Iodine Deficiency in Pregnant Women in the Apparently Iodine-sufficient Capital City of Turkey

Objective: Previous studies of the current iodine status in Turkey have yielded contradictory results. Although urinary iodine concentration (UIC) in school age children (SAC) suggests sufficient iodine status, studies on neonatal thyroid-stimulating hormone (TSH) indicate that iodine deficiency is a continuing problem. We aimed to assess the iodine nutritional status of pregnant women living in Ankara, an area that has appeared to be iodine sufficient in earlier studies.

Design: Hospital-based, noninterventional, prospective, cross-sectional study.

Methods: A total of 162 pregnant women in their second trimester were examined regarding iodized salt use, UIC, presence or absence of goitre and thyroid function. Goitre status was determined by palpation. UIC was measured using colorimetric method based on Sandell-Kolthoff reaction. Thyroid hormones and TSH were measured by chemiluminescence immunoassays.

Results: While the proportion of iodized salt use was 80·2%, UIC was below 150 μg/l in 72·8% of the women. The median UIC was 80·5 (8·9-340·3) μg/l, indicating insufficient iodine intake. Total goitre rate was 15·4%. Preferential T3 secretion reflected by elevated molar ratios of FT3/FT4 was present in 89·5% of the women. 12·4% had subclinical hypothyroidism or isolated hypothyroxinaemia based on serum TSH and FT4 levels.

Conclusions: Our study shows that iodine deficiency is a serious problem among pregnant women in Ankara. These data confirm that iodine nutritional status among SAC does not reflect the iodine supply for pregnant women. We propose that nationwide surveillance studies should urgently be performed to directly assess and monitor the iodine status of pregnant women. We also consider that pregnant women in Turkey should be supplemented by iodine-containing preparations in addition to iodized salt.