Changes in Urinary Iodine Levels Following Bariatric Surgery.

OBJECTIVE: Obesity has become an epidemic in the United States. Although bariatric surgery can effectively achieve weight loss by altering the gastrointestinal tract, it commonly results in micronutrient deficiency, requiring supplementation. Iodine is an essential micronutrient for the synthesis of thyroid hormones. We aimed to investigate changes in urinary iodine concentrations (UIC) in patients following bariatric surgery. METHODS: 85 adults who underwent either laparoscopic sleeve gastrectomy or laparoscopic Roux-en-Y gastric bypass surgery were enrolled. At baseline and 3 months after surgery, we evaluated spot UIC and serum thyroid stimulating hormone (TSH), vitamin D, vitamin B12, ferritin, and folate levels. Participants provided a 24-hour diet recall for iodine-rich foods and information about multivitamin use at each time point. RESULTS: There was a significant increase in median UIC (201 [120.0 - 288.5] vs 334.5 [236.3 - 740.3] µg/L; P < .001), a significant decrease in mean body mass index (44.0 ± 6.2 vs 35.8 ± 5.9; P < .001) and a significant decrease in TSH levels (1.5 [1.2 - 2.0] vs 1.1 [0.7 - 1.6] uIU/mL; P < .001) at 3 months postoperatively compared to baseline. Body mass index, UIC, and TSH levels before and after surgery did not differ based on the type of weight loss surgery. CONCLUSION: In an iodine-sufficient area, bariatric surgery does not cause iodine deficiency nor clinically significant changes in thyroid function. Different surgical procedures with different anatomical alterations in the gastrointestinal tract do not significantly affect iodine status.

THYROID FUNCTION AND METABOLIC SYNDROME: A CROSS-SECTIONAL STUDY IN OBESE AND OVERWEIGHT PATIENTS.

OBJECTIVE: 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. METHODS: This was a cross-sectional observational study of obese and overweight patients seen for initial evaluation at the Boston Medical Center weight-management clinic between February 1, 2013 and February 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. RESULTS: 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 body mass index was 36.06 ± 9.89 kg/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 1.41 µIU/mL, compared with 1.36 µIU/mL in patients without MetS (P = .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. CONCLUSION: Serum TSH level does not appear to be a potentially modifiable risk factor for MetS in obese and overweight individuals.