[Show abstract][Hide abstract] ABSTRACT: Background:
Polybrominated diphenyl ethers (PBDEs) are flame retardant chemicals that were added to many consumer products. Multiple animal studies have shown PBDEs to be thyroid hormone (TH) disruptors. Epidemiologic evidence of PBDE exposure associated with TH disruption has been inconclusive.
We used repeated measures to estimate associations between serum PBDE concentrations and THs in a North American adult cohort.
From 2010-11, we collected ≤ 3 serum samples at approximately 6-month intervals from 52 healthy adult office workers from Boston, Massachusetts for analysis of PBDE congeners and THs.
Geometric mean sum concentrations of the most prevalent PBDE congeners (BDE 28, 47, 99, 100, 153) were 22 ng/g lipid in Winter 2010, 23 ng/g lipid in Summer 2010, and 19 ng/g lipid in Winter 2011. BDE-47 was the predominant congener. Based on a multivariable mixed regression model, we estimated that, on average, a 1-ng/g serum increase in BDE-47 was associated with a 2.6 µg/dL decrease in total T4 (95% CI: -4.7, -0.35). Total T4 was inversely associated with each PBDE congener. Serum concentrations of PBDEs were not strongly associated with total T3, free T4, or TSH.
These results are consistent with those from animal studies showing exposure to PBDEs is associated with a decrease in serum T4. Because the other TH concentrations did not appear to be associated with BDE exposures, our findings do not support effects on the pituitary/thyroid axis. Taken together, our findings suggest that PBDE exposure might decrease the binding of T4 to the serum T4 binding proteins.
Environmental Health Perspectives 09/2015; DOI:10.1289/ehp.1509755 · 7.98 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Metabolic syndrome (MetS) is associated with increased risks of developing cardiovascular disease and type 2 diabetes. Thyroid dysfunction is also a known cardiovascular risk factor. In obese patients, serum thyroid stimulating hormone (TSH) levels tend to be higher than in lean controls. The objective of this study was to assess potential associations between serum TSH levels and MetS as well as individual components of MetS.
This was a cross-sectional observational study of obese and overweight patients seen for initial evaluation at the Boston Medical Center weight management clinic from 2/1/2013-2/1/2014. Demographic, anthropometric, and laboratory data including serum TSH, insulin, glucose, hemoglobin A1C, and lipid levels were obtained from electronic medical records. Associations between serum TSH levels and presence of MetS and its components were assessed.
A total of 3,447 patients, 75.6% female and 38% African-American, without known thyroid dysfunction were included. Mean±SD age was 46.74±15.11 years and mean±SD BMI was 36.06±9.89kg/m(2). Among 1,005 patients without missing data, the prevalence of MetS was 71.84%. In patients with MetS, the median serum TSH was 1.41μIU/mL compared to 1.36μIU/mL in patients without MetS (p=0.45). In multivariate models, there was no significant association between serum TSH levels and the presence of MetS, adjusting for age, sex, race, education, socioeconomic status, and smoking. There were also no significant associations between serum TSH and individual components of the MetS.
Serum TSH level does not appear to be a potentially modifiable risk factor for MetS in obese and overweight individuals.
Endocrine Practice 07/2015; DOI:10.4158/EP15739.OR · 2.81 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Subclinical hypothyroidism during pregnancy has been associated with adverse maternal and fetal outcomes. Pregnant women in the United States have been shown to have mild iodine deficiency. No study has evaluated the thyroid and iodine status of women who are planning to become pregnant in the near future.
Thyroid function tests, thyroid antibodies and urine iodine levels were evaluated in women presenting for preconception screening and counseling. A TSH level above 3.0 mIU/L was considered abnormal.
One hundred and forty-one women enrolled in the study. The median TSH level was 1.70 mIU/L (range 0.43-5.3 mIU/L). Sixteen women (11%) had a TSH above the upper limit of normal (> 3.0 mIU/L). Eleven women (8%) were positive for TPO-Ab and 21 women (15%) for TgAb. Twenty-three women (16%) were positive for at least one thyroid antibody (TPOAb and/or TgAb). Median serum TSH concentrations were higher in women with detectable anti-thyroid antibodies than in women who were antibody negative (2.2 mIU/L: vs. 1.7 mIU/L; p=0.005). The median urinary iodine concentration was 100.5 µg (range 19-843 µg/L).
The present cohort exhibited the lowest median UIC levels to date reported in U.S. women in their child bearing years. One out of every nine women, or eleven percent, had thyroid function tests consistent with subclinical hypothyroidism.
Thyroid: official journal of the American Thyroid Association 07/2015; DOI:10.1089/thy.2015.0063 · 4.49 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background:
Iodinated contrast media (ICM) is a source of excess iodine that may induce thyroid dysfunction. A prospective cohort study was conducted to assess the effects of ICM on urinary iodine clearance and serum thyroid function tests (TFTs) in adults.
