Which laboratory tests are commonly used to assess kidney function?

• A. Serum creatinine and BUN
• B. ALT and AST
• C. Sodium and Potassium
• D. Hematocrit and Hemoglobin

Answer: (A)

Kidney function is evaluated by looking at waste products the kidneys normally clear from the blood. Serum creatinine and BUN are the classic tests for this. Creatinine comes from muscle metabolism and is filtered by the kidneys; when filtration declines, serum creatinine rises. BUN (blood urea nitrogen) reflects urea, a waste product of protein breakdown; it also increases when the kidneys aren’t filtering well, though it can be influenced by factors like hydration, protein intake, and liver function. Together, they give a practical sense of how well the kidneys are performing and help estimate the glomerular filtration rate.

The other options aren’t primary tests of kidney function: liver enzymes ALT and AST indicate liver injury; electrolytes like sodium and potassium can reflect kidney balance but aren’t direct measures of filtration; hematocrit and hemoglobin measure red blood cell levels and oxygen-carrying capacity, not kidney function.