The use of potassium-sparing diuretics is contraindicated in patients with anuria, acute or progressive renal insufficiency, or diabetic nephropathy. Potassium-sparing diuretics can cause hyperkalemia, which may result in life-threatening cardiac arrhythmias. Careful monitoring of serum potassium levels is necessary in all patients treated with potassium-sparing diuretics, especially during initiation of therapy, after dosage adjustment, and during illness that could alter renal function.