Prescription ergocalciferol dosing for vitamin D repletion: a retrospective evaluation

To determine the efficacy and safety of vitamin D repletion with prescription ergocalciferol and to determine patient-specific factors that may influence the amount of ergocalciferol needed to attain vitamin D sufficiency.

Retrospective medical record review.

University-affiliated outpatient health system.

A total of 1446 patients aged 18-89 years who had a prescription for ergocalciferol 50,000 IU between January 1, 2007, and December 31, 2008, were identified; of these patients, 582 patients had a vitamin D concentration measured 120 days before their first prescription (baseline) and had another concentration measured 60-180 days after this prescription (follow-up) and were deemed "first-time users" of ergocalciferol.

Vitamin D sufficiency was defined as a 25-hydroxyvitamin D (vitamin D) concentration of 30 ng/ml or higher. Twenty-nine different ergocalciferol prescribing regimens were identified in the 1446 patients. For the 582 first-time users of ergocalciferol, vitamin D concentrations increased from a mean ± SE of 17.7 ± 0.32 ng/ml at baseline to 32.9 ± 0.73 ng/ml at first follow-up concentration, with a mean ± SE prescribed ergocalciferol dose of 63,876 ± 1973 IU given over an average of 17 weeks. Overall, 326 (56%) of the 582 first-time users attained sufficiency with their prescribed regimen. With use of a logistic regression model to control for variables that could influence a patient's response to vitamin D, patients prescribed 50,000-100,000 IU/week were significantly more likely to attain vitamin D sufficiency compared with those prescribed less than 50,000 IU/week (OR 2.61, 95% CI 1.37-4.99). Body mass index of 30 kg/m(2) or higher decreased the odds of attaining vitamin D sufficiency, whereas use of a loading dose did not increase the odds of attaining sufficiency.

Many different ergocalciferol regimens were used to replace vitamin D, and overall attainment of vitamin D sufficiency appeared to be moderate. Based on our findings, an ergocalciferol regimen of 50,000-100,000 IU/week with no loading dose could be considered as a starting point for vitamin D repletion.