The importance of urinary thromboxane B2 excretion in the diagnosis of acute renal rejection.

To establish whether or not urinary excretion TxB2 is a useful parameter in the diagnosis of acute renal rejection, 45 renal transplant patients were studied and classified in four groups: Group A. Ten observations of satisfactory clinical outcome (without either acute rejection or tubular necrosis). Urinary TxB2 was initially increased but had settled to normal by the 3rd postoperative day. Two patients had subsequent increases. Group B. Twenty-five episodes of acute rejection on a previously satisfactorily functioning graft. Nineteen had increases in TxB2 values before serum creatinine increased. Group C. Five episodes of tubular necrosis without acute rejection. The evolution was similar to Group A. Group D. Nine acute episodes of rejection on kidneys with tubular necrosis. The urinary output of TxB2 was increased from the beginning. This increase was maintained until the rejection was treated. This group had the highest values of urine TxB2. The principal significance of this parameter lies in its precocity and in its utility for diagnosis of acute rejection in the graft with tubular necrosis, as the persistence of raised values of TxB2 in the urine beyond the 3rd postoperative day is highly suggestive of an acute rejection.