Vitamin D, 1,25-Dihydroxy – This test measures the bioactive form of vitamin D. It is used in the differential diagnosis of hypocalcemia and to monitor patients with renal osteodystrophy or chronic renal failure. This test is not suitable for diagnosis of vitamin D deficiency and monitoring supplementation in most patients. The 25-hydroxyvitamin D test is the recommended test for those purposes (N Engl J Med. 2007;357:266-281).
SST, Serum. Volume 1 (0.5) mL. Stability: Ambient – 72 Hours, Refrigerated – 7 Days, Frozen – 2 Months