Elevation of hepatic transaminases after enoxaparin use: Case report and review of unfractionated and low-molecular-weight heparin-induced hepatotoxicity

Enoxaparin, a low-molecular-weight heparin (LMWH), is widely used for the t reatment and prophylaxis of thromboembolic disorders, such as deep vein thr ombosis. Low-molecular-weight heparin products have smaller and more unifor m molecular weights than unfractionated heparin, allowing them to exhibit a much greater affinity for factor Xa than factor IIa. Compared with traditi onal unfractionated heparin, LMWHs have proved to be equally efficacious an d may be safer. The distinctive characteristics of LMWHs have resulted in d ecreased rates of bleeding and equivalent rates of thrombocytopenia compare d with unfractionated heparin. This favorable safety profile has been ident ified in several studies and may have led clinicians to believe that LMWHs have lower frequencies of all common side effects. A 66-year-old woman deve loped increased hepatic transaminases during treatment with enoxaparin for a deep vein thrombosis; they returned to normal after enoxaparin discontinu ation. A causal relationship between unfractionated heparin and asymptomati c, transient increases in hepatic transaminase levels has been documented; these increased levels also appear to be an underrecognized, adverse effect of LMWH therapy.