Fibrin degradation products in renal diseases.

Levels of serum fibrin degradation products (FDP) were determined in patients with acute nephritis, chronic nephritis, lupus nephritis and toxemia of pregnancy by the passive hemagglutination inhibition test. Serum FDP levels were less than 10 mug/ml in normal control adults, averaging 3.2 +/- 1.2 mug/ml. The incidence of serum FDP positive patients (more than 10 mug/ml) in those with acute nephritis, chronic nephritis, lupus nephritis and toxemia of pregnancy was 28%, 73%, 100% and 100%, respectively. Their serum FDP levels averaged 8.4 +/- 5.6 mug/ml, 16.0 +/- 5.9 mug/ml, 21.4 +/- 7.6 mug/ml and 35 mug/ml, respectively. Plasma fibrinogen levels, prothrombin time, partial thromboplastin time, euglobulin lysis time and platelet counts were within normal limits in serum FDP positive patients with renal diseases, indicating that there was no severe disseminated intravascular coagulation. All FDP positive patients with renal diseases of immunological origin demonstrated the deposition of fibrin within glomeruli with complement and immunoglobulin deposits. However, FDP positive patients with toxemia of pregnancy demonstrated fibrin depositions within glomeruli without complement and immunoglobulin deposits. FDP D fragments of urine from lupus nephritis patients showed no changes in immunoelectrophoretic patterns by heat treatment, indicating that urine FDP was derived from secondary fibrinolysis.