[Study on the iodine status of pregnant women and thyroid function of neonate in high iodine area].

Objective: To reveal the iodine status of pregnant women and its impact on thyroid function of neonates in high iodine area.

Methods: A total of 210 pregnant women were chosen from a hospital in Haixing county, Hebei province. Pregnant women's random urinary and neonates' cord blood were collected. The urinary iodine concentration (UIC) was examined by arsenic-cerium catalytic spectrophotometry. The levels of free triiodothyronine (FT3), free thyroxine (FT4) and sensitive thyroid-stimulating hormone (sTSH) in serum were measured by chemiluminescence.

Results: The age of 210 pregnant women was (27.69 +/- 4.73) years old, whose urinary iodine median (inter-quartile range ) was 1240.70 (1292.68) microg/L. 84.3% (177/210) of the pregnant women had excessive iodine intake (UIC > or = 500 microg/L), 13.8% (29/210) had more than adequate iodine intake( UIC within 250 - 499 microg/L), 0.5% (1/210) had adequate iodine intake (UIC within 150 - 249 microg/L) and 1.4% (3/210) had insufficient iodine intake (UIC < 150 microg/L). The average serum level of FT3, FT4 in neonates were (2.93 +/- 0.59), (15.03 +/- 1.92) pmol/L, respectively. The median (inter-quartile range) of serum sTSH in neonates were 7.33 (5.59) mU/L 78.1% (164/210) of the neonates' serum TSH were beyond 5 mU/L. There were no correlation between pregnant women's urinary iodine level and neonates' serum FT3 and sTSH level (P > 0.05), but there was a positive correlation between pregnant women's urinary iodine level and neonates' serum FT4 level (P < 0.01). Serum FT4 level of the neonates with whose mothers had insufficient iodine intake ((12.99 +/- 1.10) pmol/L) were statistically lower than those with their mothers had excessive iodine intake (15.16 +/- 1.83) pmol/L) (P < 0.05).

Conclusion: Most of the pregnant women in high iodine area were excessive for iodine nutrition, but still a few pregnant women had insufficient iodine nutrition. The level of neonates' serum sTSH were relatively high and monitoring of risk of hypothyroidism and subclinical hypothyroidism should be strengthened.