Which of the following best describes the pathophysiology of hypocalcemia occurring after thyroid surgery?
- A Increased calcitonin secretion from residual thyroid tissue
- B Dilutional hypocalcemia from intraoperative saline infusion
- C Devascularisation or inadvertent removal of parathyroid glands causing hypoparathyroidism ✓
- D Transient hypomagnesaemia suppressing PTH release
Correct answer: C. Devascularisation or inadvertent removal of parathyroid glands causing hypoparathyroidism
Explanation
Post-thyroidectomy hypocalcaemia is caused by inadvertent removal or devascularisation of the parathyroid glands, leading to transient or permanent hypoparathyroidism. This is the most common metabolic complication of total thyroidectomy, occurring in up to 20% transiently and 1-3% permanently. Calcitonin is not substantially elevated post-thyroidectomy. Dilutional and hypomagnesaemia mechanisms are not primary causes in this surgical context.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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