Excessive fibrinolysis in amyloidosis associated with elevated plasma single-chain urokinase.

Severe bleeding resulting from excessive fibrinolysis has been observed in patients with primary amyloidosis. The authors studied a patient with this hemostatic disorder before and during therapy with epsilon-aminocaproic acid. Excessive fibrinolysis was associated with depressed plasma concentrations of coagulation Factors XII, XI, high-molecular-weight kininogen, and Factors VIII and V; and plasminogen and alpha-2-plasmin inhibitor. These deficiencies were corrected with treatment. The functional and antigenic concentrations of tissue plasminogen activator and plasminogen activator inhibitor in the patient's plasma were normal. Urokinase-type activator activity and antigen were three to five times elevated in the patient's plasma. Results of immunoprecipitation showed that single-chain urokinase-type activator was the primary urokinase-type activator species in the patient's plasma. Excessive fibrinolysis in patients with amyloidosis results from increased plasma single-chain urokinase-type activator activity.