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HelpTest Code OSCAL Osteocalcin, Serum
Reporting Name
Osteocalcin, SUseful For
Monitoring and assessing effectiveness of antiresorptive therapy in patients treated for osteopenia, osteoporosis, Paget disease, or other disorders in which osteocalcin levels are elevated
As an adjunct in the diagnosis of medical conditions associated with increased bone turnover, including Paget disease, cancer accompanied by bone metastases, primary hyperparathyroidism, and renal osteodystrophy
This test is not useful for the diagnosis of osteoporosis.
Method Name
Electrochemiluminescence Immunoassay (ECLIA)
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumSpecimen Required
Patient Preparation:
1. Fasting (12 hours)
2. For 12 hours before specimen collection do not take multivitamins or dietary supplements containing biotin (vitamin B7), which is commonly found in hair, skin, and nail supplements and multivitamins.
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot serum into plastic vial.
Specimen Minimum Volume
0.75 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 14 days | |
| Frozen | 90 days | ||
| Ambient | 72 hours |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | OK |
| Gross icterus | OK |
Reference Values
Males
<5 years: 19-75 ng/mL
5-9 years: 21-108 ng/mL
10-15 years: 19-159 ng/mL
16-17 years: 12-114 ng/mL
≥18 years: 9-42 ng/mL
Females
<5 years: 14-126 ng/mL
5-9 years: 16-152 ng/mL
10-15 years: 15-151 ng/mL
16-17 years: 9-70 ng/mL
≥18 years: 9-42 ng/mL
Day(s) Performed
Monday through Saturday
CPT Code Information
83937
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| OSCAL | Osteocalcin, S | 2697-1 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| OSCAL | Osteocalcin, S | 2697-1 |
Clinical Information
Osteocalcin, the most important noncollagen protein in bone matrix, accounts for approximately 1% of the total protein in human bone. It is a 49-amino acid protein with a molecular weight of approximately 5800 Da. Osteocalcin contains up to 3 gamma-carboxyglutamic acid residues as a result of posttranslational, vitamin K-dependent enzymatic carboxylation. Its production is dependent upon vitamin K and is stimulated by 1,25 dihydroxy vitamin D.
Osteocalcin is produced by osteoblasts and is widely accepted as a marker of bone osteoblastic activity. Osteocalcin, incorporated into the bone matrix, is released into the circulation from the matrix during bone resorption and, hence, is considered a marker of bone turnover rather than a specific marker of bone formation. Osteocalcin levels are increased in metabolic bone diseases with increased bone or osteoid formation, including osteoporosis, osteomalacia, rickets, hyperparathyroidism, renal osteodystrophy, thyrotoxicosis, and in individuals with fractures, acromegaly, and bone metastasis. By means of osteocalcin measurements, it is possible to monitor therapy with antiresorptive agents (bisphosphonates or hormone replacement therapy) in, for example, patients with osteoporosis or hypercalcemia.(1) Decrease in osteocalcin is also observed in some disorders (eg, hypoparathyroidism, hypothyroidism, and growth hormone deficiency).
Immunochemical and chromatographic studies have demonstrated considerable heterogeneity for concentrations of circulating osteocalcin in normal individuals and in patients with osteoporosis, chronic kidney failure, and Paget disease. Both intact osteocalcin (amino acids 1-49) and the large N-terminal/midregion (N-MID) fragment (amino acids 1-43) are present in blood. Intact osteocalcin is unstable due to protease cleavage between amino acids 43 and 44. The N-MID fragment, resulting from cleavage, is considerably more stable. This assay detects both the stable N-MID fragment and intact osteocalcin.
Interpretation
Elevated levels of osteocalcin indicate increased bone turnover.
In patients taking antiresorptive agents (bisphosphonates or hormone replacement therapy), a decrease of 20% or less from baseline osteocalcin level (ie, prior to the start of therapy) after 3 to 6 months of therapy suggests effective response to treatment.(2)
Patients with diseases, such as hyperparathyroidism, which can be cured, should have a return of osteocalcin levels to the reference range within 3 to 6 months after complete cure.(3)
Cautions
Measurements of bone turnover markers are not useful for the diagnosis of osteoporosis, which should be made on the basis of bone density or clinical history of low-trauma fracture.
Osteocalcin is cleared by the kidneys; therefore, elevations may be observed in patients with impaired kidney function without increased bone turnover.
Serum osteocalcin may not reflect bone formation in patients treated with the hormone 1,25-dihydroxy vitamin D or those with abnormalities in that hormone since osteocalcin is regulated by 1,25-dihydroxy vitamin D.
In rare cases, some individuals can develop antibodies to mouse or other animal antibodies (often referred to as human anti-mouse antibodies [HAMA] or heterophile antibodies), which may cause interference in some immunoassays. The presence of antibodies to streptavidin or ruthenium can also rarely occur and may also interfere in this assay. Caution should be used in interpretation of results, and the laboratory should be alerted if the result does not correlate with the clinical presentation.
In rare cases, interference due to extremely high titers of antibodies to ruthenium or streptavidin can occur.
Method Description
The Roche Osteocalcin assay is a 2-site immunometric (sandwich) assay using electrochemiluminescence detection. Patient specimen, biotinylated monoclonal N-terminal/midregion (N-MID) osteocalcin-specific antibody, and monoclonal N-MID osteocalcin-specific antibody labeled with ruthenium react to form a complex. Streptavidin-coated microparticles act as the solid phase to which the complex binds. Voltage is applied to the electrode, inducing a chemiluminescent emission from the ruthenium, which is then measured against a calibration curve to determine the amount of osteocalcin in the patient specimen.(Package insert: Elecsys N-MID Osteocalcin. Roche Diagnostics; V 1.0 English, 01/2020)