Screening for congenital hypothyroidism: The value of retesting after four weeks in neonates with low and very low birth weight

Jagiellonian University, Cracovia, Lesser Poland Voivodeship, Poland
Journal of Medical Screening (Impact Factor: 3.1). 12/2005; 12(4):166-9. DOI: 10.1258/096914105775220697
Source: PubMed


Thyroid-stimulating hormone (TSH), normally a reliable screening test for congenital hypothyroidism (CH), may fail to detect cases among infants who have low and very low birth weight. The purpose of this study was to identify neonates with false-negative screening results.
A province in Poland in which 3,854 neonates had body weight <or=2,500 g, between 1999 and 2001.
TSH levels in blood on filter paper were measured in all neonates between the third and sixth days after birth, but were repeated in low and very low birth weight infants after four weeks of age.
The repeat test showed TSH levels >or= 10 mIU/L in 19 of the 3,854 low birth weight neonates. The final diagnosis in these neonates was permanent CH in two, transient CH in five, possible compensated CH in six and transient high TSH in six. Of the 19, 16 (84%) required iodine and/or thyroxine replacement therapy.
In neonates with low and very low birth weight, normal TSH levels measured between the third and sixth day of life do not exclude thyroid dysfunction, but a repeat TSH measurement after the fourth week of life identifies the false-negative results. In our data, the prevalence of primary and secondary hypothyroidism (both permanent and transient) was about 0.5%.

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Available from: Malgorzata Kumorowicz-Czoch, Nov 20, 2014
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    • "Neonatal thyroid screening is necessary to make an early diagnosis of CHT and prompt thyroid replacement therapy under 1 month of age in the absence of suggestive symptoms. Neonatal thyroid screening in which either TSH or T4 (thyroxin) are measured in heel-stick blood specimens were extended in the mid-1970s to detect thyroid hormones insufficiency as soon as possible.[512] "
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    ABSTRACT: Congenital hypothyroidism (CHT) is one of the most common congenital endocrinal disorders. The prevalence of CHT is estimated about 1 in 3,000 newborns. The prevalence, etiology and associated disorders of abnormal thyroid screening tests are reported in different ranges. In this study, we assessed the pre-term newborns for CHT and associated factors that influence thyroid function. One hundred newborns with the gestational age fewer than 35 weeks were investigated. Baseline serum thyroid stimulating hormone (TSH) and free thyroxin (FT4) levels were measured during the first 5 days of life and were repeated during the first 5 weeks. We analyzed the effects of demographic factors and the presence of respiratory distress syndrome on the alteration of thyroid function tests during the first 5 weeks of life. The mean gestational age (GA) at delivery was 32.35í1.97 (range 28 to 35) weeks. CHT was observed in 13(13%) preterm infants. GA was the only factor which affect the FT4 changes over the two weeks follow-up (P < 0.001, b: -2.783, Power: 70.2%) although the differences between baseline and follow-up amount of TSH were not significantly influenced by GA (P = 0.062, power: 46%). However, the adjusted TSH and FT4 serum level changes during follow-up were significantly different between two groups (between CHT and normal, P = 0.006, 0.000, respectively). It seems that thyroid function tests should be repeated in preterm infants, especially for patients with lower gestational age, to confirm the diagnosis of CHT. Also, CHT should be considered among the newborns that are affected by RDS.
    International journal of preventive medicine 11/2013; 4(11):1271-1276.
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    ABSTRACT: The 1980s have seen widespread growth in the screening of newborn infants for congenital hypothyroidism (CH). By 1982 it was estimated that 7-9 million infants were screened annually.1 There has been further expansion since 1982, not only in communities with highly developed public health programmes, but also in less developed centres.2 Experience from Hong Kong is reported in a previous issue of this journal.3
    Australian paediatric journal 09/1986; 22(3):165-6. DOI:10.1111/j.1440-1754.1986.tb00215.x
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    ABSTRACT: To determine the factors which influence the suppression of thyroid-stimulating hormone (TSH) in infants with congenital hypothyroidism (CH) following treatment. We examined retrospectively the patterns of thyroid function tests from diagnosis to 3 years of age in 140 infants diagnosed with CH from screening. Patients were classified into 3 groups: athyreosis, ectopia and presumed dyshormonogenesis on the basis of thyroid scans. Adequate TSH suppression was defined as plasma TSH concentration <6 mU/l. The factors affecting the suppression of TSH at 6 months and 1 year of age which were evaluated were: initial confirmatory plasma TSH, initial plasma thyroxine (T4), mean age of starting treatment with L-T4, dose of L-T4 at diagnosis, 6 weeks, 3 months and 6 months, and aetiology of the congenital hypothyroidism. Variables were then entered in a stepwise logistic regression model for TSH suppression at 6 months and 1 year of age. All infants had radionuclide scans prior to treatment: athyreosis (n = 39), ectopia (n = 78) and dyshormonogenesis (n = 23). 58% of patients had persistently raised TSH at 6 months of age while 31% of patients had a persistently raised TSH at 1 year of age. There was a significant delay in the normalisation of plasma TSH in athyreosis and ectopia groups compared with dyshormonogenesis. Multiple regression analysis for TSH suppression at 6 months of age found plasma T4 levels and aetiology of CH as independent factors affecting the timing of TSH suppression. Aetiology of CH was the only independent factor affecting TSH suppression at 1 year of age. At 6 months of age, plasma T4 levels at 6 weeks and 3 months, and aetiology of CH were independent factors affecting timing of TSH suppression. However, by 1 year of age, the aetiology of CH was the only independent factor affecting suppression of TSH.
    Hormone Research 02/2004; 62(5):245-51. DOI:10.1159/000081628 · 2.48 Impact Factor
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