HEPTEST: a suitable method for monitoring heparin during pregnancy

Abstract

Methods of monitoring heparin in pregnancy are problematic. The aim of this study was to assess the plasma HEPTEST as a rapid and reliable test for heparin monitoring in pregnancy. HEPTEST, activated partial thromboplastin time (APTT) and chromogenic anti-Xa assays were performed on individual heparin-spiked plasma samples from two groups: normal non-pregnant women (n = 6) and normal pregnant women during the third trimester (n = 6). Heparin activity curves were established in plasma from both groups for low (< 0.3 IU/ml), intermediate (0.3-0.7 IU/ml) and high (> 0.7 IU/ml) heparin concentrations and validated by comparison with the anti-Xa chromogenic assay. Both the APTT and HEPTEST demonstrated good correlation with anti-Xa levels across all heparin concentrations in both plasma groups (r range = 0.879-0.945). In comparison with the APTT, the HEPTEST showed better correlation with anti-Xa levels at low concentrations of heparin (r values 0.933 vs. 0.772, respectively). For both the APTT and HEPTEST there were significant differences between the clotting times in pregnant and non-pregnant plasma at a number of heparin concentrations. This data supports the plasma HEPTEST as an acceptable alternative to the chromogenic anti-Xa assay for monitoring heparin thromboprophylaxis in pregnancy.

Heptest-STAT, a new assay for monitoring of low-molecular-weight heparins, is not influenced by pregnancy-related changes of blood plasma

“…Pregnancy results in increased levels of various coagulation factors and heparin-binding proteins (19). Campbell et al have shown that in the original Heptest clotting assay, clotting times became progressively shorter for plasma from pregnant women compared with plasma from non-pregnant women (8). The authors suggested that plasma from pregnant women should be used when constructing calibration curves if the assay was to be used for heparin monitoring in pregnancy.…”

“…Plasma volume is expanded, renal clearance increases, and volume of distribution of anticoagulants changes (2). Therefore, anti-factor Xa activity monitoring may be helpful to optimise the treatment (8,9).…”

“…For use of the assay during pregnancy, it has been suggested that the assay needed to be calibrated using heparin dilutions in plasma from pregnant women (8), and that individual reference curves are needed for each LMWH.…”

Comparison of the anticoagulant response of a novel fluorogenic anti-FXa assay with two commercial anti-FXa chromogenic assays

“…For example, many studies have compared the responses of different anti-FXa chromogenic-based assays [16,17,29,30]. In one such study, anti-FXa levels were compared using three different commercial chromogenic kits [17].…”

Monitoring of Hemostasis and Management of Anticoagulant Thromboprophylaxis in Pregnant Women with Increased Risk of Fetal Loss

“…43 Plasma Heptest is an appropriate alternative to the chromogenic anti-Xa test for the assessment of thromboprophylaxis during pregnancy. 44 For monitoring LMWH effectiveness, anti-Xa level is commonly used as a "peak" test. The samples are collected 3 to 4 hours after LMWH administration, when the amount of LMWH in the plasma is expected to be highest.…”