When starting ACE inhibitors in heart failure, which labs should be monitored regularly?

• A. Potassium and Bicarbonate
• B. Sodium and Creatinine
• C. Calcium and Phosphate
• D. Potassium and Creatinine

Answer: (D)

When starting ACE inhibitors in heart failure, the main issue is how the drug affects kidney function and potassium balance. ACE inhibitors reduce angiotensin II, which causes efferent arteriolar dilation and can lower intraglomerular pressure. In heart failure, this can lead to a small rise in creatinine, reflecting a change in kidney filtration. At the same time, blocking aldosterone increases potassium retention, raising the risk of hyperkalemia. Because of these dual effects, it’s essential to check both potassium and creatinine regularly after initiating therapy or adjusting the dose. Baseline values are followed by a check in about 1–2 weeks, and then periodically thereafter, especially if the patient has CKD, dehydration, is taking diuretics, or uses NSAIDs. If creatinine climbs significantly or potassium becomes elevated, treatment may need adjustment. Other labs like bicarbonate, calcium, or phosphate aren’t the primary monitoring targets for this medication’s initiation, making potassium and creatinine the most important pair to track.