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

Test Code

16761

CPT Codes
82306, 82652

Includes

QuestAssureD™ 25-Hydroxyvitamin D (D₂, D₃) and Calcitriol 1,25-Dihydroxyvitamin D

Preferred Specimen

2 mL serum

Patient Preparation
Fasting preferred, but not required

Minimum Volume

1.2 mL

Instructions

Collect blood in a red-top tube (no gel). Allow blood to clot (30 minutes) at room temperature. Centrifuge and separate the serum from the cells.

Transport Container

Transport tube

Transport Temperature

Room temperature

Specimen Stability

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

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Gross hemolysis • Lipemia • Heparinized or EDTA plasma • Icteric • Serum not separated from serum separator tube (SST) gel or clot within 48 hours

Methodology
Chromatography/Mass Spectrometry

FDA Status
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.

Setup Schedule

Set up: Daily; Report available: 2-3 days

Reference Range

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

Calcitriol 1,25-Dihydroxyvitamin D

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 available
Vitamin D₂, 1,25 (OH)2	Not available

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.

Clinical Significance

Vitamin D originating from dietary and endogenous sources is converted to 25-hydroxyvitamin D in the liver, and subsequently to 1, 25-dihydroxyvitamin D in the kidney. Measurement of both the 1, 25-Dihydroxy and 25-Hydroxy forms provide insights into a variety of medical conditions such Vitamin D status in renal failure, differential diagnosis of primary, secondary and tertiary hyperparathyroidism. Differential diagnosis of hypercalcemia and type I and II inherited rickets.

Performing Laboratory
Quest Diagnostics Nichols Institute
33608 Ortega Highway
San Juan Capistrano, CA 92675-2042

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.