Before administering 80 mg of gentamicin intravenously to a client diagnosed with bacterial pneumonia, which laboratory test should the nurse prioritize?

When administering gentamicin, a type of aminoglycoside antibiotic, it is crucial to monitor renal function because this medication is primarily eliminated by the kidneys. An elevated serum creatinine level can indicate renal impairment, which increases the risk of gentamicin toxicity.

By prioritizing a serum creatinine test, the nurse ensures that the patient's kidney function is adequate to handle the medication. Gentamicin can cause nephrotoxicity, so confirming that the kidneys can effectively process the drug is essential for both the safety and effectiveness of the treatment.

While the complete blood count, liver function tests, and BUN levels also provide important information about a patient's overall health and organ function, serum creatinine directly assesses renal health, which is particularly critical when administering gentamicin.