A nurse is reviewing the lab work of a client on a medical-surgical unit who has a new prescription for captopril. Which of the following laboratory values should the nurse identify as the priority to monitor?

A. Monitoring alanine aminotransferase is important for liver function, but it is not the priority for a client on captopril. B. Thyroid-stimulating hormone is not directly impacted by captopril and is not the priority lab value to monitor in this context. C. Potassium is the priority laboratory value to monitor because captopril, an ACE inhibitor, can lead to hyperkalemia (elevated potassium levels), which can cause serious cardiac complications. D. While magnesium levels are important to monitor, they are not specifically related to captopril therapy as potassium levels are.