title: Trimester- and Assay-Specific Thyroid Reference Intervals for Pregnant Women in China.
abstract: Objective. The guidelines of the American Thyroid Association (ATA) recommend an upper limit reference interval (RI) of thyroid stimulating hormone (TSH) of 2.5 mIU/L in the first trimester of pregnancy and 3.0 mIU/L in subsequent trimesters, but some reported ranges in China are significantly higher. Our study aimed to establish trimester- and assay-specific RIs for thyroid hormones in normal pregnant Chinese women. Methods. In this cross-sectional study, 2540 women with normal pregnancies (first trimester, n = 398; second trimester, n = 797; third trimester, n = 1345) and 237 healthy nonpregnant control subjects were recruited. Serum TSH, free thyroxin (FT4), thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TgAb) levels were determined by automated chemiluminescence with an Immulite 2000 system (Siemens, Erlangen, Germany). After outliers were excluded, the 2.5-97.5th percentiles were used to define the RIs. Results. The RIs of thyroid function in the first, second, and third trimesters of pregnancy and in nonpregnant controls were 0.07-3.96, 0.27-4.53, 0.48-5.40, and 0.69-5.78 mIU/L for TSH and 9.16-18.12, 8.67-16.21, 7.80-13.90, and 8.24-16.61 pmol/L for FT4, respectively. Conclusion. The trimester- and assay-specific RIs of thyroid function during pregnancy differed between trimesters, which suggests that it is advisable to detect and avoid misclassification of thyroid dysfunction during pregnancy for women in Henan, China.
authors.affiliation: Clinical Laboratory Department, The Third Affiliated Hospital of Zhengzhou University, No. 7 Front Kangfu Street, Er'qi Distric, Zhengzhou 450052, China.
authors.forename: Jinfang
authors.initials: J
authors.lastname: Xing
authors.affiliation: Clinical Laboratory Department, The Third Affiliated Hospital of Zhengzhou University, No. 7 Front Kangfu Street, Er'qi Distric, Zhengzhou 450052, China.
authors.forename: Enwu
authors.initials: E
authors.lastname: Yuan
authors.affiliation: Clinical Laboratory Department, The Third Affiliated Hospital of Zhengzhou University, No. 7 Front Kangfu Street, Er'qi Distric, Zhengzhou 450052, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.affiliation: Clinical Laboratory Department, The Third Affiliated Hospital of Zhengzhou University, No. 7 Front Kangfu Street, Er'qi Distric, Zhengzhou 450052, China.
authors.forename: Yuchao
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Clinical Laboratory Department, The Third Affiliated Hospital of Zhengzhou University, No. 7 Front Kangfu Street, Er'qi Distric, Zhengzhou 450052, China.
authors.forename: Xiangying
authors.initials: X
authors.lastname: Meng
authors.affiliation: Clinical Laboratory Department, The Third Affiliated Hospital of Zhengzhou University, No. 7 Front Kangfu Street, Er'qi Distric, Zhengzhou 450052, China.
authors.forename: Xia
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Clinical Laboratory Department, The Third Affiliated Hospital of Zhengzhou University, No. 7 Front Kangfu Street, Er'qi Distric, Zhengzhou 450052, China.
authors.forename: Shouhua
authors.initials: S
authors.lastname: Rong
authors.affiliation: Clinical Laboratory Department, The Third Affiliated Hospital of Zhengzhou University, No. 7 Front Kangfu Street, Er'qi Distric, Zhengzhou 450052, China.
authors.forename: Zhongxing
authors.initials: Z
authors.lastname: Lv
authors.affiliation: Clinical Laboratory Department, The Third Affiliated Hospital of Zhengzhou University, No. 7 Front Kangfu Street, Er'qi Distric, Zhengzhou 450052, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Tian
authors.affiliation: Clinical Laboratory Department, The Third Affiliated Hospital of Zhengzhou University, No. 7 Front Kangfu Street, Er'qi Distric, Zhengzhou 450052, China.
authors.forename: Liting
authors.initials: L
authors.lastname: Jia