Clinical chemistry
-
We used quantitative assays to measure the activity of the bone, liver, and intestinal forms of alkaline phosphatase in plasma in 75 patients with endstage chronic renal failure undergoing hemodialysis. The results were correlated with radiological and other biochemical indices of bone disease and with biochemical indices of liver disease. The total activity of alkaline phosphatase in plasma increased in 28 patients. ⋯ Osteocalcin and bone alkaline phosphatase, but not parathyrin, decreased with age, implying that the skeletal response to parathyrin may be age dependent. In patients with increased total alkaline phosphatase undergoing hemodialysis, the concurrent measurement of gamma-glutamyltransferase may help identify whether the enzyme increase originates from the liver or bone, but this approach wrongly identified the source of the increase in three of 28 patients. Therefore, we recommend a separate measurement of the bone isoenzyme of alkaline phosphatase.