Hypercalcaemia caused by vitamin D toxicity

Hypercalcaemia can be caused by vitamin D toxicity, usually from an exogenous source (ie calcitriol or high-dose colecalciferol therapy).

If vitamin D toxicity is caused by calcitriol therapy, stop the calcitriol (as well as any concurrent calcium supplement). The hypercalcaemia usually settles within 1 or 2 days.

The formulations of colecalciferol available in Australia are unlikely to cause vitamin D toxicity. However, if toxicity from colecalciferol occurs, stopping treatment might not lead to rapid resolution because colecalciferol is stored extensively in fat. In addition to rehydration, oral glucocorticoids can be effective in severe or protracted vitamin D toxicity. A suitable regimen is:

Continue prednisolone (or prednisone) therapy until the total serum calcium concentration corrected for albumin is within the normal range and hypercalciuria is significantly reduced. Withdraw therapy by tapering the dose to avoid adrenal insufficiency (see Adrenocortical suppression).