PATHOGENESIS

Primary hyperparathyroidism (PHPT) is a disease characterized by hypercalcemia attributable to auton-omous overproduction of parathyroid hormone (PTH). Although some patients with PHPT may have normal serum calcium concentrations, most have hypercalcemia. Therefore, PHPT can often be detected by routine serum calcium measurement. PHPT is present in about 1 % of the adult population. The incidence of the disease increases to 2 % or higher after age 55 years and is 2 to 3 times more common in women than in men. PHPT is caused by a single parathyroid adenoma in about 80 to 85 % of cases. The rest of the cases of PHPT can be ascribed to multiple gland hyperplasia affecting all parathyroid glands in about 10%, double adenomas in 4%, and parathyroid carcinoma in 1%. The cause of PHP