Which lab value is most indicative of kidney function?

The most indicative lab value of kidney function is creatinine. Creatinine is a waste product that is generated from muscle metabolism and is typically produced at a relatively steady rate. It is primarily cleared from the blood by the kidneys; thus, measuring serum creatinine levels provides important insights into kidney function. Elevated levels indicate that the kidneys are not filtering waste products efficiently, which may be a sign of impaired renal function.

In contrast, while blood urea nitrogen (BUN) is also used to assess kidney function, it can be influenced by factors such as hydration status, protein intake, and liver function, making it less specific to kidney impairment compared to creatinine. Electrolyte levels can reflect kidney function to some extent, but they are more indicators of metabolic processes and imbalances than direct measures of renal function. A complete blood count (CBC) primarily assesses overall health and detects a variety of disorders, such as anemia and infections, without providing specific information about kidney performance.