The establishment of regional,gestational age,method-specific thyroid function reference ranges in the evaluation of thyroid function during pregnancy

Objective: The establish trimester-as well as before 9 weeks of pregnancy–and method-specific serum reference interval for thyroid stimulating hormone(TSH),free thyroid hormones(FT4),free three triiodothyronine(FT3) in local area.Method: According to the standards of National Academy of Clinical Biochemistry(NACB),279 women in pre-pregnancy and 2946 in pregnancy period were screened to test serum FT3,FT4 and TSH level variation rate in each trimester above.Results: Both Mean or median value of TSH were drop to a minimum at 8-11 weeks of gestation,established of the bottom,then increased slowly returned the pre-pregnancy level when perinatal period nearby;FT3 and FT4 were also showed a reduction with the gestational age growth.Diagnosis with the reference interval of pre-pregnancy women will lead misjudge about in 4.8% of TSH,15.1% of FT3 and 50% FT4 abnormalities in each pregnancy trimester.Conclusion: Laboratory specific reference interval should be based on different experimental apparatus,methods,and services object at different gestation stages.Further study could be focus on whether the FT4 decline rates as a standard for Immunoassay method and reagent selection during pregnancy.