QuestAssureD™ 25‑Hydroxy and Calcitriol 1,25‑Dihydroxyvitamin D
Use
This test measures both 25‑hydroxyvitamin D (including D2 and D3 forms) and the metabolically active form calcitriol (1,25‑dihydroxyvitamin D), helping assess vitamin D metabolism comprehensively — particularly useful in disorders affecting vitamin D metabolism, such as chronic kidney disease or hereditary defects in hydroxylation pathways. Measurement of 1,25‑dihydroxyvitamin D is not a reliable indicator of vitamin D reserves but is valuable in evaluating acquired or inherited metabolic disorders. ([questdiagnostics.com](https://www.questdiagnostics.com/healthcare-professionals/about-our-tests/endocrine-disorders/vitamin-d?utm_source=openai))
Special Instructions
Not provided.
Limitations
Serum 1,25‑dihydroxyvitamin D may be normal or even elevated in vitamin D deficiency due to secondary hyperparathyroidism, and does not reflect vitamin D status. Interpretation must consider various disorders such as renal failure, hypoparathyroidism, granulomatous diseases, or genetic mutations in vitamin D metabolism. ([questdiagnostics.com](https://www.questdiagnostics.com/healthcare-professionals/about-our-tests/endocrine-disorders/vitamin-d?utm_source=openai))
Methodology
Mass Spectrometry
Biomarkers
Result Turnaround Time
Not provided.
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
Not provided
Minimum Volume
Not provided