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.

The loss of homeostatic control of PTH synthesis and secretion causes an increase in PTH secretion by either single cell or parathyroid hyperplasia. Normally, there is an inverse sigmoid relationship between calcium concentration and parathyroid secretion; however, in primary hyperparathyroidism, parathyroid cells in adenomas become less sensitive to the inhibitory action of calcium resulting in hypercalcemia. Since the PTH plays an important role in bone homeostasis and calcium reabsorption in kidneys, the disease is characterized by skeletal deformities, pathological fractures, and kidney stones and may also lead to cardiac and neurocognitive manifestations.

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.