A simple test for early detection of severe renal homograft rejection

Adding urine to a standard buffered fibrinogen solution and then coagulating it with thrombin gives reproducible coagulation times with normal urines. Coagulation of fibrinogen by thrombin is prolonged in acid solutions with a pH below six. Urines of high acidity lower the buffer pH of the fibrinogen solution below a value of six thus rendering the system uncoagulable or significantly prolonging the coagulation time. With this test system we found that out of 16 severe homograft rejections 15 were accompanied by a high acid excretion in six-hour urine specimens. Ten of these acid episodes became apparent 12 to 48 hr before clinical symptoms and before elevation of the serum creatinine could be detected.