Which labs are commonly used to assess kidney function?

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

Answer: (A)

Evaluating how well the kidneys are working relies on measuring waste products that build up in the blood when filtration slows. Serum creatinine and blood urea nitrogen are the primary lab measures for this because they directly reflect the kidneys’ ability to filter and excrete waste. Creatinine is a byproduct of muscle metabolism that is normally cleared by filtration; higher levels indicate reduced glomerular filtration. BUN measures nitrogenous waste from protein breakdown and rises when filtration decreases or when factors like dehydration influence the blood. Together (and often used to estimate GFR), these values give a clear picture of kidney function.

ALT and AST are enzymes used to assess liver function, not kidney function. Hematocrit and hemoglobin indicate red blood cell levels and can reveal anemia, which can occur with chronic kidney disease but do not measure filtration capacity themselves. Sodium and potassium are electrolytes whose balance is regulated by the kidneys; abnormalities signal possible dysfunction but are not direct indicators of filtration efficiency. So, the most accurate indicators for assessing kidney function are serum creatinine and BUN.