[Severe early-onset thrombopenia induced by non-fractionated heparin: therapeutic trial with low molecular weight heparin].

A case of severe thrombocytopenia (27 x 10(3)/mm3) of early onset during unfractionated heparin (Héparine sodique Rovi) treatment is reported in a 75 year-old man suffering from a deep vein thrombosis of the right calf. It was not associated with thromboembolic or haemorrhagic complications. A serum heparin-dependent aggregating factor was not detected. Substitution of low molecular weight heparin (Choay Laboratory, CY 222, PM 4 500, 25 000 U anti-Xa/ml) for unfractionated heparin resulted in a progressive normalisation of the platelet count and improvement of the venous thrombosis.