Atypical alkaline phosphatase isozymes in serum and urine of patients with renal failure

Abstract

Background: Alkaline phosphatases (ALPs) originating from different organs are frequently detected in the serum and urine of patients with renal failure. Methods: We investigated the characteristics of ALPs in the serum and urine of 108 patients with chronic renal failure (CRF) and of 106 healthy control subjects. Results: In polyacrylamide gel electrophoresis, three atypical ALP bands in serum of patients were designated as atypical-s1, -s2 and -s3, respectively. In contrast, five atypical bands (u1, u2, u3, u4 and u5) were detected in the urine of patients. The atypical ALPs were electrophoretically isolated and assayed to determine their biochemical properties, i.e., neuraminidase sensitivity, heat stability, reactivity to anti-intestinal or anti-tissue nonspecific ALP antibodies, molecular sizes and sugar chain heterogeneities. From these results, we found that atypical-s1 and -s2 were the intestinal-type ALP, while s3 was the tissue-unspecific type ALP. Atypical-u1, -u2 and -u3 were high-molecular type ALPs, which we suggested as the ones that originated from the intestine. Atypical-u4, a tissue-unspecific type ALP, was detected with considerable frequency in the urine of patients. In patients with CRF, the appearance of these atypical ALPs was accompanied by a deterioration of the creatinine clearance. Conclusions: The appearance of atypical ALPs in the serum and urine of patients with CRF may be a useful marker for renal disease.