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Test Code VITD or LAB2292 Vitamin D (25 Hydroxy), Serum or Plasma

Important Note

Population-based screening for deficiency of this vitamin is not indicated.

Vitamin D deficiency is common in many populations, particularly in patients at higher latitudes, during winter months, and in those with limited sun exposure. Over-the-counter Vitamin D supplements and increased summer sun exposure are sufficient for most otherwise healthy patients. 

Laboratory testing is appropriate in higher-risk patients when results will be used to institute more aggressive therapy (e.g., osteoporosis, chronic kidney disease, malabsorption, some infections, and obese individuals).

Specimen Requirements

Container Type:

Optimal: Gold or Mint*

 

*For STAT requests

Acceptable: Red, or Green

   
Optimal Collection Volume: 

4.5mL; full tube
Minimum Volume:
  • Adults: 1 mL whole blood
  • Neonates: 1 microtainer (400-600 uL)
Collection Instructions:

Gently invert the sample 5-6 times after collection.
Specimen Transport:

Refrigerate
Processing Instructions: 

1. If serum, allow the specimen to clot for 30 minutes.

2. Centrifuge specimen within 2 hours of collection.

3. After centrifugation, specimen tubes without a gel barrier should have the serum or plasma aliquoted to a false bottom container.

4. Keep serum or plasma refrigerated until testing can be performed.

Specimen Stability

Specimen Type Temperature Time
Serum* Refrigerated 4 days
Room Temperature 8 hours
Frozen 6 months

*Note: Heparinized plasma in gel separator tubes is less stable than serum and is only suitable for add-on testing up to 2 days following sample collection.

Specimen Rejection Criteria

Hemolysis Mild OK; Moderate OK; Gross Reject
Lipemia Mild OK; Moderate OK; Gross Reject
Icterus Mild OK; Moderate OK; Gross Reject
Other Quantity not sufficient

Useful For

As an aid in the assessment of vitamin D sufficiency in adults.

 

Note: This assay measures total 25-hydroxy vitamin D, which consists of vitamin D1 and vitamin D3. Vitamin D2 is synthesized by skin exposure to sunlight and is also present in diets and supplements.

Methodology

Roche Cobas chemiluminescent enzyme immunoassay

Reference Ranges

 Test ID  

Reference Range and Reporting Units

VITD

< 10 ng/mL: Deficient

10-29 ng/mL: Insufficient

30-100 ng/mL: Sufficient

> 100 ng/mL: Potential intoxication

 

Please note: Samples with values >240 ng/mL have the test code VD125 (LAB536) auto-reflex ordered. The sample is given to sendouts for Vitamin D testing at Mayo by an LC/MS method. HDN25 is done to confirm a potentially high or toxic level. This is done because there have been a few sporadic cases where an undetermined cross-reactivity has caused an apparent falsely elevated value for this test.

Day(s) Performed

24/7

Expected TAT

Same day

Performing Laboratory

Bronson Laboratory, Chemistry - Kalamazoo and Battle Creek

Sample Retention Time

7 days

CPT Code

82306

LOINC Code

1989-3