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HelpOrder 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 |
Reject Due To
| Gross hemolysis | OK |
| Gross lipemia | Reject |
| Gross icterus | OK |
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
Method Description
Analytes of interest and deuterated internal standard are extracted, derivatized and analyzed by liquid chromatography tandem mass spectrometry.(Unpublished Mayo method)
Day(s) Performed
Tuesday
Performing Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
82306
82542