Enhanced production of calcitriol, and hypercalcaemia in a patient with sarcoidosis provoked by daily intake of calciol.

A case of sarcoidosis is described which presented with hypercalcaemia and renal insufficiency. Initially, a calciol intoxication was diagnosed, because a high daily intake was suspected. However, vitamin D3 metabolites in the blood revealed normal concentrations of calcidiol, but extremely high concentrations of calcitriol. These features rejected the first diagnosis and pointed to high endogenous calcitriol production, which may take place in granulomatous diseases. This is caused by an increased 1-alpha-hydroxylation reaction in activated macrophages. Eventually, muscle biopsy revealed non-caseating granulomas, confirming the diagnosis of sarcoidosis.