Hungry bone syndrome results in which electrolyte change?

• A. Hypocalcemia
• B. Hypercalcemia
• C. Hyperkalemia
• D. Hyperphosphatemia

Answer: (A)

When hungry bone syndrome occurs, the skeleton suddenly pulls minerals from the blood after treatment of severe hyperparathyroidism, so the quickest and most consistent change is a drop in serum calcium. The abrupt drop in PTH or its effects shifts bone activity from resorption to rapid formation, drawing calcium (and phosphate) into bone. Calcium sinks from the bloodstream, leading to hypocalcemia, which can cause symptoms like tingling, cramps, or muscle issues and may affect heart rhythm if severe. Hypercalcemia doesn’t happen in this scenario because the trigger is bone remineralization after parathyroid suppression, not release of calcium from bone. Hyperkalemia isn’t the characteristic change, and while phosphate may be decreased as it’s deposited into bone, the hallmark electrolyte abnormality you’re asked to identify is low calcium. Management focuses on calcium supplementation, often with active vitamin D to improve calcium absorption, and careful monitoring of calcium, phosphate, and magnesium.