In this prospective cohort study of 54 adults undergoing elective computed tomography (CT) scans at an academic medical center, serial urinary iodine concentrations (UIC) and serum TFTs were obtained until UIC normalized following ICM administration. Thyroid volume/nodularity were assessed by ultrasound. Associations between covariates and peak UIC, duration for UIC to peak and normalize, and thyroid dysfunction risk were assessed.
The mean±standard deviation (SD) iodine administered was 34.6±6.0 g. Baseline median (range) UIC was 105.1 (17.0-866.1) μg/L, and serum thyrotropin (TSH) concentration was 1.26 (0.5-11.2) mIU/L. The mean±SD times to achieve peak UIC (median [range]: 3519 [233-157,500] μg/L] and normalized UIC were 1.1±0.5 and 5.2±4.0 weeks, respectively. Four subjects had elevated baseline TSH, and one had missing baseline TSH values. Of the remaining 49 subjects, 11 (22%) developed an abnormal TSH within one to four weeks (six elevated and five decreased). Administered iodine amount correlated with peak UIC following ICM administration (p<0.001). Increasing age and administered iodine amount predicted peak UIC (p=0.024 and p<0.001, respectively). Age, sex, race/ethnicity, smoking status, family history of thyroid disease, personal or family history of thyroid autoimmunity, thyroid volume, presence of thyroid nodules ≥1 cm, iodine dose, baseline UIC, and baseline TFTs were not predictive of durations to achieve peak or normalized UIC.
Peak UIC occurred at 1.1 weeks and normalized by 5.2 weeks following ICM administration for outpatient CT scans. Because thyroid dysfunction developed in 22% of individuals following a single ICM dose, monitoring of thyroid function should be considered in at-risk patients.
Thyroid: official journal of the American Thyroid Association 03/2015; 25(5). DOI:10.1089/thy.2015.0024 · 4.49 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In animals, long-term feeding with peanut (Arachis hypogaea) seed coats causes hypertrophy and hyperplasia of the thyroid gland. However, to date there have been no detailed studies. Here, we explored the thyroidal effects of dietary peanut seed coats (PSC) in rats. The PSC has high levels of pro-goitrogenic substances including phenolic and other cyanogenic constituents. The PSC was mixed with a standard diet and fed to rats for 30 and 60 days, respectively. Animals fed with the PSC-supplemented diet showed a significant increase in urinary excretion of thiocyanate and iodine, thyroid enlargement, and hypertrophy and/or hyperplasia of thyroid follicles. In addition, there was inhibition of thyroid peroxidase (TPO) activity, 5'-deiodinase-I (DIO1) activity, and (Na+-K+)-ATPase activity in the experimental groups of rats as compared to controls. Furthermore, the PSC fed animals exhibited decreased serum circulating total T4 and T3 levels, severe in the group treated for longer duration. These data indicate that PSC could be a novel disruptor of thyroid function, due to synergistic actions of phenolic as well as cyanogenic constituents.
Indian journal of experimental biology 03/2015; 53(3):143-51. · 0.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Objective To examine the relationship between preoperative vitamin D status and post total thyroidectomy hypocalcemia. Methods Retrospective study examining 264 total and completion thyroidectomies between 2007-2011. Subjects included had a recorded 25-hydroxyvitamin D [25(OH)D] level within 21 days prior to or 1 day following surgery, did not have a primary parathyroid gland disorder, and were not taking 1,25-dihydroxyvitamin D3 (calcitriol) prior to surgery. Some subjects were repleted with vitamin D preoperatively if a low 25(OH)D level (typically below 20 ng/mL) was identified. Preoperative 25(OH)D, concurrent neck dissection, integrity of parathyroid glands, final pathology, postoperative PTH, calcium nadir and repletion, and length of stay were examined. Results The mean preoperative 25(OH)D for all subjects was 25 ng/mL and the overall rate of postoperative hypocalcemia was 37.5%. Lower preoperative 25(OH)D did not predict postoperative hypocalcemia (p=0.96), however, it did predict the need for postoperative 1,25-dihydroxyvitamin D3 administration (p=0.01). Lower postoperative PTH levels (p=0.001) were associated with postoperative hypocalcemia. Conclusion Preoperative 25(OH)D did not predict a postoperative decrease in serum calcium although it did predict the need for 1,25-dihydroxyvitamin D3 therapy in hypocalcemic subjects. We recommend that 25(OH)D be assessed and, if indicated, repleted preoperatively in patients undergoing total thyroidectomy.
Endocrine Practice 12/2014; 1(-1):1-21. DOI:10.4158/EP14264.OR · 2.81 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Context:
Thyroid hormone production is dependent on adequate iodine intake. Excess iodine is generally well-tolerated, but thyroid dysfunction can occur in susceptible individuals after excess iodine exposure. Radiological iodinated contrast media represent an increasingly common source of excess iodine.
This review will discuss the thyroidal response after acute exposure to excess iodine; contrast iodine-induced thyroid dysfunction; risks of iodine-induced thyroid dysfunction in vulnerable populations, such as the fetus, neonate, and patients with impaired renal function; and recommendations for the assessment and treatment of contrast iodine-induced thyroid dysfunction.
