Trimester-specific reference intervals of TAT, TM, tPAI-C and PIC for healthy Chinese pregnant women

Aim: Pregnancy is a hypercoagulability state, the aim of this study was to observe the changes of thrombin-antithrombin complex (TAT), thrombomodulin (TM), tissue plasminogen activator-inhibitor complex (tPAI-C) and plasmin-α2-antiplasmin complex (PIC) during pregnancy and establish trimester-specific reference intervals for Chinese healthy pregnant women.

Methods: In total 190 Chinese healthy pregnant women (first trimester 59 cases, second trimester 60 cases and third trimester 71 cases) were recruited in North China. TAT, TM, tPAI-C and PIC were processed on Sysmex HISCL 5000 automated chemiluminescence immune detection system. Trimester-specific reference intervals were established with the 2.5th and 97.5th percentile of the distribution.

Results: The reference intervals for TAT, TM, tPAI-C, PIC at trimester 1 were 0.40-3.65 ng/mL, 4.85-8.80 TU/mL, 1.75-6.40 ng/mL, 0.25-1.05 μg/mL, respectively. At trimester 2, the reference intervals were 1.65-8.61 ng/mL, 5.70-9.93 TU/mL, 2.91-7.71 ng/mL, 0.33-2.02 μg/mL, respectively. At trimester 3, the reference intervals were 3.16-12.68 ng/mL, 5.50-14.24 TU/mL, 2.70-10.69 ng/mL, 0.24-1.54 μg/mL, respectively.

Conclusions: The changes of TAT, TM, tPAI-C, PIC during pregnancy are presented, and trimester-specific reference intervals for healthy pregnant women are described. The levels of TAT, TM, tPAI-C were increased gradually from trimester 1 to trimester 3, while the PIC level remains stable during all trimesters.