine among students in Europe and Asia. Methods: A multicentre cross-sectional study was conducted with 2459 university students in total (42.7% males, median age 21 years) from four countries in Europe and two countries in Asia. Data were collected with the use of a self-administered questionnaire, and univariate and multivariate statistical analyses were performed to explore any association between variables. Results: Only 6.5% of all participants knew the correct salt recommendations. Nearly a quarter of them (24.4%) found salt recommendations confusing and/or contradictory. There were significant differences between European and Asian participants, with those from Europe being better informed about salt recommendations, but significantly less knowledgeable about iodine. The reported frequency of use of salt and salt-containing sauces either at the table or for cooking, as well as knowledge about ways to reduce salt intake among those who indicated to make conscious efforts to do so, differed significantly between countries. Significant differences between countries were also observed with respect to the type of salt used, with about one third of all participants (34%) not being aware of the kind of salt they used. Conclusion: The results of this survey highlight serious salt- and iodine-related knowledge gaps among university students in Europe and Asia. Raising awareness and conducting information campaigns is needed to promote changes in behaviour that would result in a reduction of salt intake and conscious use of iodised salt at the individual level.
... Salt iodization is the best strategy to control iodine deficiency, and it is also one of the most cost-effective ways to contribute to economic and social development. Some countries and regions around the world, including China, have adopted universal salt iodization (USI) to control iodine deficiency and achieve remarkable results [3][4][5][6][7]. The USI policy was implemented in China from 1994. ...
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China has issued the “Reform Plan of the Salt Industry System” in 2016 and it is necessary to attach the importance to the changes of iodine nutritional status of those people who might consume non-iodized salt for a long time. Forty-six elderly subjects were recruited and replaced iodized salt with non-iodized salt for 6 months. Urine iodine concentration (UIC), dietary iodine intake, thyroid function, thyroid B-ultrasound, and plasma iodine were monitored during the follow-up period. The median dietary iodine intakes of the baseline, the 1st, 2nd,3rd, 4th, and 6th month were 255.3 µg/d, 183.6 µg/d, 164.6 µg/d, 179.2 µg/d, 139.4 µg/d, and 146.9 µg/d, respectively. The median UIC of baseline and follow-up was 155.7 (111.0–263.1) µg/L and 69.7(36.7–119.8) µg/L, respectively. The proportion of urinary iodine less than 50 g/L at the baseline and follow-up was 3.0 (0 ~ 8.9)% and 36.0 (33.1 ~ 38.9)%, respectively. Dietary iodine intake had a significant correlation with urine iodine. Six subjects (15.4%) had abnormal thyroid function. Three subjects (7.7%) had first-onset new nodules or enlarged solid nodules and the median UIC of these three subjects during the follow-up period was 39.8 µg/L, which was significantly lower than that of other subject (74.0 µg/L). T4 and T3 had a significant correlation with plasma iodine. The importance of monitoring and evaluating iodine nutrition of people consuming non-iodized salt should be stressed to prevent the potential poor iodine nutrition and iodine deficiency diseases.
... Across regions, data suggested low prevalence of iodine deficiency and/or goitre overall, due to implementation of effective salt iodisation programmes ( Table 2). For example, nationally representative longitudinal data from Sri Lanka showed a reduction in the prevalence of iodine deficiency (2·7 % to 1·6 %) and goitre (18·0 % to 1·9 %) between 2000 and 2016 (52) . However, there was variation within and between regions, with both the lowest (0·0 % in Indonesia) (53) and the highest (88·1 % in Papua New Guinea) (54) prevalence of iodine deficiency documented in EAP region. ...
