Short and Long-Term Variations in Serum Calciotropic Hormones after a Single Very Large Dose of Ergocalciferol (Vitamin D2) or Cholecalciferol (Vitamin D3) in the Elderly

Context: In humans, few studies have compared the potencies of ergocalciferol and cholecalciferol in improving and maintaining vitamin D status. Objective: Our objective was to evaluate the effects of a single very large dose of both calciferols on serum changes of 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D [1,25(OH)2D], ionized calcium, and parathyroid hormone (PTH) at baseline, and at 3, 7, 30, and 60 d. Design: This was a prospective randomized intervention study. Setting: The study was performed in a nursing home residence. Participants: A total of 32 elderly female patients (age range 66–97 yr), with vitamin D deficiency was included in the study. Intervention: Participants were randomized into four groups of eight to receive a single dose of 300,000 IU ergocalciferol or cholecalciferol by oral (os) or im route. Results: 25(OH)D levels sharply increased at d 3 only when vitamins were given os. The 30-d basal difference in serum 25(OH)D was significantly greater after cholecalciferol os ad...