Vitamin D2 versus vitamin D3 supplementation in hemodialysis patients: a comparative pilot study

Background: In patients with chronic kidney disease, vitamin D insufficiency is highly prevalent. It can be corrected by supplementation with either vitamin D-2 or vitamin D-3. Recent studies in patients without impaired kidney function suggest that vitamin D-3 is more efficient than vitamin D-2 in correcting vitamin D insufficiency. However, no direct comparison has been made in hemodialysis (HD) patients. Methods: Thirty-nine HD patients with serum 25-hydroxyvitamin D (25(OH) D) levels <= 20 ng/mL were enrolled in this comparative, prospective pilot study. They were divided into 3 groups and treated over a 3-month period. Each patient received oral doses of 200,000 international units (IU) vitamin D per month according to the following treatment schedule: (i) vitamin D-2 in small fractionated doses at each HD session, 3 times per week (group D2S); (ii) vitamin D 2 once a month (group D2M); or (iii) vitamin D-3 once a month (group D3M). Changes in serum 25(OH)D levels were measured at the end of the study. Results: Posttreatment serum 25(OH)D levels increased significantly in all groups. The mean +/- SD serum 25(OH)D value for group D3M patients (40 +/- 13 ng/mL) was significantly higher than that for groups D2M (25 +/- 9 ng/mL, p<0.01) and D2S patients (25 +/- 9 ng/mL, p<0.01). Serum 25(OH) D increased to levels >30 ng/mL in 84% of group D3M patients, but in only 15% and 27% of group D2M and D2S subjects, respectively. Conclusion: Vitamin D-3 is more effective than vitamin D-2 in providing adequate 25(OH)D serum levels in HD patients.