Comparison of techniques for quantifying alkaline phosphatase isoenzymes in canine serum

Three methods for quantifying the steroid-induced and liver isoenzymes of alkaline phosphatase in canine serum were compared on a group of 29 canine serum samples with increased total alkaline phosphatase activity. Levamisole inhibition, heat inactivation, and affinity electrophoresis with densitometry yielded results that correlated strongly. The relationship between levamisole inhibition and heat inactivation test values was a simple linear one, whereas the relationship between their values and those of electrophoresis was better fitted to an exponential model. The levamisole inhibition and heat inactivation tests provided essentially the same information regarding the relative proportions of steroid-induced and hepatic isoenzymes in canine serum; either test was judged practical for routine clinical application.