While the measurement of alkaline phosphatase activity in serum has been used extensively in diagnosis,1 this activity in urine has not been similarly exploited.2 In 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 method4 has 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,2 acute and subacute glomerulonephritis, nephrotic
Amador E, Zimmerman TS, Wacker WEC. Urinary Alkaline Phosphatase ActivityII. An Analytical Validation of the Assay Method. JAMA. 1963;185(12):953–957. doi:10.1001/jama.1963.03060120063023
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