A nurse is caring for an older adult client who has a new prescription for spironolactone. Which of the following laboratory values should the nurse monitor for this client?

Rationale: A. Hemoglobin is important for evaluating oxygen-carrying capacity and detecting anemia, but spironolactone does not directly affect hemoglobin levels. This value is not a priority for monitoring the effects of spironolactone. B. Cholesterol levels are relevant for assessing cardiovascular risk, but spironolactone does not significantly impact lipid profiles. Therefore, total cholesterol is not the most important lab to monitor for this medication. C. TSH is used to evaluate thyroid function. Spironolactone does not influence thyroid hormones or TSH levels, so this value is unrelated to the medication’s expected effects or complications. D. Spironolactone is a potassium-sparing diuretic. It works by antagonizing aldosterone in the distal tubule, leading to retention of potassium. This can result in hyperkalemia, especially in older adults or those with renal impairment. Monitoring serum potassium is essential to prevent life-threatening arrhythmias and other complications.