Hypercalcaemia of malignancy

The Endocrine Society guideline (2023) calls hypercalcaemia of malignancy the most common metabolic complication of malignancies and notes that its incidence may be declining with more effective cancer treatment. It recommends (strong recommendation) denosumab or an intravenous bisphosphonate, suggests denosumab over a bisphosphonate, and for severe hypercalcaemia suggests calcitonin with a bisphosphonate or denosumab as initial treatment; treating the cancer itself is described as instrumental to control and prevent recurrence.

The Society for Endocrinology emergency guidance grades severity by calcium adjusted for albumin: below 3.0 mmol/L often without symptoms, 3.0 to 3.5 mmol/L usually needing prompt treatment, and above 3.5 mmol/L needing urgent correction because of the risk of dysrhythmia and coma. High calcium with a low PTH points to malignancy. Reviews describe two main mechanisms, secretion of PTH-related protein by the tumour (humoral hypercalcaemia, about 80% of cases) and bone destruction by osteolytic metastases (about 20%), with calcitriol-mediated cases in lymphoma. Multiple myeloma has the highest prevalence among cancers, breast and renal carcinomas and squamous cell carcinomas of any organ are the commonest solid-tumour causes, and breast cancer and myeloma account for most osteolytic cases.