Aim: To compare the efficacy, tolerability and safety of high doses of i.m. vitamin D2 (ergocalciferol) with oral vitamin D3 (colecalciferol) supplementation in women with low vitamin-D levels.
Design and settings: Of 107 patients (s25(OH)D≤50 nmol/l), aged 2189 years were recruited in a retrospective audit. Participants were separated in two groups according to serum vitamin D levels. The Group 1 included individuals with serum vitamin D levels 3050 nmol/l and the Group 2 with more severe depletion (<30 nmol/l). All Group 1 patients (n=65) were treated with three-doses regimen of oral monthly colecalciferol 40.000 IU (n=33) or ergocalciferol 300.000 IU bolus injection regimen (n=32). The Group 2 (n=42) received 300.000 IU oral colecalciferol (n=21) or 300.000 IU i.m. ergocalciferol (n=21). The primary end points were the serum levels in 25(OH)Vit D at 3 and 6 months for the Group 1 and at 6 weeks, 3 months and 6 months for Group 2.
Results: Oral colecalciferol regimen showed significantly greater levels of 25(OH)vit D from i.m. ergocalciferol treatment at 6 weeks, 3 and 6 months in both groups (Group 1 P<0.008, P<0.05; Group 2 P<0.0001, P<0.001 and P<0.05). The mean difference of 25(OH)vit D concentrations from baseline was significantly greater for oral colecalciferol treatment at 6 weeks and 3 months in both groups. Less than 5% of patients on i.m. ergocalciferol treatment achieved levels >50 nmol/l at 6 weeks, 3 and 6 months, whereas in oral treatment, 100 and 75% of individuals obtained >50 nmol/l at 6 weeks and 3 months, respectively.
All patients in the oral colecalciferol regimen with secondary hyperparathyroidism at baseline (45%, n=23) normalized their PTH levels at 3 months, whereas only 49% (41%, n=22) was corrected at 3 months, in the injection ergocalciferol regimen.
No case of hypercalcemia, vitamin D toxicity, hypercalciuria or nephrolithiasis were observed.
Conclusion: The high dose-bolus oral colecalciferol treatment seems more potent than i.m. injection ergocalciferol regimen at least in the treatment of low vitamin D due to nutritional or environmental factors. The bolus 300.000 IU and the monthly 40.000 IU of oral colecalciferol produced higher and sustained increase in serum 25(OH)vit D.