Final answer:
Hyperkalemia is the complication that would warrant the administration of polystyrene sulfonate (kayexalate) in a patient with acute kidney injury.
Step-by-step explanation:
The complication that would most clearly warrant the administration of polystyrene sulfonate (kayexalate) in a patient with acute kidney injury is hyperkalemia. Hyperkalemia refers to elevated potassium levels in the blood, which can impair the function of the skeletal muscles, nervous system, and the heart. It can be life-threatening, leading to cardiac abnormalities. Kayexalate is a medication that helps remove excess potassium from the body, especially in cases where the kidney is not functioning properly.