The lack of vitamin D toxicity with megadose of daily ergocalciferol (D2) therapy: a case report and literature review.

The maximum daily dose of vitamin D currently recommended is 2000 IU. Ergocalciferol (D2) 50,000 IU orally weekly for 8-12 weeks is often used to treat vitamin D deficient patients (25(OH) vitamin D <20 ng/mL). The lack of vitamin D toxicity after massive doses of ergocalciferol has yet to be reported in the literature. We report a case of a 56-year-old woman who received supratherapeutic doses of ergocalciferol (150,000 IU orally daily) for 28 years without toxicity. We discuss the possible mechanisms which may account for a lack of toxicity despite intake of massive daily doses of ergocalciferol in this patient.