UW Hospital and Clinics Lab Test Directory
| Test Name: |
|
Vitamin D, 25-Hydroxy by HPLC
|
|
|
|
|
|
|
| Test Code(s): |
|
LCD25 / HCLCD25
|
|
|
|
|
|
|
| CPT Code(s): |
|
82306
|
|
|
|
|
|
|
| Test Description: |
|
Test Component: Total 25-Hydroxy Vitamin D, 25-Hydroxy Vitamin D2 and 25-Hydroxy Vitamin D3
|
|
|
|
|
|
|
| Methodology: |
|
Liquid Chromatography
|
|
|
|
|
|
|
| Days Performed: |
|
Mon-Fri, dayshift.
|
|
|
|
|
|
|
| Turnaround Time: |
|
Routine: 4 - 7 days.
|
|
|
|
Specimen Requirements
|
|
|
|
| Specimen: |
|
Blood
|
|
|
|
|
|
|
| Collection Container: |
|
Preferred: Red top
|
|
|
|
|
|
|
| Collection Volume: |
|
Preferred: 5 mL
Pediatrics: 1 mL
|
|
|
|
|
|
|
| Sample Analyzed: |
|
Serum
|
|
|
|
|
|
|
| Volume Required: |
|
Preferred: 1 mL
Pediatrics: 0.5 mL
|
|
|
|
|
|
|
| Specimen Processing: |
|
Centrifuge. Transfer cell-free serum to plastic vial. Refrigerate.
|
|
|
|
|
|
|
| Specimen Transport: |
|
Transport specimen to UWHC Core Laboratory (B4/220). Transport with coolant pack if coming from outreach location.
|
|
|
|
|
|
|
| Unacceptable Criteria: |
|
Specimens collected in red cap with yellow ring (SST) tubes are not acceptable.
|
|
|
|
|
|
|
| Stability: |
|
Refrigerated: 2 weeks
Frozen: 6 months
|
|
|
|
Interpretation
|
|
|
|
|
Reference Interval:
|
|
|
Vitamin D status in a patient is judged by
Total 25-0H Vitamin D
|
| Total 25-hydroxy Vitamin D clinical reference values: |
| < 10 ng/mL |
Severe deficiency |
| 10-29 ng/mL |
Mild to moderate deficiency |
| 30-80 ng/mL |
Optimum levels |
| > 80 ng/mL |
Toxicity possible |
|
|
|
|
|
|
|
| Test Limitations: |
|
Patients treated with Atovaquone may exhibit a falsely elevated 25-OH Vitamin D2 level regardless of whether the patient is receiving Vitamin D2 (ergocalciferol) therapy.
|
|
|
|
|
|
|
| Additional Information: |
|
A patient's vitamin D status should be judged by the total 25-Hydroxy vitamin D which is equal to the combined 25-Hydroxy D2 and 25-Hydroxy D3 levels. Vitamin D by HPLC (UV) quantitates both the D2 and D3 forms of the hydroxylated vitamin. D3 is the endogenous form of the vitamin that is derived from sunlight and the conversion of cholestane to cholecalciferol which is subsequently converted by the liver to 25-Hydroxy D3. Occasionally, D3 (cholecalciferol) is found in multi-day vitamin preparations but not in concentrations that achieve therapeutic doses required for treating osteoporosis. Whereas, D2 (ergocalciferol) is an exogenous form derived from plant sources and generally reflects supplementation. Levels of 25-Hydroxy vitamin D3 vary seasonally, especially in the northern climate of Wisconsin.
This test was developed and its performance characteristics determined by the UWHC Clinical Laboratories. This test meets the standards for clinical testing. This test should not be regarded as investigational or for research use. The US Food and Drug Administration (FDA) has not approved or cleared this test; however, the FDA has determined that such clearance or approval is not necessary.
|
D25,
Vitamin D2,
Vitamin D3
|
