What is the most common cause of hypoparathyroidism?

• A. Parathyroid gland injury or removal
• B. Autoimmune destruction of parathyroid tissue
• C. Vitamin D deficiency
• D. Magnesium deficiency

Answer: (A)

The main idea is that hypoparathyroidism results from insufficient parathyroid hormone, which is essential for maintaining calcium levels in the blood. The most common way this happens is when the parathyroid glands are damaged or removed during thyroid or other neck surgeries. These tiny glands are close to the thyroid and can be accidentally injured or their blood supply disrupted during procedures, leading to a drop in PTH and a fall in calcium.

Think of PTH as the body’s calcium manager: it increases blood calcium by acting on bone, kidneys, and vitamin D activation. When the parathyroids are impaired, calcium drops and symptoms of hypocalcemia can follow.

Autoimmune destruction of the parathyroid tissue can cause hypoparathyroidism, but it’s much less common than surgical injury. Vitamin D deficiency lowers calcium but does so through a compensatory rise in PTH rather than a lack of PTH itself, so it’s not hypoparathyroidism. Magnesium deficiency can transiently suppress PTH release, but it’s not the primary or most frequent cause in most settings.