Which of the following findings indicates potential adverse effects of spironolactone?

The correct answer is that tall T waves indicate potential adverse effects of spironolactone. This medication is a potassium-sparing diuretic, meaning it helps the body retain potassium while promoting the excretion of sodium and water. Spironolactone can lead to hyperkalemia, which is an elevated level of potassium in the blood. One of the classic electrocardiogram (ECG) changes associated with hyperkalemia is the appearance of tall, peaked T waves. This finding is crucial because it signals a potentially dangerous electrolyte imbalance that could lead to life-threatening cardiac arrhythmias.

In contrast, other choices do not specifically align with the adverse effects linked to spironolactone. An increased heart rate may occur due to various reasons, including but not limited to dehydration or anxiety, but it does not reflect a direct adverse effect of the medication. Low blood pressure can result from excessive diuresis but is not as specifically indicative of spironolactone's common side effects. Hypokalemia, or low potassium levels, is generally not associated with spironolactone; rather, the opposite—hyperkalemia—is a key concern. Thus, recognizing tall T waves on an ECG as an indicator of potential adverse