Final answer:
A nurse should assess the client's renal function before administering the first dose of vancomycin to ensure that the kidneys can handle the medication without damage.
Step-by-step explanation:
Before administering the first dose of vancomycin, a nurse should assess the client's renal function. Vancomycin is a potent antibiotic that can be nephrotoxic, meaning it has the potential to cause kidney damage. Therefore, checking renal function with tests such as serum creatinine levels is crucial to ensure the patient's kidneys are capable of handling the medication without sustaining damage. This assessment helps in determining the correct dosing for vancomycin and in monitoring for potential drug-related nephrotoxicity.