Abstract
BACKGROUND AND OBJECTIVES: The correction of vitamin D deficiency is crucial for optimal skeletal and non-skeletal health. Most regimens in current use are based on daily dosing, which may raise concerns of dosage inadequacy and suboptimal patient compliance. Vitamin D is available in 2 forms: D2 (ergocalciferol) and D3 (cholecalciferol). It has been reported that D2 supplements are less effective and may enhance the degradation of 25-hydroxyvitamin D3 (25[OH]D3) metabolite. The aim of this study was to compare the effect of 2 high-dose oral vitamin D regimens--a 10-day course of D3 500,000 IU versus a single mega dose of 600,000 IU D2--on serum 25(OH)D levels. DESIGN AND SETTINGS: A prospective cohort study was conducted from September 2010 to February 2011 in an urban university tertiary hospital in Amman, Jordan. PATIENTS AND METHODS: A total of 109 patients aged 18 to 79 years were enrolled with severe vitamin D deficiency. Fifty-one subjects received 600,000 IU D2 orally and 54 subjects received a total dose of 500,000 IU D3 administered orally, as 50,000 IU D3 daily for 10 consecutive days. Baseline and follow-up total serum 25(OH)D, 25(OH)D2, and 25(OH)D3 levels were compared. RESULTS: The mean total 25(OH)D increment from baseline was 10.33 (5.68) ng/mL over a mean of 43.08 (2.81) days for the D2 group. The mean increment in 25(OH)D for the D3 group was 47.03 (23.67) ng/mL over a mean of 36.9 (2.9) days. The difference between the 2 mean increments was highly significant: P=3.15.10-18. The 600,000 IU D2 single mega-dose decreased 25(OH)D3 levels by an average of 4 ng/mL in 37 subjects. CONCLUSION: Overall, the 10-day oral D3 regimen rapidly and effectively normalized 25(OH)D levels. The shortened dosing interval over 10 consecutive days might result in higher compliance.