Which condition leads to hyperphosphatemia due to massive cellular lysis that releases intracellular phosphate?

• A. Chemotherapy
• B. Renal failure
• C. Increased calcium citrate complexation
• D. Crush injury releasing phosphate

Answer: (A)

Massive cellular lysis dumps intracellular phosphate into the bloodstream. In cancer therapy, especially after starting cytotoxic chemotherapy,大量 tumor cells die at once (tumor lysis syndrome), releasing phosphate (along with potassium and uric acid) into the blood. This sudden influx can overwhelm renal excretion, leading to marked hyperphosphatemia. The elevated phosphate also binds calcium, often causing hypocalcemia, and can contribute to kidney injury from calcium phosphate precipitation and uric acid nephropathy. While tissue injury like crush injuries can also release phosphate, the classic and most exam-favored scenario is tumor lysis after chemotherapy, where rapid cell breakdown drives the hyperphosphatemia.