What lab test is recommended for a 70-year-old diabetic patient with shingles before initiating antiviral treatment?

The recommended lab test for a 70-year-old diabetic patient with shingles before initiating antiviral treatment is a BUN/Creatinine test. This is important because antivirals used for treating shingles, such as acyclovir, can be nephrotoxic, particularly in patients who may already have compromised kidney function due to age or underlying conditions, such as diabetes.

Evaluating BUN (Blood Urea Nitrogen) and creatinine levels provides insight into the patient's renal function. Since the elderly population and individuals with diabetes are at a higher risk for renal impairment, checking these levels ensures the safe administration of antiviral therapy. If the kidney function is impaired, dosage adjustments may be necessary to avoid potential toxicity.

While other lab tests can provide valuable information, they do not specifically address the potential issue of renal function, which is critical in determining both the safety and efficacy of antiviral treatments in this patient population.