Two days after successful parathyroidectomy for a large parathyroid adenoma, a patient develops tetany. Calcium is 6.2 mg/dL, phosphate is 1.8 mg/dL (low), magnesium is normal, and intact PTH is undetectable. Urine output is adequate. What is the most likely explanation?

• A Accidental removal of all four parathyroid glands
• B Acute renal failure reducing calcitriol production
• C Hypomagnesaemia causing functional hypoparathyroidism
• D Hungry bone syndrome from rapid remineralisation of the skeleton ✓

Explanation

Hungry bone syndrome occurs after correction of longstanding severe hyperparathyroidism when the skeleton avidly takes up calcium and phosphate, producing profound hypocalcaemia with HYPOphosphataemia and low PTH. It is commonest with large adenomas and high preoperative alkaline phosphatase. All four glands removed would give hypocalcaemia with HIGH phosphate from loss of phosphaturic PTH action. Magnesium is stated normal, excluding hypomagnesaemic functional hypoparathyroidism, and renal function is preserved.

Reference: Williams Textbook of Endocrinology, 13th ed.

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Written and medically reviewed by the StethoPrep medical team.