Prolonged vitamin D intoxication: presentation, pathogenesis and progress.

Vitamin D toxicity from unactivated vitamin D (calciferol) therapy is currently a rare cause of hypercalcaemia. However, the frequency of this event may increase as high-dose unactivated vitamin D preparations become available. Prolonged vitamin D toxicity can cause reversible hypercalcaemia and partially reversible renal impairment. Parathyroid hormone may not be suppressed with unactivated vitamin D toxicity, especially if renal disease coexists.