Of the expected electrolyte derangement with ruptured bladders, which is most concerning for the patient?

• A. Hyperkalemia, greater than 5.5 mEq/L
• B. Hyponatremia
• C. Hypocalcemia
• D. Hyperkalemia less than 5.0 mEq/L

Answer: (A)

When urine leaks from a ruptured bladder into the peritoneal cavity, the peritoneum rapidly absorbs electrolytes from that urine, causing a rise in serum potassium. This hyperkalemia is the most dangerous because it directly disrupts cardiac conduction and can lead to life-threatening arrhythmias. A potassium level above about 5.5 mEq/L is a threshold at which the risk of serious cardiac events becomes prominent, making it the most concerning electrolyte disturbance in this scenario. Hyponatremia and hypocalcemia can occur as well, but they do not pose as immediate a threat to the heart in this context as hyperkalemia.