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Objective To summarise available evidence on the nutritional status of school-age children and adolescents (5–19 years) from seven global regions, and on interventions implemented to improve malnutrition in this population. Design Findings were compiled from seven scoping literature reviews, including data from low- and middle-income countries (LMICs) within the following UNICEF-defined global regions: East Asia and Pacific (EAP); Europe and Central Asia (ECA); South Asia (SA); West and Central Africa (WCA); Eastern and Southern Africa (ESA); Middle East and North Africa (MENA); and Latin America and the Caribbean (LAC). Results A double burden of malnutrition was evident across the world regions reviewed: stunting, thinness, anaemia and other micronutrient deficiencies persisted, alongside rising overweight and obesity prevalence. Transitions towards diets increasingly high in energy-dense, processed and micronutrient-poor foods were observed. Evidence from intervention studies was limited, but suggested that providing multiple micronutrient-fortified foods or beverages at school may effectively target micronutrient deficiencies and facilitate weight gain in undernourished populations. Interventions to prevent or manage overweight and obesity were even more limited. There was minimal evidence of using novel technological approaches to engage school-age children and adolescents, or of involving them in designing interventions. Conclusion The limited data available on nutrition of school-age children and adolescents is neither standardised nor comparable. Consensus on methods for assessing nutritional status and its determinants for this age group is urgently needed to set targets and monitor progress. Additionally, strategies are required to ensure that nutritious, safe and sustainable diets are available, affordable and appealing.
... Среди недавно опубликованных работ стоит отметить, к примеру, ситуацию на Шри-Ланке, где всеобщее йодирование соли было введено в 1995 г. При проведении массового исследования (16 910 школьников) распространенность зоба при пальпации была значительно снижена -с 18,6% до 2,1% (р<0,05) [21]. ...
Background: The level of iodine consumption by the population largery determines the spectrum of thyroid pathology. To date, in the Russian Federation, iodine-deficiency disorders (IDD) occupy a leading position in the structure of all thyroid diseases. Chronic ID leads to adverse health consequences and significant economic costs for their elimination on a national scale. However, the spectrum of thyroid pathology is not limited to the problem of ID, and the study of other thyroid diseases is also of interest. Aims: to assess the dynamics of prevalence and incidence of IDD and other thyroid diseases in the entire population of the RF for the period 2009-2018, using official state statistics. Materials and methods: the main epidemiological indicators (incidence and prevalence) of thyroid diseases in the entire population of the RF were analyzed using official state statistics. The analyzed period is 2009-2018. There was no medical intervention. To assess the dynamics of prevalence and incidence, a linear regression models were constructed, the slope of the trend line was calculated. Results: the data were analyzed in accordance with the structure of diseases presented in the statistical reporting: goiter, thyroiditis, hypothyroidism, thyrotoxicosis, congenital iodine deficiency syndrome. For the ten-year period 2009-2018 there is a statistically significant increase in the prevalence of various forms of goiter, thyrotoxicosis, congenital iodine deficiency syndrome in the entire population of the Russian Federation. During the observation period, an increase in the incidence of thyrotoxicosis was revealed. With regard to the incidence of congenital iodine deficiency syndrome, only an upward trend was revealed. Despite the fact that during the observation period the number of new cases of various forms of goiter decreased, the prevalence of goiter among the population of the Russian Federation remains high: 1.2% of the population by January 1, 2019. with the growth of autoimmune pathology, improvement of the level of diagnosis, and also, in some cases, with overdiagnosis (for example, when diagnosing autoimmune thyroiditis in individuals with asymptomatic carriage of antithyroid antibodies). The current approaches to iodine prophylaxis are not effective enough. Conclusions: the results of the analysis indicate mainly an increase in the high prevalence of thyroid pathology among the population of the RF against the background of regional events. The problem of ID remains unresolved, which dictates the need to introduce universal mandatory salt iodization in the territory of the RF.
... In this issue, we provide an update on the iodine status of the general population in different countries of the world, including Moldovia [21], Korea [22], the United States [23,24], Sri Lanka [25], Finland [26] and Italy [27,28], with a special focus on newborns [24] and pregnant women [24,26], which are the most vulnerable categories. Importantly, we have invited an international panel of endocrinologists to review the literature and to comment upon the effects of the most common nutraceuticals on thyroid function, based on the most recent in vitro and in vivo [29,30], as well as human, studies [31]. ...
