The most common cause of hypoparathyroidism is which?

• A. Postsurgical removal or damage during neck/thyroid surgery
• B. Autoimmune destruction
• C. Hypomagnesemia
• D. Radiation exposure

Answer: (A)

The key idea is that the parathyroid glands are tiny and sit right near the thyroid; during neck or thyroid surgery they can be accidentally removed or their blood supply damaged. When this happens, parathyroid hormone production drops, leading to hypocalcemia and often hyperphosphatemia. This makes postsurgical injury or removal the most common cause of hypoparathyroidism overall.

Autoimmune destruction can cause hypoparathyroidism, but it’s far less common and often part of broader autoimmune syndromes. Hypomagnesemia can impair PTH release or action and cause a reversible hypoparathyroid state, but it’s not a primary frequent cause in the general population. Radiation exposure to the neck can also damage the glands, but it’s less common than surgical injury.