What abnormal laboratory value should a nurse prioritize for a client taking captopril?

The focus should be on the serum potassium level when a client is taking captopril. Captopril is an angiotensin-converting enzyme (ACE) inhibitor, which can lead to hyperkalemia (increased potassium levels) due to its mechanism of action that affects renal function and the regulation of electrolytes.

In this case, a serum potassium level of 5.2 mEq/L is concerning as it is above the typical upper limit of normal (generally around 5.0 mEq/L). Elevated potassium levels can lead to serious cardiac complications, such as arrhythmias, which are critical to monitor in clients receiving medications like captopril. Given the potential for adverse effects associated with hyperkalemia, this laboratory value should be prioritized for immediate assessment and intervention.

Other values listed, such as serum creatinine, phosphorus, and blood glucose, while important to monitor, do not present the same immediate risk in the context of captopril treatment as elevated potassium does. Serum creatinine of 1.3 mg/dL could indicate some renal impairment but is not an emergency. Serum phosphorus at 4.6 mg/dL is within normal limits for most adults. Lastly, a blood glucose level of 135 mg