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HelpTest Code 2425D 25-Hydroxyvitamin D:24,25-Dihydroxyvitamin D Ratio, Serum
Ordering Guidance
The preferred initial test for assessing vitamin D status and most accurately reflects the body's vitamin D stores is the 25-hydroxyvitamin D test; order 25HDN / 25-Hydroxyvitamin D2 and D3, Serum.
In the presence of kidney disease or hypercalcemia, testing of 1,25-dihydroxy vitamin D may be needed to adequately assess vitamin D status; order DHVD / 1,25-Dihydroxyvitamin D, Serum.
Specimen Required
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1.7 mL
Collection Instructions: Within 2 hours of collection, centrifuge and aliquot serum into a plastic vial.
Useful For
As a screening test for inactivating CYP24A1 variants in patients with symptoms, signs, or biochemical findings of parathyroid hormone-independent hypercalcemia or hypercalciuria
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| 2425R | 24,25 Dihydroxy Vitamin D | No | Yes |
| 25HDN | 25-Hydroxyvitamin D2 and D3, S | Yes | Yes |
Method Name
Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
Portions of this test are covered by patents held by Quest Diagnostics
Reporting Name
25HDN:24,25 Dihydroxy VitD Ratio, SSpecimen Type
SerumSpecimen Minimum Volume
1.1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 14 days | |
| Frozen | 30 days | ||
| Ambient | 7 days |
Reference Values
Interpretative commentary provided based on 25-hydroxyvitamin D (25HDN) to 24,25-dihydroxyvitamin D (24,25D) ratio result.
25HDN to 24,25D Ratio
<25: Normal; also be observed in heterozygous carriers of CYP24A1 variants
25-80: Seen in patients with low vitamin D or heterozygous CYP24A1 variants
>80: Indicate probable biallelic CYP24A1 variant or deletion
Day(s) Performed
Tuesday
Report Available
2 to 8 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
82306
82542
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| 2425D | 25HDN:24,25 Dihydroxy VitD Ratio, S | 94674-9 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 2897 | 25-Hydroxy D2 | 49054-0 |
| 63416 | 25HDN:24,25 Dihydroxy VitD Ratio, S | 94673-1 |
| 2898 | 25-Hydroxy D3 | 1989-3 |
| 83670 | 25-Hydroxy D Total | 62292-8 |
| 90601 | 24,25-Dihydroxy VitD Total | 94672-3 |