Twist on a classic: vitamin D and hypercalcaemia of malignancy

Malignancy is the most common cause of hypercalcaemia in the inpatient setting. Most cases are caused by tumour production of parathyroid hormone-related protein and osseous metastases. In less than 1% of cases, hypercalcaemia is driven by increased production of 1,25-dihydroxyvitamin D (1,25(OH)₂D), a mechanism most commonly seen in haematological malignancies. Here, we describe a woman with metastatic small cell cervical carcinoma who developed hypercalcaemia secondary to paraneoplastic overproduction of 1,25(OH)₂D, a finding that, to our knowledge, has not been previously associated with this cancer. We also review the current cases of solid tumours reported to have this mechanism of hypercalcaemia and the evidence behind multiple therapeutic approaches.