Hungry bone syndrome after parathyroidectomy leads to which electrolyte disturbance?

• A. Hypophosphatemia
• B. Hyperkalemia
• C. Hypermagnesemia
• D. Hyperphosphatemia

Answer: (A)

Hungry bone syndrome after parathyroidectomy is a rapid remineralization process where the bone avidly takes up minerals from the blood once excessive PTH is removed. The sudden fall in PTH drives osteoblast-driven uptake of calcium and phosphate into bone, leading to low serum phosphate (hypophosphatemia) along with often low calcium. This bone-first mineral deposition explains the electrolyte pattern most characteristic of this syndrome.

Hyperkalemia, hypermagnesemia, and hyperphosphatemia don’t fit this mechanism. Potassium and magnesium disturbances aren’t the primary feature, and phosphate levels drop because phosphate is being moved into bone rather than accumulating in the serum.