Vitamin D deficiency is a global problem and vitamin D supplements are used to enhance vitamin D status. There is, however, no agreement on the appropriate dosage and replacement schedule. Current guidelines often recommend doses of 800 IU to 1,000 IU of vitamin D per day in patients at risk for vitamin D deficiency, but in some situations, rapid correction with higher daily doses or single or intermittent dosing schedules are needed. The administration of vitamin D several-fold higher than the current recommended intake was previously suggested, based on its efficacy in correcting rapidly insufficient serum levels of 25(OH)D and its relative safety. Recent clinical trials have, however, shown that very high intermittent dosing schedules have resulted in unfavorable health outcomes.The purpose of this article is to review the mechanism associated with the toxicities of very high intermittent dosing schedules, and to address the proper correction of vitamin D deficiency.
Key points• Doses of 800 IU to 1,000 IU of vitamin D per day are recommended in patients at risk for vitamin D deficiency • Rapid correction schemes for vitamin D deficiency have included high daily doses; as well as single or intermittent megadose boluses administered at variable time intervals• Vitamin D in high daily doses or intermittent megadose boluses can be chosen for a few weeks until adequate 25(OH)D levels are reached. In the case of intermittent administration, it is recommended that individual doses do not exceed 50,000 IU weekly• Very high intermittent vitamin D megadose boluses can cause adverse events and must be avoided