Lab Test

Vitamin D, 25 Hydroxy

Test Codes

Antrim #30775, EPIC: LAB5845, D25OH

Specimen Collection Criteria

Collect: One Gold-top SST tube. (Minimum Whole Blood: 4.0 mL)

Physician Office/Draw Specimen Preparation

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Refrigerate (2-8°C or 36-46°F) the centrifuged collection tube within two hours of collection. (Minimum Serum: 1.0 mL)

Preparation for Courier Transport

Transport: Centrifuged collection tube, refrigerated (2-8°C or 36-46°F). (Minimum Serum: 1.0 mL)

Rejection Criteria

Plasma specimens.

Severely lipemic, icteric, or grossly hemolyzed specimens.

In-Lab Processing

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Room temperature is acceptable for a maximum of two hours. (Minimum Serum: 1.0 mL)

Storage

Specimen Stability for Testing:

Centrifuged SST Tubes, Red-top Tubes, and Microtainers®
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 3 months

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days

Laboratory

Canton Chemistry Laboratory
Dearborn Chemistry Laboratory
Farmington Hills Chemistry Laboratory 
Grosse Pointe Chemistry Laboratory 
Royal Oak Automated Chemistry Laboratory 
Troy Chemistry Laboratory
Taylor Chemistry Laboratory
Trenton Chemistry Laboratory
Wayne Chemistry Laboratory

Performed

Farmington Hills
Sunday – Saturday.
Results available within 24 hours.

Royal Oak
Monday – Friday.
Results available within 2 business days.

Grosse Pointe Chemistry Laboratory 
Troy Chemistry Laboratory

Reference Range

  • Less than 10 ng/mL (severe deficiency).
  • 10-29 ng/mL (mild to moderate deficiency).
  • 30-100 ng/mL (optimum levels).
  •  Greater than 100 ng/mL (toxicity possible).

The Abbott Architect Immunoassay for 25-OH Vitamin D underestimates D2  concentration by up to 50%. For patients who are prescribed high-dose  Vitamin D2 and whose result does not correlate with treatment, please  contact Client Services at 1-800-551-0488. 

Test Methodology

Chemiluminescence Immunoassay.

Interpretation

Recent literature suggests that optimal bone health is achieved when the circulating 25-OH vitamin D level is maintained at levels greater than 32 ng/mL.

Patients with 25-OH vitamin D less than 25 ng/mL have an increased risk of secondary hyperparathyroidism, reduced bone mineral density and fractures. Levels less than 10 ng/mL are associated with more severe abnormalities including inadequate mineralization (rickets in children and osteomalacia in adults). Toxic effects may be seen with serum 25-OH vitamin D levels greater than 80 ng/mL although they are more likely to be encountered when the level is greater than 150 ng/mL.

Although 25-OH vitamin D is not the active hormone it is the most useful form of vitamin D for assessment of vitamin D stores. Levels below 25 ng/mL are now considered to be low.

Clinical Utility

This assay is used to diagnose vitamin D deficiency and aids in the differential diagnosis of hypo and hypercalcemia. Increased vitamin D levels may lead to hypertension, nephrolithiasis, and metastatic calcifications.

CPT Codes

82306
LOINC:  1989-3

Contacts

Last Updated

7/28/2021

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