Iodine status and thyroid function of 330 pregnant women from Nice area assessed during the second part of pregnancy

Iodine deficiency (ID) is still common in Western Europe and its prevention remains a challenge, particularly during pregnancy. We studied 330 pregnant women in the third trimester of pregnancy for ioduria (UIE) and thyroid tests (TSH, fT4). We collected information on personal history of thyroid disease and treatment with thyroid hormones or iodinated pregnancy tablets. Median UIE was 64 microg/l, reflecting inadequate iodine intake in our population. According to the UIE threshold used for diagnosis (100 to 150 microg/l), ID was present in 74.3% to 85.8% of women; 5.4% had excessive iodine intake, including one taking iodine fortified tablets. Only 8.8% had adequate intake, suggesting that current strategies to eradicate ID are inefficient in our country. Among the 22 women taking iodine supplements, only three had adequate UIE and four had UIE below the detection level, which could suggest either poor compliance or insufficient supplementation. Median fT4 was 12.3pmol/l (8-20.1) and TSH 1.93mUI/l (0.24-6.57). We used different thresholds proposed in the literature to diagnose: hypothyroxinemia: 41.2% were less than 12pmol/l, 10% less than 10.3pmol/l and 1.8% less than 9pmol/l (lower limit of our reference range); subclinical hypothyroidism: 26.3% had TSH greater than 2.5 or 3.9% greater than 4mUI/L, 1.2 to 13% had combined low fT4 (