What laboratory test is used to evaluate kidney function?

Serum creatinine is a key laboratory test used to evaluate kidney function because it reflects the kidneys' ability to filter waste products from the blood. Creatinine is a byproduct of muscle metabolism and is produced at a fairly constant rate, making it a reliable indicator of kidney filtration efficiency. When the kidneys are functioning properly, they effectively filter out creatinine, thus maintaining its levels within a normal range in the serum.

An increase in serum creatinine levels can indicate a decline in kidney function, making it a crucial parameter for assessing renal health. Clinicians often use serum creatinine values to estimate the glomerular filtration rate (GFR), which provides further insight into the kidneys' filtering capacity and overall function.

While blood urea nitrogen (BUN) and serum electrolytes also provide information about kidney function, they are influenced by factors other than just renal function, such as hydration status and dietary protein intake. The complete blood count (CBC) does not offer specific information regarding kidney function, as it primarily evaluates overall blood health and cellular components.