What laboratory value is most indicative of kidney function?

The serum creatinine level is the most indicative measure of kidney function. Creatinine is a waste product formed from the normal metabolism of muscle tissue. The kidneys are primarily responsible for clearing creatinine from the bloodstream; thus, its level in serum reflects how well the kidneys are functioning. When kidney function declines, serum creatinine levels rise, making it a reliable marker for assessing glomerular filtration rate (GFR) and overall renal function.

In contrast, while blood urea nitrogen (BUN) can also indicate kidney function, it is less specific than creatinine. BUN can be influenced by factors such as hydration status, protein intake, and liver function, making it a less reliable standalone measure for renal assessment.

Erythrocyte sedimentation rate (ESR) primarily measures inflammation in the body and does not provide information about kidney function. Similarly, a complete blood count (CBC) is a general test that assesses overall health and can indicate various conditions but does not specifically measure kidney performance.