Hypercalcemia of malignancy

Hypercalcemia of malignancy is a metabolic complication of cancer in which tumours or their secretions push the calcium level in the blood above normal. It is common among people with cancer, and in hospitalised patients cancer is the leading cause of high calcium. Most cases arise when tumours release a protein resembling parathyroid hormone, while bone metastases and lymphomas that raise active vitamin D account for the rest. Lung cancer, breast cancer and multiple myeloma are among the cancers most often linked to it. Features include nausea, constipation, poor appetite, thirst, frequent urination, muscle weakness, bone pain and confusion that can deepen into coma; kidney damage is a recognised complication. Diagnosis rests on blood tests for calcium, parathyroid hormone, the related protein and vitamin D metabolites. Severe cases need urgent hospital treatment with intravenous fluids and bisphosphonates, sometimes with a fast-acting calcium-lowering hormone or steroids, alongside treatment of the underlying cancer.