High-Dose Intramuscular Vitamin D Provides Long-Lasting Moderate Increases in Serum 25-Hydroxvitamin D Levels and Shorter-Term Changes in Plasma Calcium

Abstract

The best management of vitamin D deficiency, defined as a 25-hydroxyvitamin D [(25(OH)D] level <50 nM, is unclear. Intramuscular (IM) injection of a large bolus of vitamin D (≥100 000 IU) is used, but its safety is uncertain. In 10 adults given an IM injection of 600 000IU vitamin D₃, we measured at baseline and at 1, 2, 3, and 4 weeks postinjection the serum levels of vitamin D₃, 25(OH)D₃, 25(OH)D₂, total 25(OH)D, 3-epi-25(OH)D₃, and 24,25-dihydroxyvitamin D₃ [24,25(OH)₂D₃] using a standardized LC with tandem MS (MS/MS) assay; serum levels of 25(OH)D using the Abbott ARCHITECT i2000 immunoassay; and markers of bone metabolism. Bone markers and 25(OH)D (immunoassay) were remeasured at 24 weeks. All participants had baseline total 25(OH)D levels >50 nM. Serum 25(OH)D levels increased at 3, 4, and 24 weeks postinjection, peaking at 4 week. Show more