[Epidemiological investigation on thyroid disease among fertile women in different iodine intake areas of Shanxi province].

OBJECTIVE: To understand the prevalence of thyroid diseases and its influencing factors of iodine on thyroid gland function and autoimmune among fertile women in different iodine intake areas.

METHODS: Cross-sectional method was used for descriptive epidemiology. 236 women aged 19 to 45 years were sampled in 2011, in Shanxi province. Questionnaire was used to include general data on place, name, age etc. Sample of water from home, one time random urine sample and venous blood were collected to test the iodine contents using arsenic and cerium catalysis spectrophotometric methods. Finally, in blood, free triiodothyronine (FT3), free thyroxine (FT4), thyrotrophin (TSH) in blood were tested under auto-CLIA and anti-thyroid peroxidase (anti-TPO), anti-thyroglobulin (anti-TG) through radio-immunological methods.

RESULTS: 1)The urine iodine's medians were 486.9 µg/L for fertile women in high iodine areas, and 192.6 µg/L in low iodine areas, with difference on urine iodine level statistically significant (Z = -10.676, P = 0.000). 2) Levels of blood FT3 and FT4 in women from high iodine areas were obviously lower than those from proper iodine areas(t = -2.884, P = 0.004; t = -2.862, P = 0.005), but the level of TSH in high iodine areas was higher than that of proper iodine areas(t = 2.332, P = 0.021). 3) In both areas, the rate of the thyroid dysfunction with positive antibodies was obviously higher than those with negative antibodies (χ² = 20.941, P = 0.000;χ² = 5.596, P = 0.018), while the rate of the thyroid dysfunction with positive antibodies and the level of TSH in the blood for high iodine women higher than those in women with proper iodine level(χ² = 5.708, P = 0.37;t = -2.177, P = 0.031). 4)The morbidity rate of inferior clinical hyperthyroidism for women in high iodine areas was obviously higher than those in proper iodine areas(χ² = 9.542, P = 0.003), while the morbidity rate of inferior clinical hypothyroidism for women with positive antibodies in two areas obviously higher than those with negative antibodies (χ² = 17.264, P = 0.000; χ² = 6.002, P = 0.044).

CONCLUSION: Morbidity rate of inferior clinical hypothyroidism for women in high iodine areas was obviously higher than those in proper iodine areas, suggesting that there were potential risks of hypothyroidism for overdose iodine intake which causing the existence of positive thyroid antibodies. Monitoring programs on iodine nutrition and thyroid function among women living in high iodine areas should be strengthened.