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Iodine is a microelement that is naturally present in some foods, added to others, and available as a dietary supplement [...]
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Background Iodine status, including Iodine Deficiency (ID) of the children aged 12–59 months of Jaffna District, Sri Lanka, have never been studied. This study thus aimed to assess ID among children aged 12–59 months by monitoring the Urinary Iodine Concentrations (UIC), the prevalence of goitre, and the factors causing ID. Method A cross-sectional study was conducted among 846 children aged 12–59 months in Jaffna District, Sri Lanka. Sociodemographic characteristics and other factors were collected using an interviewer-administered questionnaire. Dietary pattern of children was obtained using semi-quantitative food frequency questionnaire. We performed urinary iodine estimation and physical examinations to detect the goitre, according to the World Health Organization criteria. A multivariate logistic linear regression model was used to identify the factors that causing ID. Result The median UIC was 146.4 μg/L (interquartile range = 112.6–185.3 μg/L). Based on the UIC (<100 μg/L), 17.8% had ID, of which 15.7% and 2.1% had mild and moderate ID. The mean consumption of iodine from food was 128.7 (±20.2) μg/day. Gender variation had no influence on ID (p>0.05). Median UIC was significantly associated with living area, wealth status, type of drinking water, and method of iodized salt usage. A higher percentage of ID was significantly associated with younger age [AOR 2.32 (95% CI: 1.31–4.10)], urban area [AOR 1.94 (95% CI 1.27–2.96)], inland regions [AOR 3.20 (95% CI 1.85–5.55)], improper method of iodized salt usage [AOR 3.63 (95% CI: 1.38–9.56)], and low consumption of iodine-containing foods. The neck palpation revealed that only three children had goitre (0.4%). Conclusion This study revealed that high ID among the children in Jaffna children was due to improper usage of iodized salt, even though the iodized salt is freely available in the region, living area, and age, while the prevalence of goitre was not significantly identified as a public health problem.
Background: Sri Lanka introduced universal salt iodization (USI) in 1995 after which we demonstrated a high thyroglobulin antibody (TgAb) prevalence in 1998. However, it is unclear whether thyroid autoimmunity persists in the long term in populations exposed to sustained USI and whether such populations have an excess of thyroid dysfunction. We evaluated the prevalence of thyroid autoantibodies and dysfunction in Sri Lankan children and adolescents after more than two decades of sustained USI. Methods: We selected 10- to 18-year-old subjects of both sexes (randomized cluster sampling) from all 9 provinces of Sri Lanka in this cross-sectional study. Blood, urine, and anthropometric data were collected and thyroid ultrasound scans were performed. Validated statistical methods were used to derive local population-specific reference ranges for all thyroid parameters. We also measured urine iodine concentration (UIC), salt, and water iodine concentrations. Results: Blood and urine samples from 2507 and 2473 subjects respectively, and ultrasound scans from 882 subjects were analyzed. Population-derived upper limits for thyroid peroxidase antibody (TPOAb) and TgAb, and reference ranges for triiodothyronine, thyroxine, and thyrotropin (total and age-year-related groups) were significantly different from manufacturer's reference ranges. Using these derived ranges, the prevalence of TPOAb was 10.3% and TgAb was 6.4%. Of the TPOAb-positive subjects, TPOAb were of low concentration in 66.2% (1-3 times the upper limit of the reference range [ULRR]) and showed the strongest association with subclinical hypothyroidism (SCH) at the highest concentrations (>4 ULRR). The prevalence of SCH was 3%. Median UIC (interquartile range) was 138.5 μg/L (79.4-219.0) with regional variability, and median thyroglobulin was 8.3 ng/mL (4.1-13.5). Goiter prevalence was 0.6% and 1.93% (thyroid volume compared to age and body surface area, respectively). Salt and water iodine concentrations were satisfactory. Conclusions: Sri Lanka has safely and effectively implemented USI with good sources of iodine, leading to sustained iodine sufficiency over more than two decades. The early postiodization TgAb surge (42.1%) has settled (6.4%), and despite a persistently high TPOAb prevalence (10.3%), SCH prevalence remains low (3%). Further studies should be undertaken to monitor thyroid autoimmune dysfunction in Sri Lankan children, using age-specific, population-derived reference ranges.
