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HelpTest ID 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.
Secondary ID
63416Useful For
As a screening test for inactivating CYP24A1 variants in patients with symptoms, signs, or biochemical findings of parathyroid hormone-independent hypercalcemia or hypercalciuria
Specimen Type
SerumSpecimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| 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
Day(s) Performed
Tuesday
Report Available
2 to 15 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
82306
82542