It is the most common cause of hypercalcemia,1,2 with a prevalence of 0.1% to 1.0% and incidence of 28 cases per 100 000.3,4,5 A biochemical diagnosis is made in the setting of elevated calcium and nonsuppressed parathyroid hormone (PTH).1 Classic symptomatic PHP is associated with osteoporosis, fracture, and urolithiasis. The gene discussed is PTH; the disease is hypercalcemia disease.