Routine renal function testing commonly measures which biomarker?

• A. Serum creatinine
• B. Blood urea nitrogen
• C. Uric acid
• D. Albumin

Answer: (A)

Renal function is best assessed by how well the kidneys filter waste from the blood, which is reflected by glomerular filtration rate. Serum creatinine is a waste product produced at a relatively constant rate by muscle and is filtered by the kidneys with minimal reabsorption. As GFR falls, creatinine accumulates in the blood, making serum creatinine a reliable indicator of kidney function. Clinically, it’s routinely measured and used to estimate GFR with formulas, guiding assessment of kidney health and drug dosing.

Blood urea nitrogen can rise for reasons other than reduced filtration, such as dehydration, high protein intake, or liver function, so it’s less specific for GFR. Uric acid is more about gout and stone risk, not general kidney function. Albumin relates to nutritional status and specific kidney diseases like nephrotic syndrome, rather than overall filtration capacity. Therefore, serum creatinine is the most appropriate default biomarker for routine renal function testing.