Hyperphosphatemia in a crush injury occurs through which mechanism?

• A. Massive cellular lysis or crush injury releasing intracellular phosphate
• B. Inability to excrete phosphate
• C. Increased calcium citrate complexation
• D. Massive transfusion

Answer: (A)

When tissue is crushed, cells rupture and spill their intracellular contents into the bloodstream. Phosphate is largely contained inside cells, so massive cellular lysis releases a large amount of phosphate directly into the serum, producing hyperphosphatemia.

While kidney excretion and other factors can influence phosphate levels later, the immediate and primary mechanism in crush injury is the sudden release of intracellular phosphate from damaged cells.