Sporadic primary hyperparathyroidism is one of the causes of hypercalcemia in pediatric ages. A very uncommon condition, it is even less frequent when caused by parathyroid hyperplasia. A presentation is provided of the case of an adolescent with a history of renal lithiasis, hypercalcemia associated to high parathyroid hormone values, and imaging suggestive of lower left parathyroid adenoma by gammagraphy with sestamibi marked with technetium-99m. Surgical exeresis of the affected gland was performed. Anatomopathological examination of the piece revealed the presence of parathyroid hyperplasia. This case presentation contributes to the recognition of primary hyperparathyroidism as one of the diagnostic possibilities when evaluating a pediatric patient with hypercalcemia(AU)