Abstract:

Objective To investigate the normal reference interval of specific thyroid⁃stimulating hormone （TSH）in women during pregnancy in Sichuan province of China. Methods TSH test results were collected in pregnant women in obstetrics or gynecology outpatient clinic of the Second West China Hospital of Sichuan University between January 1，2015，and December 30，2020. Reference intervals were established according to whether the thyroid peroxidase antibodies（TPOAb）was positive or not and all procedures were conducted based on the docu⁃ ment CLSI EP28⁃A3 by the Clinical Laboratory Standards Institute. Results A total of 14，332 pregnant women in the TPOAb⁃negative group and 10，254 pregnant women in the TPOAb⁃positive group who met the criteria were included. The median TSH levels were lowest in early pregnancy，highest in late pregnancy，and in between in mid⁃ pregnancy in both groups，with consistent trends. According to the CLSI EP28⁃A3 document，we established the reference intervals of TSH in early，mid and late pregnancy for the TPOAb⁃negative group were 0.02 ~ 5.23 mIU/L， 0.03 ~ 5.24 mIU/L and 0.37 ~ 5.68 mIU/L，respectively；for the TPOAb⁃positive group were 0.23 ~ 4.73 mIU/L， 0.35 ~ 4.67 mIU/L，0.43 ~ 4.75 mIU/L，respectively. Conclusions It is essential to establish specific reference intervals for serum TSH during pregnancy，and thyroid hormone changes should be monitored throughout pregnancy in TPOAb⁃positive women.

Key words:

pregnancy, reference interval, thyroid stimulating hormone（TSH）, thyroid peroxidase antibody（TPOAb）