Hyperparathyroidism

Hyperparathyroidism is a disorder characterized by excessive secretion of parathyroid hormone (PTH) from the parathyroid glands, leading to elevated calcium levels in the blood. It is categorized into primary, secondary, and tertiary forms, each with distinct causes and clinical implications.

Primary hyperparathyroidism occurs when one or more parathyroid glands produce too much PTH, most commonly due to a solitary parathyroid adenoma, but also due to multiglandular hyperplasia or, rarely, parathyroid carcinoma. The resulting hypercalcemia promotes bone resorption, increased renal calcium reabsorption, and, indirectly, increased intestinal calcium absorption. Many cases are asymptomatic and detected through routine calcium screening; when symptoms occur, they may include bone pain or fractures, kidney stones, fatigue, weakness, polyuria, dehydration, constipation, and neurocognitive complaints.

Secondary hyperparathyroidism arises from chronic hypocalcemia, typically due to chronic kidney disease or severe vitamin D deficiency, which stimulates continuous PTH production and glandular hyperplasia. Tertiary hyperparathyroidism develops after prolonged secondary hyperparathyroidism, when the glands become autonomous and continue to secrete PTH despite correction of calcium levels.

Diagnosis relies on measuring serum calcium and PTH, with imaging such as a sestamibi scan or ultrasound used to localize abnormal glands when surgery is planned. Treatment depends on type and severity. Primary hyperparathyroidism often requires surgical removal of the affected gland(s). Indications include symptomatic hypercalcemia, significant hypercalcemia, kidney impairment, or young age; asymptomatic cases may be monitored. Non-surgical options include hydration, bone-protective therapies, cinacalcet for hypercalcemia, and management of contributing conditions. Secondary and tertiary forms focus on treating the underlying kidney disease and controlling calcium and phosphate balance, with surgery reserved for select cases.