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25-Hydroxyvitamin D2 and D3, Serum

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Updated Test Information:

Test Description
25-Hydroxyvitamin D2 and D3, Serum
Synonym(s)

25-Hydroxy D2; 25-Hydroxy D3; 25-Hydroxy Vitamin D; 25-Hydroxycholecalciferol; 25-Hydroxyergocalciferol; 25-OH Vitamin D; Calcidiol; D2; D3; Vitamin D Assay; 25HDN; 25OHD; 25DEP; Calciferol; Ergocalciferol; Cholecalciferol; Colecalciferol; CYP2R1
Test ID
25HDN
Performing Lab

Labcorp
General Information

Useful for:



  • Diagnosis of vitamin D deficiency

  • Differential diagnosis of rickets and osteomalacia

  • Monitoring vitamin D replacement therapy

  • Diagnosis of hypervitaminosis D
Container Type

Red-top tube, gel-barrier tube, lavender-top (EDTA) tube or green-top (heparin) tube
Specimen Type

Serum
Specimen Requirements

  • Preferred: Serum Gel

  • Acceptable: Red top tube
Minimum Sample Volume

0.25 mL
Stability

  • Refrigerated (preferred): 14 days

  • Frozen: 30 days

  • Ambient: 7 days
Limitations

Long term use of anticonvulsant medications may result in vitamin D deficiency that could lead to bone disease; the anticonvulsants most implicated are phenytoin, phenobarbital, carbamazepine, and valproic acid. Newer antiseizure medications have not been studied or are not thought to contribute to vitamin D deficiency.
Methodology

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

2-5 days
Testing Schedule

Monday-Friday
Test Includes

  • 25-Hydroxy D2

  • 25-Hydroxy D3

  • 25-Hydroxy D Total
Retention

2 weeks
CPT Code(s)

82306
Reference Range

TOTAL 25-HYDROXYVITAMIN D2 AND D3 (25-OH-VitD)

Value (ng/mL) Interpretation
<10 Severe Deficiency*
10 - 19 Mild to Moderate Deficiency**
20 - 50 Optimum Level***
51 - 80 Increase Risk of Hypercalciuria****
>80 Toxicity Possible*****

*Could be associated with osteomalacia or rickets

**May be associated with increased risk of osteoporosis or secondary hyperparathyroidism

***Optimum levels in the healthy population, patients with bone disease may benefit from higher levels within this range

****Sustained levels >50 ng/mL 25OH-VitD along with prolonged calcium supplementation may lead to hypercalciuria and decreased renal function

*****80 ng/mL is the lowest reported level associated with toxicity in patients without primary hyperparathyroidism who have normal renal function. Most patients with toxicity have levels >150 ng/mL. Patients with renal failure can have very high 25-OH-VitD levels without any signs of toxicity, as renal conversion to the active hormone 1,25-OHVitD is impaired or absent.

These reference ranges represent clinical decision values, based on the 2011 Institute of Medicine report, that apply to males and females of all ages, rather than population-based reference values. Population reference ranges for 25-OH-VitD vary widely depending on ethnic background, age, geographic location of the studied populations, and the sampling season. Population-based ranges correlate poorly with serum 25-OH-VitD concentrations that are associated with biologically and clinically relevant vitamin D effects and are therefore of limited clinical value.
LOINC Code(s)

49054-0, 1989-3, 62292-8
Additional Information