Introduction and objective: To describe the etiopathogenesis and differential diagnosis between primary hyperparathyroidism and other causes of hypercalcemia. Synthesis: Primary hyperparathyroidism (PHPT) is a common endocrine disease, which is conventionally defined as the existence of hypercalcemia in the presence of elevated levels of parathyroid hormone (PTH). Although the most common form of presentation nowadays is as asymptomatic hypercalcemia, the high morbidity associated with this pathology requires that an early and precise diagnosis be made, both of the etiology and its complications, in order to carry out an adequate management of the affected patients.