The establishment of an abnormal calcemia first requires confirmation by a second measurement that should then be interpreted in relation to albuminemia. Should the abnormality be confirmed, measurement of intact parathormone in serum can help distinguishing between a parathyroid or non parathyroid source of origin. In presence of plasma calcium level lower than or equal to 2.9 mmol/L regular monitoring should be provided and aggravating factors such as thiazide diuretics, dehydration or high calcium intake, avoided. If plasma calcium is greater than 3 mmol/L the patient should first be rehydrated. In case of primary hyperparathyroidism, parathyroidectomy is the only effective treatment. In neoplastic hypercalcemia bisphosphonates are the first choice treatment when antitumoral therapy turns out to be insufficient. Hypocalcemia can be effectively corrected by calcium and vitamin D derivatives.