Which lab result should a nurse report immediately when a client is taking captopril?

The immediate reporting of potassium levels when a client is taking captopril is crucial due to the medication's potential to cause hyperkalemia. Captopril, an angiotensin-converting enzyme (ACE) inhibitor, is known to interfere with potassium excretion in the kidneys, potentially leading to elevated levels of potassium in the blood. High potassium levels can have serious consequences, including cardiac arrhythmias, which may be life-threatening. Therefore, continuous monitoring of potassium levels is essential for patients on this medication, and any abnormal elevations should be reported right away to ensure prompt management.

While hematocrit levels, sodium levels, and creatinine levels are also important lab values to monitor, they do not carry the same immediate risk of potentially severe complications as elevated potassium levels in the context of captopril therapy. Hematocrit may indicate anemia or hydration status, sodium levels are important for electrolyte balance but not as critical as potassium in this scenario, and creatinine levels provide information about renal function but do not necessitate as urgent a response as potassium abnormalities.