[Disorders in the conversion of fibrinogen to fibrin in patients with multiple myeloma].

A prolonged thrombin clotting time was found in 15 of 85 patients with multiple myeloma. Among those with abnormal clotting time in 9 cases (60.0%) the M protein was classified as IgG-lambda, in 1 (6.6%) as IgA-lambda, in 2 (13.3%) as IgG-kappa, and in 3 (20.3%) as IgA-kappa. There was no correlation between the prolongation of thrombin time and occurrence of bleeding. The reptilase clotting time was parallel to the thrombin time. The addition of calcium chloride partially corrected both clotting times. The isolated M proteins IgG-lambda and IgG-kappa from patients with prolonged thrombin time at the concentration of 25-50 mg/ml inhibited the polymerization of fibrin monomers but had no effect on the amidolytic and proteolytic action of thrombin.