Sarcoidosis-related hypercalcaemia due to production of parathyroid hormone-related peptide

Hypercalcaemia is frequently observed in patients with sarcoidosis. This is classically attributed to ectopic production of 1,25 dihydroxy vitamin D by sarcoid granulomas. We present a case of sarcoidosis-related hypercalcaemia with normal vitamin D levels. In this patient, production of parathyroid hormone-related peptide (PTHrp) was the cause for sarcoidosis-induced hypercalcaemia. As such, plasma PTHrp levels were increased and bone marrow granulomas stained positively for PTHrp expression. Medium-dose prednisolone treatment improved symptoms of sarcoidosis and normalised serum calcium, and PTHrp concentrations. Thus, production of PTHrp may be the cause for hypercalcaemia in some patients with sarcoidosis.