Reference data of thyroid hormones for pregnancy and lactating women in Zhejiang

Objective To set up the reference ranges of thyroid hormones for pregnant and lactating woman in Zhejiang. Methods A total of 338 pregnancy, 322 lactating women and 139 non-pregnant women (as a control) were selected from 1 079 women in 13 survey sites of Zhejiang as survey subjects, through the questionnaire survey and thyroid B-ultrasound tests from June 2010 to September 2010. The level of urinary iodine was measured by spectrophotometer, and the thyroid hormone [free triiodothyronine (FT3), free (unbound) thyroxin (FT4), triiodothyronine (T3), tetraiodothyronine (T4), thyroid stimulating hormone (TSH)] was measured by automated chemiluminescence immunoassay. Analysis of thyroid hormone 95% in pregnant women and lactating women. Results The median urinary iodine of all women investigated were in optimal urine levels (150-249 μg/L), which indicated they were in iodine sufficient status. The FT3 index of lactating women was higher than that of pregnant women and non pregnant women (Zlactating-pregnant= 3.98, Zlactating-non pregnant= 2.46, all P < 0.05); the FT4 index level of lactating women was higher than that of pregnant women and non pregnant women (Zlactating-pregnant= 2.68, Zlactating-non pregnant= 2.25, all P < 0.05); the T3 index level of lactating women was higher than that of pregnant women and non pregnant women (Zlactating-pregnant= 3.51, Zlactating-non pregnant= 2.41, all P < 0.05); levels of T4 in lactating women was the highest (Zlactating-non pregnant= 2.30, Zlactating-pregnant= 4.90, Zpregnant-non pregnant= 1.57, all P < 0.05); TSH index of lactating women and non pregnant women were higher than that of pregnant women (Zlactating-pregnant= 2.81, Zpregnant-non pregnant= 1.68, all P < 0.05). And in pregnant, the 95% medical reference interval of FT3 was 3.37-6.53 pmol/L, FT4 was 10.68-20.85 pmol/L, T3 was 1.40-2.79 nmol/L, T4 was 72.72-166.41 nmol/L, and TSH was 0.15-4.44 mU/L; in lactating woman, FT3 was 3.39-6.44 pmol/L, FT4 was 10.81-20.33 pmol/L, T3 was 1.44-2.77 nmol/L, T4 was 71.94-164.61 nmol/L, and TSH was 0.25-4.47 mU/L. Conclusion The thyroid hormone levels of pregnant and lactating women are different from those of non-pregnant women, therefore establishing reference data of thyroid hormones for pregnant and lactating women may be a very important step for clinical practice. Key words: Pregnant women; Lactating women; Thyroid hormones; Reference values