Fibrinogen catabolism in patients with type II and type IV hyperlipidemia. Effect of dietary and clofibrate treatment on laboratory findings.

Fibrinogen catabolism was studied by plasma fibrinogen chromatography and other methods in 99 subjects with hyperlipoproteinemia Types IIa, IIb, and IV, and in 24 control subjects with normal blood lipid values. Subjects with either a history of thromboembolic vascular disease or clinical evidence of atherosclerosis were excluded. Type II subjects (i.e., the combined group of Type IIa and IIb subjects) showed an elevation of plasma high molecular weight fibrinogen complexes, which is indicative of enhanced fibrin formation. They also showed an elevation of fibrinogen-first-derivative, which is indicative of fibrinogenolysis and increased plasma euglobulin activity. Subjects with Type IV hyperlipoproteinemia showed similar findings to those of Type II except that high molecular weight fibrinogen complex concentration was normal. Subsequently, 36 patients received a fat-controlled, low cholesterol diet and were studied in a blind, random, crossover study of dietary vs clofibrate treatment. Although total cholesterol and triglyceride levels fell significantly during the treatment periods, chromatographic findings of abnormal plasma fibrinogen remained unchanged.