Deficiency of antithrombin III in children with hemolytic-uremic syndrome.

In nine patients with hemolytic-uremic syndrome, the plasma activity and plasma concentrations of antithrombin III were determined on admission to the hospital and during the clinical course of the disease. Hemodialysis was necessary in six of the patients. In seven children the plasma AT III activity was moderately to markedly below the lower limit of normal at 75%, and did not rise after plasmapheresis with fresh frozen plasma. Replacement therapy with AT III concentrate was started in these patients. During the first 2 days an average dose of AT III concentrate of 2.1 U/kg in 24 h was necessary to raise plasma AT III activity by 1%. No side effects were observed. An already pre-existing procoagulant status and the administration of heparin may lead to AT III deficiency in hemolytic-uremic syndrome.