Effect of Different Dosagse of Intramuscular Vitamin D3 on Serum 25(OH)D

Pareneteral vitamin D3 administration, a common practice in Iran, is usually used based mainly on clinical symptoms or serum mineral disturbances. Since studies about the effects and side effects of parenteral vit D3 preparations are limited, this study was designed to evaluate the effect of different intramuscular vitamin D3 dosage on serum 25(OH)D levels. In this study, 54 health voluneers were selected, and randomly assigned to 4 groups, based on their serum vitamin D3. Mean body mass index, age and sex frequency were not significantly different between groups. Mean serum 25(OH)D levels before injections were 27.24±21.30, 25.21±17.09, 24.70±16.8 and 25.10±14.48 ng/mL in groups I to IV respectively. Vitamin D3 was injected in dosages of 300/000, 600/000, 900/000 units and placebo in groups I-IV respectively. 25(OH)D levels were determined before, and at 2 weeks, 2 months and 4 months after injection. Serum 25(OH)D levels before injection were significatly higher compared to levels assessed 2 and 4 months after injection. At the end of study, in groups I to III, mean serum 25(OH)D levels in group I to IV were 48.20±28.32 ng/mL, 65.46±33.52 ng/mL, 72.90±37.68 ng/mL, and 14.38±11.14 ng/mL respectively. Frequency of vitamin D hypervitaminosis in groups I, II and III was 9%, 38% and 40% respectively. Usage of parenteral vit D3, especially dosages higher than 300/000 IU, is associated with a high risk of vitamin D hypervitaminosis.