ABSTRACT
The alkaline phosphatase [ALP] enzyme has several isoenzymes in different tissues. Bone and liver isoenzymes are abundant and prominent. The purpose of this study was to develope and compare the heat inactivation and urea inhibition methods in measurement of bone and liver alkaline phosphatase isoenzymes. Determination of total ALP activity of liver and bone isoenzymes was carried out for several times per day and during consecutive days. Precision and reliability of these methods were confirmed after 10 times repeat of all experiments on two normal, one liver cholestase and one bone paget's serum samples. Then it was set up heat inactivation and urea methods in biochemistry laboratory of Babol University of Medical Sciences. In addition to, on 50 normal serum samples of adolescents, determination of total ALP activity by AACC- IFCC standard method and bone and liver isoenzymes was carried out by heat inactivation and urea inhibition methods. The results of bone and liver isoenzymes activity by heat inactivation and urea inhibition methods were about in mean +/- 1SD intervals. CVs of heat inactivation method for liver and bone isoenzymes were 3.17 and 3.73 and CVs of urea inhibition method for liver and bone isoenzymes were 3.33 and 4.46, respectively. Comparison of urea inhibition method with heat inactivation method, demonstrated a good coefficient of correlation for liver [r = 0.964] and bone [r = 0.961] isoenzymes. The heat inactivation and urea inhibition methods are cheap and had acceptable precision and reliability and good accuracy. These methods are useful for determination of ALP isoenzymes especially when bone and liver are involved