SummaryCalcium determination in the blood is necessary in all patients with dehydration and mental confusion of undetermined origin. The first therapeutic measure of severe hypercalcemia will be rehydration. Sodium sulfate or sodium chloride perfusion appears the simplest and most efficient treatment. In the presence of cardiac failure or of serious hypertension sodium EDTA will be indicated. In case of failure of saline perfusions, it is indicated to resort to phosphate administration.Calcitonin must be associated with one of the preceding treatments if hypercalcemia is due to increased osteolysis.