Two days after successful parathyroidectomy for severe primary hyperparathyroidism, a patient develops symptomatic hypocalcaemia with serum calcium 6.8 mg/dL, phosphate 5.9 mg/dL (high), and marked muscle cramps. Preoperative alkaline phosphatase was very high. What explains these findings?

• A Recurrent laryngeal nerve injury causing hypoventilation and respiratory acidosis
• B Vitamin D intoxication from perioperative supplementation
• C Accidental removal of all four parathyroid glands causing surgical hypoparathyroidism
• D Hungry bone syndrome from rapid mineral deposition into previously demineralised skeleton ✓

Explanation

Hungry bone syndrome occurs after parathyroidectomy in patients with severe, long-standing hyperparathyroidism and high bone turnover, indicated by the markedly raised preoperative alkaline phosphatase. Abrupt withdrawal of PTH-driven resorption allows intense osteoblastic uptake of calcium and phosphate, producing hypocalcaemia together with hyperphosphataemia. This phosphate pattern separates it from option C, where hypoparathyroidism causes retention of phosphate but the hallmark here is the avid skeletal uptake in a high-turnover state.

Reference: Williams Textbook of Endocrinology, 14th ed.

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Written and medically reviewed by the StethoPrep medical team.