Clinical use
Bone Specific Alkaline Phosphatase is used to diagnose and assess the severity of metabolic bone disease including Paget disease, osteomalacia, and other states of high bone turnover. The test can monitor efficacy of antiresorptive therapies including postmenopausal osteoporosis treatment.
Background
Bone alkaline phosphatase (BAP) is the bone-specific isoform of alkaline phosphatase. A glycoprotein that is found on the surface of osteoblasts, BAP reflects the biosynthetic activity of these bone-forming cells. BAP has been shown to be a sensitive and reliable indicator of bone metabolism.
Normal bone is constantly undergoing remodelling in which bone degradation or resorption is balanced by bone formation. This process is necessary for maintaining bone health. If the process becomes uncoupled and the rate of resorption exceeds the rate of formation, the resulting bone loss can lead to osteoporosis and, consequently, a higher susceptibility to fractures.
Osteoporosis is a metabolic bone disease characterized by low bone mass and abnormal bone microarchitecture. It can result from a number of clinical conditions including states of high bone turnover, endocrine disorders (primary and secondary hyperparathyroidism and thyrotoxicosis), osteomalacia, renal failure, gastrointestinal diseases, long-term corticosteroid therapy, multiple myeloma, and cancer metastatic to the bones.
Paget disease is another common metabolic bone disease caused by excessive rates of bone remodelling resulting in local lesions of abnormal bone matrix. These lesions can result in fractures or neurological involvement. Antiresorptive therapies are used to restore the normal bone structure.
Reference ranges
Age dependent. Check referral report
Patient preparation
None required
Specimen requirements
Serum SST or Plain (red top)
Turnaround time
1 week
Referred test
Referred test
Location
Northern General Hospital