Quantification and comparison of bone-specific alkaline phosphatase with two methods in normal and paget’s specimens

Background: Bone-specific alkaline phosphatase (BAP) is synthesized by the osteoblasts and is presumed to be involved in the calcification of bone matrix, though its precise role in the formation process is unknown. The aim of the present study was to measure the BAP activity in Pagetʹs and normal specimens by two different techniques. Methods: Total ALP (TAP) as well as BAP activity-measuring tests were repeatedly undertaken at different times during the day and different days on the serum samples (inter and intra assay). Precision and repeatability of the phenylalanine inhibition (PHI) and heat inactivation (HI) techniques were approved during ten times repetition of all the tests on two normal samples besides one sample from Pagetʹs disease of bone. The measurement of TAP and BAP activities was also carried out on 50 serum samples from normal adults using the standard IFCC-AACC and the established methods, respectively. Results: Coefficients of Variation (CV) for intra-assay of BAP were 2.33% and 3.16% by HI and PHI methods, respectively. Also, the inter-assay CV of BAP was 2.87% and 3.49% for mentioned methods in Pagetʹs sample, respectively. In addition, the correlation of HI and PHI methods was found to be r= +0.873 for bone-specific isoenzyme. Conclusion: Regarding the appropriate precision, repeatability and correlation of HI and PHI techniques, as well as their cost effectiveness can be of use in the quantification of bone alkaline phosphatase isoenzyme activity, especially when bone is involved.