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Background: Sodium intakes of different populations around the world became of interest after a
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Based on new evidence and lessons learned within the last decade, pregnant women may not receive adequate iodized salt where the coverage of universal salt iodisation is poor. World Health Organisation has stated this could jeopardize optimal brain development of the fetus. This study was aimed to assess the iodine status of pregnant women in Sri Lanka. A cross-sectional clinic based nationally representative study was conducted. Three randomly selected antenatal clinics from each province, 30 randomly selected pregnant women from each selected clinic were included in the study. A total of 739 pregnant women were studied and casual urine samples collected to estimate iodine levels. Median urinary iodine levels in pregnant women was 113.7 g/L, which is far below the WHO recommendation between 150 and 249 μg/L indicating inadequate iodine status of pregnant women in Sri Lanka. Urine iodine distribution indicated 61.3%, 21.7%, 15.2% and 1.8% of pregnant women had an inadequate, adequate, above requirement and excessive intake respectively. Urinary iodine concentration significantly decreased with advancing pregnancy. Inadequate iodine intake was evident in 47.4%, 60.2% and 68.8% of pregnant women in the first, second and third trimester respectively. In conclusion, there is an urgent need to identify a programme to provide adequate iodine to pregnant women to ensure optimum fetal brain development.
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This manual is intended for those involved the design and implementation of surveys to assess vitamin and mineral deficiencies, as well as the planning, implementation, analysis, and reporting of survey results. Included are the procedures and tools necessary to undertake a cross-sectional survey that will provide estimates of the prevalence of iron deficiency anemia, iodine and vitamin A deficiency. Such surveys are usually carried out periodically to provide information that should lead to advocacy and appropriate intervention strategies. When carried out sequentially, surveys can be used to track progress of prevention and control efforts over time. Information on the coverage of prevention and control programs (such as vitamin A capsule distribution, salt iodization, and flour fortification) are also included.
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Children born to women with low thyroid hormone levels have been reported to have decreased cognitive function. We conducted a randomized trial in which pregnant women at a gestation of 15 weeks 6 days or less provided blood samples for measurement of thyrotropin and free thyroxine (T(4)). Women were assigned to a screening group (in which measurements were obtained immediately) or a control group (in which serum was stored and measurements were obtained shortly after delivery). Thyrotropin levels above the 97.5th percentile, free T(4) levels below the 2.5th percentile, or both were considered a positive screening result. Women with positive findings in the screening group were assigned to 150 μg of levothyroxine per day. The primary outcome was IQ at 3 years of age in children of women with positive results, as measured by psychologists who were unaware of the group assignments. Of 21,846 women who provided blood samples (at a median gestational age of 12 weeks 3 days), 390 women in the screening group and 404 in the control group tested positive. The median gestational age at the start of levothyroxine treatment was 13 weeks 3 days; treatment was adjusted as needed to achieve a target thyrotropin level of 0.1 to 1.0 mIU per liter. Among the children of women with positive results, the mean IQ scores were 99.2 and 100.0 in the screening and control groups, respectively (difference, 0.8; 95% confidence interval [CI], -1.1 to 2.6; P=0.40 by intention-to-treat analysis); the proportions of children with an IQ of less than 85 were 12.1% in the screening group and 14.1% in the control group (difference, 2.1 percentage points; 95% CI, -2.6 to 6.7; P=0.39). An on-treatment analysis showed similar results. Antenatal screening (at a median gestational age of 12 weeks 3 days) and maternal treatment for hypothyroidism did not result in improved cognitive function in children at 3 years of age. (Funded by the Wellcome Trust UK and Compagnia di San Paulo, Turin; Current Controlled Trials number, ISRCTN46178175.).
