An acquired cryoglobulinemia which inhibits fibrin polymerization in a patient with IgG kappa myeloma.

A 58-year-old man with multiple myeloma and paraproteinemia (IgG kappa) acquired cryoglobulinemia 2 years after the initial diagnosis of the disease. This cryoglobulin interfered specifically with fibrin aggregation. The patient's fibrinogen was functionally normal; however, clotting times (thrombin clotting time, reptilase clotting time) were prolonged in the untreated plasma and in the supernatant after removal of the cryoglobulins. Untreated patient's serum, and even more pronounced, the cryoprecipitate inhibited the association of fibrin monomers obtained from healthy controls. The inhibitory activity on fibrin aggregation diminished upon treatment-induced reduction of plasma protein levels.