The establishment of an abnormal calcemia first requires confirmation by a second measurement that should then be interpretated in relation to albuminemia. Should the abnormality be confirmed, measurement of intact parathormone in serum can help distinguishing between a parathyroid or nonparathyroid source of origin. In presence of a plasma calcium level lower than or equal to 2.9 mmol/l regular monitoring should be investigated 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 by vitamin-D derivatives.