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Vitamin D, 1,25 Dihydroxy

Calcitriol Level

Test Codes

Antrim #32034, EPIC: LAB5844, SOFT: D2OH

Department

Special Chemistry

Instructions

This test should NOT be used as an initial screen for vitamin D deficiency nor to assess vitamin D toxicity. Vitamin D, 25-Hydroxy is the appropriate test for initial assessment of vitamin D stores.

Specimen Collection Criteria

Collect (preferred specimen): One Gold-top SST tube. (Minimum Whole Blood: 4.0 mL)

Physician Office/Draw Specimen Preparation

Let specimen clot 30-60 minutes. Centrifuge SST tube to separate serum from cells. Transfer 1.0 mL serum to a plastic transport tube and refrigerate (2-8°C or 36-46°F). (Minimum Serum: 1.0 mL)

Preparation for Courier Transport

Transport: 1.0 mL serum, refrigerated (2-8°C or 36-46°F). (Minimum Serum: 1.0 mL)

Rejection Criteria

Plasma specimens. 

Severely lipemic, icteric, or grossly hemolyzed specimens. 

In-Lab Processing

Let specimen clot 30-60 minutes. Centrifuge SST tube to separate serum from cells. Transfer 1.0 mL serum to a plastic transport tube and refrigerate (2-8°C or 36-46°F). (Minimum Serum: 1.0 mL)

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 72 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 6 months

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days

Laboratory

Royal Oak Special Testing Laboratory

Performed

Twice a week.
Results available within 7 days.

Reference Range

19.9 – 79.3 pg/mL.

Test Methodology

Chemiluminescence Immunoassay (CLIA).

Interpretation

1,25-Dihydroxy vitamin D is low in chronic kidney disease, hypoparathyroidism and low or normal in cases of vitamin D toxicity. 1,25-Dihydroxy vitamin D may be high in sarcoidosis, other granulomatous diseases, some malignancies and 1° hyperparathyroidism.

Clinical Utility

1,25-Dihydroxy vitamin D is the active form of vitamin D and is produced primarily in the kidney. Its measurement may be useful in the:

• Assessment of vitamin D status in patients with significant kidney disease.
• Differential diagnosis of hypercalcemia when the cause is not clear.
• As part of the workup to evaluate a patient for possible metabolic bone disease.
• Investigation of selected patients with vitamin D deficiency when the cause is unclear and/or inherited disorder is suspected (e.g., end-organ resistance to 1,25-dihydroxy vitamin D.

This test should NOT be used as an initial screen for vitamin D deficiency nor to assess vitamin D toxicity. Vitamin D, 25 Hydroxy is the appropriate test for initial assessment of vitamin D stores.

CPT Codes

82652
LOINC: 1649-3

Contacts

Last Updated

1/12/2023