In recent decades, Sri Lanka has made substantial progress in reducing the burden of micronutrient deficiencies in children by the provision of vitamin A megadose and micronutrient supplementation programs for children of 6–23 months, along with universal iodization of salt. Consumption of voluntarily fortified foods by children was also considerably increased. The objective of our study here was to review such interventions, which are beneficial in childhood, and to assess the risk of toxicity due to excessive intakes of iron, vitamin A, and iodine. Our analysis was performed using data from two national micronutrient surveys, market surveys, and key informant interviews. Data on coverage, usage, and nutrient content of certain foods were compiled to gauge consumption of iron, vitamin A, and iodine among children. We found that the severity of anemia and vitamin A and iodine deficiencies declined from moderate‐to‐severe and that supplementation and fortification can lead to an excess of vitamin A that may cause toxicity, while iron and iodine deficiency appears to be no longer a public health concern in Sri Lanka. We recommend review and scaling back of national supplementation programs and monitoring of fortification initiatives to prevent micronutrient toxicity in the future.
Previous studies have reported an association between reduced thyroid function during pregnancy and impaired cognitive development in offspring. This finding suggests that antenatal screening and treatment of thyroid deficiency could be beneficial. However, routine antenatal screening for hypothyroidism in pregnant women is not recommended. This randomized controlled trial was designed to determine whether antenatal screening and treatment of thyroid deficiency before 20 weeks of gestation was associated with improved cognitive function of offspring at 3 years of age. All participants were pregnant women older than 18 years at a gestational age of less than 15 weeks 6 days with no known thyroid disease before antenatal screening. Before randomization, all participants had reduced thyroid function defined as a high thyrotropin level or a low free thyroxine (T4) level. Cognitive function was compared in the offspring of women treated for thyroid deficiency early in pregnancy (screening and treatment group) and children of women who were untreated (control group). Blood samples were obtained at a gestational age of ≤15 weeks 6 days for measurement of thyrotropin and free T4 levels. The measurements were performed immediately after collection of samples in the screened/treated group, whereas samples obtained from the control group women were stored, and measurements were performed shortly after delivery. A positive screening result was considered to be serum thyrotropin levels above the 97.5th percentile, free T4 levels below the 2.5th percentile, or both. Patients in the screened/treated group with positive results received levothyroxine at a dose of 150 μg/d. The intelligence quotient (IQ) at 3 years of age in children was measured by psychologists blinded to the group assignments. Similar proportions of women in the screening group (5%) and control group (4.6%) were classified as having positive results based on a high thyrotropin level or a low free T4 level. At the start of levothyroxine treatment, the median gestational age was 13 weeks 3 days; treatment was adjusted as necessary to achieve a target thyrotropin level of 0.1 to 1.0 mIU/L. There was no significant difference between the mean IQ scores of children at 3 years of age born to treated women and untreated women with reduced thyroid function (IQ: 99.2 in the screening group and 100.0 in the control group); the difference was 0.8 IQ points; with a 95% confidence interval of −1.1 to 2.6 (P = 0.40 with intention-to-treat analysis). An IQ of less than 85 was found in 12.1% in the screened/treated group and 14.1% in the control group (difference, 2.1% [95% confidence interval, −2.6 to 6.7; P = 0.39]). Similar results were found in analyses limited to the women who adhered to treatment. These findings show that routine antenatal thyroid screening of pregnant women and treatment of those early in pregnancy who had reduced thyroid function does not improve cognitive function in their children at 3 years of age.
