Urinary Alkaline Phosphatase Activity

Abstract

While the measurement of alkaline phosphatase activity in serum has been used extensively in diagnosis,¹this activity in urine has not been similarly exploited.²In fact, significant alkaline phosphatase activity has not previously been found in normal human urine.^{2, 3}The present study demonstrates that alkaline phosphatase activity occurs in urine from both normal and abnormal individuals, but that it is masked by the presence of a dialyzable inhibitor(s). By the use of dialyzed urine, the p-nitrophenyl phosphate assay method⁴has been modified to yield a simple, precise assay for the measurement of alkaline phosphatase activity in dialyzed human urine. Through the use of this method, the normal range of activities has been established. Moreover, the measurement of urinary alkaline phosphatase activity may be employed as an aid in the diagnosis of diseases of the renal parenchyma, including renal adenocarcinomas,²acute and subacute glomerulonephritis, nephrotic