[Status of lactating women's iodine nutrition and thyroid function in different iodine nutrition level of children in Gansu Province].

OBJECTIVE: To assess the iodine nutrition and thyroid function of lactatingwomen in different iodine nutrition level of children in Gansu Province, and provide a scientific basis for iodine supplementation.

METHODS: Liangzhou district( the median urinary iodine was greater than or equal to 300 g/L), Linze county( the median urinary iodine was from 200 to 299 g/L) and Huating county( the median urinary iodine was from100 to 199 g/L) were selected according to 8-10 years old children urinary iodine in2009. Huating county, Liangzhou district and Linze county were as iodine excessive area, iodine suitable area 1 and iodine suitable area 2, respectively in 2014. One township was randomly selected from the east, west, south, north and middle parts of each research point, 10 lactating women were randomly collected in each township, who was tested urine samples and thyroid function. Salt intake was surveyed in 3 townships. 2 samples were collected in centralized water supplies, 1 sample was collected in its coverage by the east, west, south, north and middle parts; 1 sample was collected by the east, west, south, north and middle parts in decentralized water supplies, which were tested of water iodine.

RESULTS: The medians of water iodine were 2. 32, 0. 70 and 6. 18 μg/L and the medians of salt iodine were 25. 3, 25. 0 and 28. 6 mg/kg for iodine excessive area, iodine suitable area 1 and iodine suitable area 2, respectively. Per capita daily intake of salt were 15. 0, 11. 3 and 4. 7 g for iodine excessive area, iodine suitable area 1 and iodine suitable area 2 respectively, there were statisticant differences. The median urinary iodine of lactating women were 181. 8, 143. 1 and 104. 9 μg/L for iodine excessive area, iodine suitable area 1 and iodine suitable area 2, respectively. The medians of thyroidstimulating hormone( TSH) were 2. 3, 2. 2 and 1. 9 mIU/L, mean values of free thyroxine( FT4) were 15. 0, 13. 9 and 14. 6 pmol/L, mean values of free triidothyronine( FT3) were 5. 0, 4. 8 and 4. 6 pmol/L for iodine excessive area, iodine suitable area 1 and iodine suitable area 2 respectively, there were not statistically differences. The positive rate of thyromicrosomal antibody( Tm Ab) were 3. 6 %, 11. 3 % and 13. 2 % and the positive rate of thyroglobulin antibody( Tg Ab) were 3. 6 %, 11. 3 % and 11. 3 % for iodine excessive area, iodine suitable area 1 and iodine suitable area 2 respectively( P >0. 05). Prevalence of thyroid function disorders were 14. 3 %, 21. 0 % and 9. 4 % and prevalence of low-FT4 syndrome were 7. 1 %, 4. 8 % and 1. 9 %, prevalence of subclinical hypothyroidism were 3. 6 %, 11. 3 % and 3. 8 % for iodine excessive area, iodine suitable area 1 and iodine suitable area 2 respectively( P > 0. 05).

CONCLUSION: Iodine nutrition level was appropriate for lactating women in 3 areas, but some lactating women were iodine deficiency or iodine excess. There were occurred thyroid function disorders in some lactating women in 3 areas. The lactating women's iodine nutrition and thyroid function should be monitored and the normal reference value of thyroid function on lactating women should be established also.