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Test 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.


Reporting Name

25HDN:24,25 Dihydroxy VitD Ratio, S

Specimen Type

Serum

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 14 days
  Frozen  30 days
  Ambient  7 days

Report Available

2 to 15 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

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

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

Day(s) Performed

Tuesday

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

Specimen Minimum Volume

1.1 mL

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 Name

Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)

Portions of this test are covered by patents held by Quest Diagnostics

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