Background/objectives: In Hebei province, China, over six million people are potentially exposed to excessive iodine through consumption of high iodine underground drinking water and consumption of iodized salt. The aim of this study is to evaluate the contributions of drinking water and iodized salt on children's iodine nutrition in one area of Hebei province in order to refine strategies to correct the excessive iodine intake in these areas. Subjects/methods: To investigate the relationships between iodine content in water, iodized salt and urinary iodine content (UIC) in children (8-10 years), we randomly sampled three towns with a known median water iodine (MWI) of 150-300 μg/l in Hengshui City, Hebei province and collected water, salt and urine samples. Results: The median UIC was 518.1 μg/l, the overall MWI was 247.0 μg/l, and 83% of children sampled were found to have urinary iodine concentrations higher than the WHO criterion of 300 μg/l. There was a significant and positive correlation between the median UIC of the children and the MWI in the 12 villages where the children lived (Spearman R=0.79, P=0.002), but the UIC was not significantly correlated with the median salt intake (MSI) (Spearman R=-0.17, P=0.6). A multiple linear regression analysis indicated that 68.7% of the variability in median UIC is associated with variability in MWI in the 12 villages. Conclusions: Iodine in drinking water was identified to be the key contributor to this excessive iodine in children indicating that in these areas, intervention should focus on providing alternative drinking water supplies.
Excessive iodine intake can cause thyroid function disorders as can be caused by iodine deficiency. There are many people residing in areas with high iodine levels in drinking-water in China. The main aim of the present study was to map the geographical distribution of drinking-water with high iodine level in China and to determine the relationship between high iodine level in drinking-water and goitre prevalence. Iodine in drinking-water was measured in 1978 towns of eleven provinces in China, with a total of 28,857 water samples. We randomly selected children of 8-10 years old, examined the presence of goitre and measured their urinary iodine in 299 towns of nine provinces. Of the 1978 towns studied, 488 had iodine levels between 150 and 300 μg/l in drinking-water, and in 246 towns, the iodine level was >300 μg/l. These towns are mainly distributed along the original Yellow River flood areas, the second largest river in China. Of the 56 751 children examined, goitre prevalence was 6.3 % in the areas with drinking-water iodine levels of 150-300 μg/l and 11.0 % in the areas with drinking-water iodine >300 μg/l. Goitre prevalence increased with water and urinary iodine levels. For children with urinary iodine >1500 μg/l, goitre prevalence was 3.69 times higher than that for those with urinary iodine levels of 100-199 μg/l. The present study suggests that drinking-water with high iodine levels is distributed in eleven provinces of China. Goitre becomes more prevalent with the increase in iodine level in drinking-water. Therefore, it becomes important to prevent goitre through stopping the provision of iodised salt and providing normal drinking-water iodine through pipelines in these areas in China.
This survey examined 59,158 children from 87 schools in 17 out of 24 districts in Sri Lanka for goitre. The overall prevalence rate was 18.8%: 23.2% for girls and 14.0% for boys. Prevalence in districts varied from 30.2% in Kalutara to 6.5% in Matale. It was higher in rural than urban areas, and in inland than coastal areas. The sex ratio of prevalence rates was directly related and the ratio of palpable to visible goitre was inversely related to the severity of the endemic. It is suggested that for a rapid epidemiological assessment when the latter ratio is less than four, it is indicative of endemicity for public health purposes and calls for intervention. The iodination of salt is both practical and feasible in Sri Lanka.
1. Iodine metabolism was studied using labelled sodium iodide in subjects with endemic goitre which is prevalent in the south-west part of Ceylon, where the iodine content of the drinking water was shown to be low. The study was confined mostly to children of school age. 2. The patients showed raised thyroidal uptake of ¹⁸¹ I and 48 h serum protein-bound radio-active iodine, lowered plasma inorganic iodide and urinary iodide. 3. These findings suggest that the goitre which is endemic in Ceylon is due to environmental iodine deficiency rather than to a goitrogen.