SECONDARY RESISTANCE TO COUMARIN DERIVATI VES IN A PATIENT WITH A HYPERCOAGULABILITY SYNDROME

History and clinical findings: A 23-year-old woman with deep (leg) vei n thrombosis was hospitalised because the Quick value had not decrease d despite administration of phenprocoumon. Two years previously she ha d sustained an anterior wall myocardial infarction and a scar on her r ight kidney had been an incidental sonographic finding. There was blui sh, fine reticular discoloration over the toes of both legs. Physical examination was otherwise unremarkable except for obesity. Investigati ons: The concentration of creatine kinase was raised to 250 U/l and th at of lactate dehydrogenase to 300 U/l. The platelet count was decreas ed to 75/nl. The level of IgG anticardiolipin antibodies was raised (2 04 U/l) and the test for lupus anticoagulant positive. A biopsy of the skin from a toe revealing livedoid vasculitis, primary antiphospholip id syndrome (PAPS) was diagnosed. Treatment and course: Noncompliance, excessive vitamin K ingestion, drug interaction and malabsorption wer e excluded as ca use of the lacking action of phenprocoumon. Despite a nti coagulation with high-dosage low-molecular heparin and inhibition of platelet aggregation with ticlopidine and finally also immunosuppre ssive treatment with cyclophosphamide, skin necroses developed on the toes and she had recurrent pulmonary embolisms of which she died. Conc lusion: Standard treatment of PAPS is effective anticoagulation with c oumarin derivatives. Secondary resistance to coumarin is a rare occurr ence: its cause remains unknown.