Causes

Hypercalcaemia is divided into PTH-mediated hypercalcaemia (primary hyperparathyroidism) and non–PTH-mediated hypercalcaemia. Malignancy-associated hypercalcaemia is the commonest cause of hypercalcaemia in hospitalised patients.

Hypercalcemia affects 20-30 % of cancer patients, more common in Breast cancer , Lung cancer and multiple myeloma

Hypercalcaemia in the setting of malignancy usually indicates disseminated disease.

• PTH-mediated hypercalcaemia is related to increased calcium absorption from the intestine
• Non–PTH-mediated hypercalcaemia includes the following:

Hypercalcaemia associated with malignancy

Unlike PTH-mediated hypercalcaemia, the elevation of calcium that results from malignancy generally worsens until therapy is provided. Hypercalcaemia caused by malignancy is the result of increased osteoclastic activity within the bone.

Granulomatous disorders

High levels of calcitriol may be found in patients with sarcoidosis and other granulomatous diseases. In these disorders, the increased level of calcitriol results from production within the macrophages, which constitute a large portion of some granulomas.

Iatrogenic

In some cases, elevation of calcium is a known adverse effect of the patient’s medications. A complete review of current medications for patients presenting with hypercalcaemia is important.

Learning bite

In patients with myeloma, carcinoma of the lung and breast, suspect the possibility of hypercalcaemia. Hypercalcaemia of malignancy usually indicates disseminated disease and a poor prognosis.