Clinical Significance
QuestAssureD™ for Infants, 25-Hydroxyvitamin D - While measurements of 25(OH)D provide a good index of circulating Vitamin D activity in patients not suffering from renal disease, for infants less than 3 years of age it is important to remove circulating levels of the inactive c3-epimer of Vitamin D from the sample so that total Vitamin D levels are not falsely elevated. Falsely elevated results could erroneously make the child appear to be within normal limits and result in potential under-treatment. Levels of c3-epimer in older children and adults are usually negligible and do not cause falsely elevated Vitamin D results.
This assay employs advanced liquid chromatography - tandem mass spectrometry, which enables the chromatographic separation of the c3-epimer from 25-OH Vitamin D, thereby allowing accurate measurement in the presence of c3-epimer. While this assay will produce accurate Vitamin D results on patients of any age, it is specifically indicated for infants less than 3 years of age.

Preferred Specimen(s)
0.5 mL serum

Minimum Volume
0.2 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®) at room temperature, centrifuge and remove from the gel within 48 hours.

Transport Container
Transport tube

Transport Temperature
Room temperature

Specimen Stability
Room temperature: 7 days
Refrigerated: 7 days
Frozen: 28 days

Reject Criteria
Gross hemolysis • Grossly lipemic • Plasma • Serum not separated from Serum Separator Tube (SST®) • Serum not separated from 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 specimens are 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)
VIT D, Infants