Serial estimation of urinary fibrin fibrinogen degradation products in kidney transplantation.

The urinary excretion of fibrin/fibrinogen degradation products (F.D.P.) of 81 human cadaver kidney transplants has been measured serially by the techniques of tanned red cell haemagglutination inhibition immunoassay and immunonephelometry. Acute rejection episodes in functioning transplants have been associated with increased F.D.P. excretion which in 80% of cases has preceded clinical diagnosis by periods of one to seven days. Recovery from these episodes has been associated with a rapid fall of F.D.P. excretion to undetectable levels. The level of F.D.P. excretion during a rejection episode is a guide to its ultimate outcome. Irreversibly rejected kidneys excrete high levels of F.D.P. for long periods. Viable kidney transplants with prolonged oliguric phases can be distinguished, while still oliguric, from rejected kidneys by their low F.D.P. excretion. F.D.P. cannot usually be detected in the urine of well-functioning transplants. Episodes of raised F.D.P. excretion in the absence of acute clinical rejection, however, occur occasionally and may be associated with permanent impairment of renal function.