Primary hyperparathyroidism is a clinical condition related to an excessive and abnormally regulated secretion of parathyroid hormone (PTH) from the parathyroid glands which is responsible for an alteration of the calcium and phosphorus metabolism. Parathyroid adenomas are the most important cause of primary hyperparathyroidism (80-85%). A case of parathyroid adenoma observed in a patient aged 47, admitted to the Emergency Medicine Department of our Hospital with a diagnosis of hypertensive crisis, cephalea, vomiting, and a clinical history of recurrent episodes of severe abdominal and renal pain, is presented. Lab data showed severe hypercalcemia and a progressive worsening of the renal function. A severe neurological involvement with stupor, derangement of mind, the arising of acute respiratory depression, lethargy compelled the colleagues to transfer him to the Intensive Care Unit; a neck ultrasonography showed a poor-echogenous area under the right thyroid inferior pole, with signs of vascularization. The suspect of a primary hyperparathyroidism related to a single adenoma of the parathyroid gland suggested a surgical treatment. A ''concise parathyroidectomy'' was performed. Our surgical approach was confirmed by the comparison of the preintervention and the post-intervention iPTH values: 2080 pg/mL (normal range: 12-65 pg/mL) before excision vs 101 pg/mL after the removal. The histologycal exam reported a parathyroid adenoma with large areas with haemorrage. Three days after surgery the patient was in good general conditions. Patients affected by primary hyperparathyroidism are often misdiagnosed because their clinical conditions can create differential diagnosis problems with other diseases. However the surgical option remains the gold standard treatment.