Lipoprotein (a): its role in childhood thromboembolism.

PURPOSE Elevated lipoprotein (a) [LP (a)] concentrations are independent risk factors of coronary heart disease or stroke in young adults. To clarify its role in childhood thromboembolism, Lp (a) was measured in 72 children with thromboembolism. METHODS In addition to Lp (a), defects of the protein C anticoagulant system, antithrombin, and antiphospholipid antibodies were investigated in children with arterial (n = 36) or venous (n = 36) thrombosis. RESULTS Enhanced Lp (a) >50 mg/dL was diagnosed in 8 out of 36 children with arterial and 5 out of 36 patients with venous thrombosis. Of the 72 children, 25 showed the factor V Leiden mutation, 10 showed protein C deficiency, 2 showed antithrombin deficiency, and 4 showed primary antiphospholipid syndrome. Three children with increased Lp (a) were heterozygous for the factor V Leiden mutation, and 1 girl showed additional protein C deficiency. CONCLUSIONS Data of this study indicate that increased concentrations of Lp (a) play an important role in childhood thrombosis.