Comparative efficacy and safety of different doses of ergocalciferol supplementation in patients with metabolic syndrome
Background Vitamin D deficiency is a common problem worldwide. Several studies have shown an association between vitamin D deficiency and the increased risk of metabolic syndrome. No previous study has compared the efficacy and safety of ergocalciferol at 40,000 versus 20,000 IU/week in patients with metabolic syndrome. Objective To evaluate the efficacy of ergocalciferol supplementation on serum 25-hydroxyvitamin D [25(OH)D] concentrations and to examine safety parameters in metabolic syndrome patients. Setting Outpatient department of Phramongkutklao Hospital, Bangkok, Thailand. Method A randomized, double-blinded, parallel study was conducted in metabolic syndrome patients with vitamin D deficiency [25(OH)D <20 ng/mL]. Ninety patients were randomly assigned into three groups of 30 patients each. Group 1 was given two capsules of placebo/week, group 2 was given ergocalciferol 20,000 IU/week, and group 3 was given ergocalciferol 40,000 IU/week for 8 weeks. Main outcome measure serum 25(OH)D concentrations, serum calcium, safety, and corrected QT (QTc) interval. Results Of the 90 patients enrolled, 84 patients completed the study. At the end of the study, the mean serum 25(OH)D in groups 2 and 3 significantly increased from the baseline (15.1 and 14.3 to 26.8 and 30.0 ng/mL, respectively). The increase in serum 25(OH)D in groups 2 and 3 were comparable and significantly greater than that of the placebo group. The percentage number of patients achieving normal vitamin D levels in groups 1, 2 and 3 were 3.3, 33.3, and 60.0 %, respectively, which were significantly different between groups (p < 0.001). Adverse reactions in both ergocalciferol treatment groups were not different from the placebo group (p > 0.05). Serum calcium levels did not change within and between groups of treatment. No significant change in QTc was observed in any patient. Conclusions Both 20,000 and 40,000 IU/week of ergocalciferol supplementation for 8 weeks were able to increase serum 25(OH)D concentrations significantly. However, more patients in the ergocalciferol 40,000 IU/week treatment group achieved a normal serum 25(OH)D level than in the group which received 20,000 IU/week. Clinicians would have informed of choosing the dosing regimen of ergocalciferol in metabolic syndrome patients.