Reference intervals for thyroid hormones in pregnant Chinese women.
OBJECTIVE
To establish gestation-related reference intervals for thyroid hormones in a Chinese population.


METHODS
A prospective study with 343 healthy pregnant women (5-41 weeks) and 63 non-pregnant controls. Thyroid stimulating hormone (TSH), free thyroxine (T4) and tri-iodothyronine (T3) (and human chorionic gonadotrophin) were measured by immunoassays. The median, 2.5th and 97.5th percentiles at 4-week intervals were calculated. Data were also analysed for significant trends using ANOVA.


RESULTS
Free T3 decreased during pregnancy, whereas free T4 initially increased, peaking between 9-13 weeks and then decreased, the decline becoming significant by week 21. TSH mirrored changes in free T4.


CONCLUSIONS
The gestation-related reference intervals for thyroid hormones should alleviate the misinterpretation of thyroid function in pregnancy.
Panesar
N S
NS
Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR. nspanesar@cuhk.edu.hk
Li
C Y
CY
Rogers
M S
MS
D000328:Adult; D000704:Analysis of Variance; D044466:Asian People; D002681:China; D006063:Chorionic Gonadotropin / Q000097:blood; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods; D008875:Middle Aged; D011247:Pregnancy / Q000097:blood*; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D012016:Reference Values; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood*
D006063:Chorionic Gonadotropin; D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine