Bone Specific Alkaline Phosphatase (BSAP): BSAP is measured by a solid phase, two-site immunoradiometric assay that specifically measures the skeletal isoenzyme of alkaline phosphatase in serum. Kits are purchased from Hybritech Incorporated (San Diego, CA). The intra-assay and inter-assay variability are 4.2% and 7.2% respectively. The normal range is 8.0 - 16.6 ng/ml for adult women and 7.2 - 15.8 ng/ml for adult men.