Abstract
We report the association of primary hyperparathyroidism (PHPT) and Klinefelter's syndrome (KS) in a 22-year-old male complaining of worsening fatigue. PHPT was asymptomatic at the diagnosis, but the patient had worsening hypercalcemia and osteoporosis, and developed acute renal colic. He then underwent parathyroidectomy with resection of a single adenoma and normalization of calcium and parathyroid hormone levels. Clinical and therapeutic implications of this rare association are discussed. LEARNING POINTS: The coexistence of KS and PHPT is very uncommon.Patients with mild PHPT often have nonspecific symptoms that may be confused and superimposed with those of hypogonadism.KS patients, especially when young and already osteoporotic at diagnosis, should be screened for other causes of secondary osteoporosis, in particular PHPT.