Which measurement is commonly used to estimate glomerular filtration rate (GFR) in clinical practice?

Which measurement is commonly used to estimate glomerular filtration rate (GFR) in clinical practice?

• A. Serum creatinine concentration
• B. Urine creatinine concentration
• C. BUN
• D. Creatinine clearance

Answer: (A)

Measuring GFR in routine clinical practice relies on serum creatinine concentration because creatinine is produced at a relatively steady rate and is filtered by the glomerulus with minimal reabsorption. The serum creatinine level is used in eGFR equations (like CKD-EPI or MDRD) that adjust for age, sex, and sometimes race to estimate GFR. This approach is practical, widely validated, and easy to perform with a single blood test. Urine creatinine concentration by itself doesn’t measure GFR; it’s used with a timed urine collection to calculate creatinine clearance, which tends to overestimate GFR because of tubular secretion of creatinine. BUN is influenced by hydration and protein intake and doesn’t track GFR as reliably. Creatinine clearance provides a more direct estimate but requires accurate urine collection and is more cumbersome, making it less favored for routine estimation.

Measuring GFR in routine clinical practice relies on serum creatinine concentration because creatinine is produced at a relatively steady rate and is filtered by the glomerulus with minimal reabsorption. The serum creatinine level is used in eGFR equations (like CKD-EPI or MDRD) that adjust for age, sex, and sometimes race to estimate GFR. This approach is practical, widely validated, and easy to perform with a single blood test.

Urine creatinine concentration by itself doesn’t measure GFR; it’s used with a timed urine collection to calculate creatinine clearance, which tends to overestimate GFR because of tubular secretion of creatinine. BUN is influenced by hydration and protein intake and doesn’t track GFR as reliably. Creatinine clearance provides a more direct estimate but requires accurate urine collection and is more cumbersome, making it less favored for routine estimation.