Endocrine Abstracts

Introduction: Adequate iodine intake is important in pregnant women.

Objective: To determinate iodine status and thyroid volumen (TV) in healthy pregnant women from Navarra (Spain), and to evaluate possible influence of diet.

Methods: A cross-sectional study of 144 women in the first trimester of pregnancy (single pregnancies) was carried during 2014. We measured thyroid-stimulating hormone (TSH), free thyroxine (fT4) and antithyroid antibodies in serum at 9 week of gestational age, and urinary iodine (UI) in a spot-urine sample. A thyroid ultrasonography was performed, and a questionnaire to estimate iodine intakes from diet, iodized salt and supplements was cumplimented at 10 week of gestational age.

Results: Studied women were 90.3% caucasic, mean age was 33.6±4.1 years old and mean BMI 24.3±4.4. A total of 100 subjects (69.4%) consumed iodized salt, 75 of them before pregnancy. All women were taking iodinated supplements (200 μg/day), 40% pregestational. Serum TSH was 1.57±1 mIU/l and fT4 1.04±0.1 ng/dl. Thyroid antibodies were positive in 23 women (16%). Median UI at 10 gestational week was 242 μg/l, considered adequate by WHO criteria. 31.9% of women (n=46) had UI <150 μg/l, and only 4.9% <50 μg/l. Mean TV was 8.1±2.5 ml. Serum TSH, fT4 and thyroid autoinmunity were similar in iodine-sufficient and iodine-insufficient women (UI ≥150 and <150 μg/l respectively). TV in iodine-insufficient women was greater than in iodine-sufficient group (8.9±2.6 vs 7.7±2.4 ml; P=0.008). There were no differences in age, BMI, smoking status, use of iodized salt, pregestational use of iodine supplements or estimates of iodine intake from diet between UI<150 and UI ≥150 μg/l women.

Conclusions: Pregnant women of our population are iodine sufficient, probably due to sistematic use of iodine supplements and high consume of iodized salt. Thyroid volume was larger in iodine-insufficient women. We failed to identify other diet factors associated with iodine status.