Effects of different water iodine level on iodine nutrition and thyroid function in pregnant women.

Objective To understand the effects of different water iodine level on iodine nutrition and thyroid function in pregnant women, and provide a reference for prevention and treatment of iodine deficiency disorders in the future. Methods According to the background material of water iodine in provinces given non- iodized salt, the administrative villages with water iodine content < 10, 10 - 49, 50 - 99, 100 - 299 and ≥300 μg/L were selected as survey sites in Shandong, Shanxi, Hebei, Henan, Jiangsu and Anhui provinces. Urine, blood, drinking water and salt samples were collected from pregnant women at the site of investigation, and urinary iodine, serum iodine, thyroid function and antibody index, water iodine, and salt iodine were measured; thyroid volume was also examined. Results A total of 575 pregnant women were investigated. The medians urinary iodine of pregnant women with water iodine 0.05). And with the increase of water iodine levels, the abnormal rate of TSH showed the phenomenon of middle low and both ends high (U type, χ2 = 16.729, P 0.05). And there was a statistically significant difference in the detection rate of subclinical hypothyroidism (χ2 = 11.869, P < 0.05). The rates of goiter in pregnant women among different water iodine groups were less than 5%. The difference in detection rates of thyroid nodules was statistically significant (χ2 = 13.591, P < 0.05), and the rate was the highest in water iodine ≥300 μg/L group (21.33%, 16/75). Conclusions In water iodine ≥300 μg/L group, urinary iodine level of pregnant women is in the level of iodine excess, and serum iodine level, FT4 level, thyroid nodules detection rate are higher. The abnormal rate of serum TSH and the detection rate of hypothyroidism show a U curve that increases at iodine deficiency and iodine excess. Key words: Water; Iodine; Pregnant women; Thyroid