Malignant hypercalcemia is the main metabolic complication of cancer. Clinical presentation varies from asymptomatic to a medical emergency. The main causes include parathyroid hormone-related protein production and bone metastases, while hypervitaminosis D and hyperparathyroidism are rarer causes. Diagnosis is based on the demonstration of elevated serum calcium and low PTH in the context of known or suspected cancer. Treatment is aimed at correcting hypovolemia by hydration, reducing bone resorption, and treating the underlying cancer. The aims are to improve patients' quality of life, minimize delays in oncological management and reduce mortality associated with this condition.