Fat Malabsorption (Response to Vitamin D2 Supplement)

Test Code

CPT Codes

Preferred Specimen
1 mL serum

Patient Preparation
A special dietary supplement (50,000 units vitamin D2) is required for fat malabsorption diagnosis.

Minimum Volume
0.2 mL

For fat absorption testing, specimen should be collected at a minimum of 12 hours after ingestion of 50,000 units Vitamin D2 (1 gel capsule).
Allow blood to clot at room temperature. Centrifuge and separate the serum from the cells immediately. Serum collected in a serum separator tube should be removed from the gel within 24 hours.

Transport Container
Plastic screw-cap vial

Transport Temperature
Room temperature

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

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Gross hemolysis • Gross lipemia • Grossly icteric • Heparinized or EDTA plasma • Unseparated serum • Serum in SST® not separated from gel within 24 hours

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 the U.S. Food and Drug Administration. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

Setup Schedule
Set up: Thurs nights; Report available: 7-14 days

Reference Range
Post dose >50 ng/mL

Clinical Significance
Vitamin D (distinct from the vitamin D metabolites, 25-hydroxyvitamin D or 1, 25 dihydroxyvitamin D) is an essential nutrient obtained via exposure to sunlight (cholecalciferol) or diet (ergocalciferol). Measuring the vitamin D cholecalciferol and ergocalciferol can be used in the diagnosis and management of disorders of fat absorption such as Crohn's Disease.

Performing Laboratory
Quest Diagnostics Nichols Inst San Juan Capistrano
33608 Ortega Highway
San Juan Capistrano, CA 92675

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.