QuestAssureD 25-Hydroxy^TM and Calcitriol 1,25 Dihydroxyvitamin D

VITDP or 16761

Includes QuestAssureD 25-Hydroxyvitamin D (D2, D3) and Vitamin D, 1,25-Dihydroxy

Fasting preferred, but not required.
  
Collect blood in a non-gel barrier red-top tube. Allow blood to clot (30 minutes) at room temperature. Centrifuge and separate the serum from the cells.

Alternatively, collect blood in a Serum Separator Tube (SST), allow to clot at room temperature. Centrifuge and remove from the gel.

Note: If sample is submitted with less than 1.2 mL and needs to be repeated, the sample will be cancelled with the comment "TNP-Initial testing necessitated a repeat, but there was insufficient sample to perform repeat".

Specimen:
2 mL serum
Minimum Volume: 1.2 mL

Room temperature.

Room temperature:: 21 days; Refrigerated: 21 days; Frozen: 21 days

Gross hemolysis, Lipemia, Heparinized or EDTA plasma. Icteric, Serum not separated from serum separator tube (SST) gel or clot.

Sunday - Saturday

2-3 days

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.

QuestAssureD 25-Hydroxyvitamin D (D2, D3):
 
Vitamin D, 25-OH, Total 30-100 ng/mL 
25-OHD3 indicates both endogenous production and supplementation. 25-OHD2 is an indicator of exogenous sources, such as diet or supplementation. Therapy is based on measurement of Total 25-OHD, with levels <20 ng/mL indicative of Vitamin D deficiency, while levels between 20 ng/mL and 30 ng/mL suggest insufficiency. Optimal levels are ≥30 ng/mL.

Vitamin D, 25-OH, D3 Not established 
Vitamin D, 25-OH, D2 Not established 

Vitamin D, 1,25-Dihydroxy:

Vitamin D, 1,25 (OH)2, Total   
  1-9 Years       31-87 pg/mL 
  10-13 Years   30-83 pg/mL 
  14-17 Years    19-83 pg/mL 
   Adult              18-72 pg/mL 
Vitamin D3, 1,25 (OH)2 Not established
Vitamin D2, 1,25 (OH)2 Not established 
Reference ranges are established for total 1,25-dihydroxy vitamin D. Values for subcomponents D2 (derived from plant or fungal sources) and D3 (derived from human or animal sources) are provided for informational purposes only.

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.