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Test Code BAP Bone Alkaline Phosphatase, Serum

Reporting Name

Bone Alkaline Phosphatase, S

Useful For

Diagnosis and assessment of severity of metabolic bone disease including Paget disease, osteomalacia, and other states of high bone turnover

 

Monitoring efficacy of antiresorptive therapies including postmenopausal osteoporosis treatment

 

The assay is not intended as a screening test for osteoporosis.

 

Measurements of bone turnover markers are not useful for the diagnosis of osteoporosis; diagnosis of osteoporosis should be made based on bone density.

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Serum


Specimen Required


Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 0.6 mL

Collection Instructions: Centrifuge and aliquot serum into plastic vial.


Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 14 days
  Frozen  90 days
  Ambient  7 days

Reference Values

Males

<2 years: 25-221 mcg/L

2-9 years: 27-148 mcg/L

10-13 years: 35-169 mcg/L

14-17 years: 13-111 mcg/L

Adults: ≤20 mcg/L

 

Females

<2 years: 28-187 mcg/L

2-9 years: 31-152 mcg/L

10-13 years: 19-177 mcg/L

14-17 years: 7-41 mcg/L

Adults

Premenopausal: ≤14 mcg/L

Postmenopausal: ≤22 mcg/L

Day(s) Performed

Monday through Saturday

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

84080

LOINC Code Information

Test ID Test Order Name Order LOINC Value
BAP Bone Alkaline Phosphatase, S 17838-4

 

Result ID Test Result Name Result LOINC Value
BAP Bone Alkaline Phosphatase, S 17838-4

Clinical Information

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.(1)

 

Normal bone is constantly undergoing remodeling 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, kidney failure, gastrointestinal diseases, long-term corticosteroid therapy, multiple myeloma, and cancer metastatic to the bones.(2)

 

Paget disease is another common metabolic bone disease caused by excessive rates of bone remodeling 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.

Interpretation

Bone alkaline phosphatase (BAP) concentration is high in Paget disease and osteomalacia.(3)

 

Antiresorptive therapies lower BAP from baseline measurements in Paget disease, osteomalacia, and osteoporosis. Several studies have shown that antiresorptive therapies for management of osteoporosis patients should result in at least a 25% decrease in BAP within 3 to 6 months of initiating therapy.(4,5) BAP also decreases following antiresorptive therapy in Paget disease.(6)

 

When used as a marker for monitoring purposes, it is important to determine the critical difference (or least significant change). The critical difference is defined as the difference between 2 determinations that may be considered to have clinical significance. The critical difference for this method was calculated to be 25% with a 95% confidence level.(1)

Method Description

The instrument used is a Beckman Coulter Unicel DXI 800. The Access Ostase assay is a one-step immunoenzymatic assay used to measure bone alkaline phosphatase (BAP) in human serum. The assay utilizes a mouse monoclonal antibody specific to BAP and paramagnetic particles coated with goat antimouse antibodies. BAP in the patient's specimen binds to the anti-BAP mouse antibody, which in turn is captured by the solid phase antimouse antibody. After washing to remove any unbound material, a chemiluminescent substrate is added to the reaction vessel. The BAP present acts on the substrate to produce light, which is measured with a luminometer. The amount of light produced is directly proportional to the amount of BAP in the specimen. The amount of analyte in the specimen is determined from a stored, multipoint calibration curve.(Package insert: Access Ostase. Beckman-Coulter; 2019)

Reject Due To

Gross hemolysis Reject
Gross lipemia OK

Method Name

Immunoenzymatic Assay

Secondary ID

82985