What should a nurse monitor for a patient taking ACE inhibitors?

Monitoring serum potassium levels is crucial for a patient taking ACE inhibitors due to the medication's effect on the renin-angiotensin-aldosterone system. ACE inhibitors can lead to increased potassium retention in the kidneys because they inhibit the conversion of angiotensin I to angiotensin II, which plays a role in stimulating aldosterone secretion. Aldosterone promotes the excretion of potassium; therefore, its levels may rise when its effects are blocked. Hyperkalemia, or elevated potassium levels, can result in serious cardiac issues, including arrhythmias.

In the context of the other options, while monitoring pulmonary function, liver enzymes, and white blood cell count may be relevant in certain situations or with different medications, they are not the primary focus when a patient is on ACE inhibitors. Pulmonary function is less affected by ACE inhibitors, and issues related to liver enzymes and white blood cell counts are typically associated with other medication classes or specific conditions rather than with ACE inhibitors. Hence, closely monitoring serum potassium levels is key to patient safety when administering these medications.