The nurse is monitoring a client taking a potassium sparing diuretic. Which of the following findings would prompt the nurse to notify the health care provider?

The correct answer is C: Serum potassium level of 5.5 mEq/L. With a potassium-sparing diuretic, the medication works by promoting the retention of potassium, leading to the possibility of hyperkalemia (high potassium levels). A serum potassium level of 5.5 mEq/L is above the normal range (3.5-5.0 mEq/L) and can indicate potential toxicity. Hyperkalemia can cause serious cardiac arrhythmias and must be promptly addressed by notifying the healthcare provider for further evaluation and management. Choices A and B are within normal limits and do not directly relate to the effects of a potassium-sparing diuretic. Choice D is below the normal range and would not typically prompt immediate notification unless symptomatic.