[Thrombocytopenia induced by low molecular weight heparin]

Two cases of thrombocytopenia due to a low molecular weight heparin (Fraxiparine) are reported. The first case was a 35-year-old alcoholic man with acute mild pancreatitis. After having been treated with Fraxiparine for 12 days to prevent venous thrombosis, routine laboratory studies revealed a thrombocytopenia (49 G.l-1). At the same time, a minor haemorrhage occurred in the nasogastric tube. Prothrombin time, partial thromboplastin time, fibrin degradation products and D-dimers remained normal. There were no soluble fibrin monomers. Fraxiparine was discontinued. The thrombocyte count continued to decrease (12 G.l-1) up to the thirteenth day, it raised 3 days later to 110 G.l-1, and returned to normal after 9 days more (395 G.l-1). The second patient was a 58-year-old man given prophylactic Fraxiparine between the 5th and 16th days after admission for a severe asthma attack. Here again, after 12 days of treatment, the thrombocyte count decreased to 74 G.l-1. There were no other abnormalities, neither clinically nor in laboratory findings. Heparin administration was discontinued and the thrombocytopenia had resolved 3 days later. In both patients, the diagnosis of thrombocytopenia elicited by low molecular weight heparin was confirmed by finding, in vitro, a platelet aggregating factor in the presence of Fraxiparine. The literature concerning this topic is reviewed and discussed.