Which labs are commonly checked to assess kidney function for dosing decisions?

• A. Liver enzymes (ALT/AST).
• B. Urinalysis alone.
• C. BUN and urinalysis.
• D. Serum creatinine and estimated GFR; BUN may be supplementary.

Answer: (D)

Dosing decisions hinge on how well the kidneys are clearing drugs. Serum creatinine is a waste product that reflects filtration, but by itself it can be misleading because it depends on muscle mass, age, and other factors. Estimated GFR uses creatinine plus age, sex, and sometimes race to estimate true kidney filtering capacity more accurately. Together, serum creatinine and eGFR provide the clearest picture of renal function to guide dosing across different patients. BUN can be affected by factors like protein intake and hydration, so it’s less specific for filtration and not the primary tool for dosing adjustments. Urinalysis shows kidney health in other ways but doesn’t quantify filtration. Liver enzymes aren’t used to gauge kidney function. So the best combination for dosing decisions is serum creatinine and estimated GFR, with BUN as supplementary information when helpful.