TURP syndrome is primarily caused by what electrolyte disturbance and mechanism?

• A. Hyperkalemia due to tissue injury
• B. Hypocalcemia due to citrate
• C. Hyponatremia due to absorption of irrigation fluid during TURP
• D. Hypernatremia due to irrigation fluid

Answer: (C)

During TURP, irrigation fluid flushes the surgical field. If this fluid is absorbed into the bloodstream, it dilutes the serum sodium and lowers plasma osmolality. This dilutional hyponatremia causes water to move into brain cells, leading to cerebral edema and neurologic symptoms such as confusion, headache, dizziness, seizures, and even coma. Fluid overload from this absorption can also cause pulmonary edema and hypertension, all together known as TURP syndrome. Modern practice often uses isotonic saline with bipolar resection to reduce this risk, but the fundamental mechanism remains hyponatremia from absorbed hypotonic irrigation fluid. The other options don’t fit because they describe electrolyte disturbances not typical of TURP irrigation absorption (hyperkalemia from tissue injury, citrate-related hypocalcemia, or hypernatremia from irrigation fluids).