What is the most common cause of primary hyperparathyroidism?

What is the most common cause of primary hyperparathyroidism?

• A. A single adenoma in one parathyroid gland
• B. Hyperplasia of all parathyroid glands
• C. Parathyroid carcinoma
• D. Secondary hyperparathyroidism due to renal failure

Answer: (A)

Primary hyperparathyroidism is most commonly caused by a solitary parathyroid adenoma in one gland, which autonomously secretes excess parathyroid hormone. This single benign tumor accounts for the vast majority of cases, driving elevated calcium levels regardless of feedback. The next most frequent cause is hyperplasia of all parathyroid glands, where multiple glands enlarge and secrete more PTH, but this is less common. Parathyroid carcinoma is rare. Secondary hyperparathyroidism due to renal failure is a different scenario where PTH rises in response to chronic hypocalcemia and phosphate retention from kidney disease, not from a primary glandaly lesion.

Primary hyperparathyroidism is most commonly caused by a solitary parathyroid adenoma in one gland, which autonomously secretes excess parathyroid hormone. This single benign tumor accounts for the vast majority of cases, driving elevated calcium levels regardless of feedback. The next most frequent cause is hyperplasia of all parathyroid glands, where multiple glands enlarge and secrete more PTH, but this is less common. Parathyroid carcinoma is rare. Secondary hyperparathyroidism due to renal failure is a different scenario where PTH rises in response to chronic hypocalcemia and phosphate retention from kidney disease, not from a primary glandaly lesion.