Which laboratory test is primarily used to assess kidney function?

The serum creatinine test is primarily used to assess kidney function because it specifically evaluates the level of creatinine in the blood, which is a waste product produced from muscle metabolism. The kidneys filter creatinine out of the blood, and when kidney function declines, the serum creatinine level rises. Clinicians often use serum creatinine levels to estimate the glomerular filtration rate (GFR), an important measure that indicates how well the kidneys are filtering waste from the blood.

In contrast, while the blood urea nitrogen (BUN) test can provide some insight into kidney function, it is influenced by various factors such as hydration status and protein intake, making it less specific than serum creatinine for assessing renal function. Electrolyte panels are useful for evaluating a range of conditions including electrolyte imbalances, but they do not directly measure kidney function. Similarly, a complete blood count (CBC) is valuable for assessing overall health and detecting a variety of disorders, but it does not specifically provide information about kidney function.