Data for this review were identified by searching PubMed, Google Scholar, and references from relevant articles from 1948 to 2014.
With the increase in the use of computed tomography scans in the United States, there is increasing risk of contrast-induced thyroid dysfunction. Patients at risk of developing iodine-induced thyroid dysfunction should be closely monitored after receiving iodinated contrast media and should be treated as needed.
[Show abstract][Hide abstract] ABSTRACT: Purpose of review:
This review will present a general overview of the sources, human studies, and proposed regulatory action regarding environmental perchlorate exposure.
Some recent studies have reported significant associations between urinary perchlorate concentrations, thyroid dysfunction, and decreased infant intelligence quotient in groups who would be particularly susceptible to perchlorate effects. An update regarding the recently proposed regulatory actions and potential costs surrounding amelioration of perchlorate contamination is provided.
The potential adverse thyroidal effects of environmental perchlorate exposure remain controversial, and further research is needed to further define its relationship to human health among pregnant and lactating women and their infants.
Current Opinion in Endocrinology Diabetes and Obesity 08/2014; 21(5). DOI:10.1097/MED.0000000000000090 · 3.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Objective: Thyroid dysfunction is associated with impaired cognitive development. Perchlorate decreases thyroidal iodine uptake, potentially reducing thyroid hormone production. It is unclear whether perchlorate exposure in early life affects neurodevelopment. Design: Historical cohort analysis. Patients: During 2002-2006, 21,846 women at gestational age <16 weeks recruited from antenatal clinics in Cardiff, UK and Turin, Italy were enrolled in the Controlled Antenatal Thyroid Screening Study (CATS). We undertook a retrospective analysis of 487 mother-child pairs in mothers who were hypothyroid/hypothyroxinemic during pregnancy and analyzed whether first trimester maternal perchlorate levels in the highest 10% of the study population were associated with increased odds of offspring IQ being in the lowest 10% at age 3 years. Main Outcome Measures: Maternal urinary perchlorate, offspring IQ. Results: Urine perchlorate was detectable in all women (median 2.58μg/liter); iodine levels were low (median 72μg/liter). Maternal perchlorate levels in the highest 10% of the population increased the odds of offspring IQ being in the lowest 10% OR=3.14 (95%CI 1.38, 7.13) p=0.006 with a greater negative impact observed on verbal OR=3.14 (95%CI 1.42, 6.90) p=0.005 than performance IQ. Maternal levothyroxine therapy did not reduce the negative impact of perchlorate on offspring IQ. Conclusions: This is the first study using individual-level patient data to study maternal perchlorate exposure and offspring neurodevelopment and suggests that high-end maternal perchlorate levels in hypothyroid/hypothyroxinemic pregnant women have an adverse effect on offspring cognitive development, not affected by maternal levothyroxine therapy. These results require replication in additional studies, including in the euthyroid population.
[Show abstract][Hide abstract] ABSTRACT: Current treatments for cystoid macular edema (CME) in retinitis pigmentosa (RP) are not always effective, may lead to adverse effects, and may not restore visual acuity. The present research lays the rationale for evaluating whether an iodine supplement could reduce CME in RP.
[Show abstract][Hide abstract] ABSTRACT: Objective: Surprisingly few studies have examined weight change in hypothyroid patients after initiation of levothyroxine (LT4) therapy. Our study aimed to investigate weight change after initiation of treatment for primary hypothyroidism.Methods: Using electronic medical records from Boston Medical Center, Boston, MA, we performed a retrospective cohort study from 1/1/2003-2/1/2011. Adults aged ≥ 18 years with newly-diagnosed primary hypothyroidism with initial thyroid-stimulating hormone (TSH) ≥10mIU/L were identified. Patients with post-surgical hypothyroidism, thyroid cancer, and history of radioactive iodine or head/neck radiation, congestive heart failure, anorexia nervosa, end-stage renal disease, cirrhosis, pregnancy, or prescription weight loss medication use were excluded. TSH and weight at diagnosis and up to 24 months after LT4 initiation were collected. Weight change was assessed at the first post-treatment serum TSH <5mIU/L.Results: A total of 101 patients (mean age 48±15 yrs, 71% women) were included. Initial median (range) TSH was 18.3mIU/L (10.1-710.5) and weight was 79.6kg (41.5-167.5). Post-treatment median (range) TSH was 2.3mIU/L (0.04-5) and weight change at a median of 5 months (1.1-25.6) was -0.1kg (-20.6-7.7). Initial median (range) BMI of 95 patients was 29.3 (19.5-56.1) and the median change in BMI was - 0.1kg/m2 (-7.1-3.3). Only 52% of patients lost weight, with a mean weight loss 3.8±4.4 kg. Gender, race, education, insurance type, age, initial TSH, time to normalization of TSH, and initial weight were not associated with changes in weight or BMI.Conclusion: Contrary to popular belief, there was no significant weight change after initiating LT4 treatment in 101 patients with primary hypothyroidism.
Endocrine Practice 06/2014; 1(-1):1-19. DOI:10.4158/EP14072.OR · 2.81 Impact Factor