Transaminase elevation in patients treated with unfractionated heparin or low molecular weight heparin for venous thromboembolism

The purpose of this study was to evaluate the incidence of transaminase elevation in patients treated with unfractionated (UFH) or low molecular weight heparin (LMWH). Patients receiving UFH, nadroparin, or reviparin for venous thromboembolism and with normal baseline transaminase values were evaluated for serum transaminase levels 10-14 days after the start of heparin therapy or at the end of treatment. The incidence of high transaminase was 4.7% overall (95% CI, 2.2 to 7.3), while it was 2.9% (95% CI, 0.1 to 5.6) and 6.7% (95% CI, 2.5 to 11.0) with UFH and LMWH treated patients, respectively. The difference was equal to -3.8% (95% CI, -8.9 to 1.2) and the common odds ratio was equal to 0.38 (95% CI, 0.12 to 1.16, p =.09). Nadroparin treated patients showed a 5.7% (95% CI, 1.3 to 10.2) incidence of high transaminase levels, while reviparin treated patients presented a 10.3% incidence (95% CI, -0.7 to 21.4). The comparison with UFH showed a mild trend in favor of UFH when compared with nadroparin, but not with reviparin. In conclusion, the incidence of transaminase increase during heparin treatment for a venous thromboembolic event is equal to 3%, 6%, and 10% in UFH-, nadroparin-, and reviparin-treated patients, respectively. LMWHs showed a slightly higher average incidences of hypertransaminasemia as compared with UFH. Differences did not reach statistical significance.