Common causes of hypercalcemia

Hyperparathyroidism, including ectopic hyperparathyroidism

Humoral hypercalcemia of malignancy via parathyroid-related protein (especially malignancy of the lung, kidney, ovary, head and neck, and esophagus)

Renal failure

Malignancy via direct bone destruction (especially myeloma, lymphoma and metastatic breast cancer)

Thiazide diuretics

Uncommon causes of hypercalcemia

Immobilization

Lithium use

Vitamin D toxicity

Hyperthyroidism

Milk alkali syndrome

Multiple endocrine adenomatosis syndromes

Granulomatous diseases, especially sarcoidosis, via increased levels of 1,25(OH)2D3

Familial hypocalciuric hypercalcemia