Fibrinogen Degradation Products in Serum and Urine of Patients with Systemic Lupus Erythematosus. Relation to Renal Disease and Pathogenetic Mechanism

Serum and concentrated urine from blood donors, patients with rheumatoid arthritis and SLE patients with and without renal disease were tested for the presence of fibrinogen degradation products (FDP), using the tanned red cell hemagglutination inhibition immunoassay. The majority of blood donors had serum titers of 1:2 to 1:4, while the majority of patients with rheumatoid arthritis and systemic lupus erythematosus had titers of 1:8 to 1:32. FDP were detected in low titers in urine of nearly all blood donors, patients with rheumatoid arthritis and SLE patients without renal disease, whereas elevated titers were found in SLE patients with active renal disease. Several possible sources of the urinary FDP are discussed, and the role of fibrin deposition in glomerular injury is reviewed.