Clinical Significance
QuestAssureD™ 25-Hydroxyvitamin D (D2, D3) - Measurement of serum 25-OH vitamin D concentrations provide a good index of circulating vitamin D activity in patients not suffering from renal disease. Lower than normal 25-OH vitamin D levels can result from a dietary deficiency, poor absorption of the vitamin or impaired metabolism of the sterol in the liver. A 25-OH vitamin D deficiency can lead to bone diseases such as rickets and osteomalacia. Above normal levels can lead to hypercalcemia. This assay employs liquid chromatography tandem mass spectrometry to independently measure and report the two common forms of 25-hydroxy vitamin D: 25-OH D3 - the endogenous form of the vitamin and 25-OH D2 - the analog form used to treat 25-OH Vitamin D3 deficiency.

Preferred Specimen(s)
0.5 mL serum

Minimum Volume
0.3 mL

Collection Instructions
Collect blood in a standard red-top serum Vacutainer® tube. Allow blood to clot at room temperature. Centrifuge and separate the serum from the cells immediately.
Alternatively, collect blood in a Serum Separator Tube (SST®), allow to clot at room temperature. Centrifuge and remove from the gel within 48 hours.

Transport Container
Transport tube

Transport Temperature
Room temperature

Specimen Stability
Room temperature: 21 days
Refrigerated: 21 days
Frozen: 21 days

Reject Criteria
Gross hemolysis • Grossly lipemic • Heparinized or EDTA plasma • Serum not separated from Serum Separator Tube (SST®) gel or clot within 48 hours • Grossly icteric

Includes
Vitamin D, 25-OH, Total
Vitamin D, 25-OH, D3
Vitamin D, 25-OH, D2

Patient Preparation
Fasting preferred, but not required

Methodology
Chromatography/Mass Spectrometry

Assay Category
This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by FDA. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

Reference Range(s)
Vitamin D, 25-OH, Total    30-100 ng/mL
Vitamin D, 25-OH, D3    Not established
Vitamin D, 25-OH, D2    Not established

Alternative Name(s)
Vitamin D2, 25-hydroxy,25-Hydroxyergocalciferol (25OHD2),Vitamin D3, 25-hydroxy,D2 Vitamin,25-Hydroxyvitamin D3,25-OH-D3,25-Hydroxycholecalciferol (25OHD3),25-OH-D2,D3 Vitamin,Vit D, LC/MS/MS,25-Hydroxyvitamin D2