Primary hyperparathyroidism

Primary hyperparathyroidism is an endocrine disorder of calcium metabolism resulting from an abnormal increase in the secretion of PTH from one or more of the parathyroid glands.

Primary hyperparathyroidism is primarily caused by solitary parathyroid adenoma (80%), four-gland hyperplasia (10-15%), multiple adenomas (5%), and parathyroid cancer (< 1%).

The average incidence of primary hyperparathyroidism in men and women in the US is 24.7 and 65.5 cases per 100,000 person-years, respectively. The age-adjusted prevalence in men and women is 85.2 and 232.7 per 100,000 individuals, respectively.

Primary hyperparathyroidism can present with a broad spectrum of clinical manifestations, ranging from asymptomatic biochemical abnormalities to overt end-organ complications. In developed countries, approximately 85% of patients are asymptomatic at diagnosis, identified incidentally through routine biochemical screening, while around 20% present with renal manifestations (such as nephrolithiasis or nephrocalcinosis), skeletal complications (including fractures, osteitis fibrosa cystica, or bone pain), or symptomatic hypercalcemia. In contrast, the majority of patients in developing countries present with symptomatic disease. Symptomatic primary hyperparathyroidism is associated with overt skeletal and renal complications and may also include cardiovascular and neurocognitive symptoms. Asymptomatic primary hyperparathyroidism is further classified based on the presence or absence of target organ involvement, such as reduced bone mineral density or kidney stones. Normocalcemic primary hyperparathyroidism, defined by elevated PTH levels in the setting of normal serum calcium, may also present with or without end-organ involvement.

Parathyroidectomies have > 98% cure rates. The recurrence rates of double parathyroid adenoma, hyperplasia, and single adenoma are 4.0%, 2.2%, and 1.3%, respectively.