Which lab value is most commonly used to assess kidney function? (often with another marker)

Which lab value is most commonly used to assess kidney function? (often with another marker)

• A. Glucose
• B. Sodium
• C. Creatinine (often with BUN)
• D. C-reactive protein

Answer: (C)

Creatinine is produced at a relatively constant rate and cleared mainly by the kidneys through filtration, so serum creatinine levels closely reflect how well the kidneys are filtering. Clinically, creatinine is used to estimate the glomerular filtration rate (GFR), often alongside BUN, because this pair provides a practical view of kidney function and can help identify when filtration is impaired. The other values listed don’t directly measure filtration: glucose isn’t a kidney filter marker, sodium reflects electrolyte balance, and C-reactive protein indicates inflammation.

Creatinine is produced at a relatively constant rate and cleared mainly by the kidneys through filtration, so serum creatinine levels closely reflect how well the kidneys are filtering. Clinically, creatinine is used to estimate the glomerular filtration rate (GFR), often alongside BUN, because this pair provides a practical view of kidney function and can help identify when filtration is impaired. The other values listed don’t directly measure filtration: glucose isn’t a kidney filter marker, sodium reflects electrolyte balance, and C-reactive protein indicates inflammation.