Which laboratory test is most useful for evaluating renal function?

The most useful laboratory test for evaluating renal function is serum creatinine. Creatinine is a waste product generated from muscle metabolism, and it is primarily cleared from the bloodstream by the kidneys. Therefore, measuring serum creatinine levels provides insight into how well the kidneys are functioning. Elevated serum creatinine indicates impaired kidney function or decreased glomerular filtration rate, which is a key indicator of renal health and function.

In contrast, blood glucose levels primarily assess carbohydrate metabolism and are not specific to kidney function. A complete blood count evaluates various components of the blood, such as red and white blood cells, but does not provide direct information about kidney function. Prothrombin time is a test for assessing blood coagulation and liver function, which also does not relate directly to how well the kidneys are performing their role in waste elimination. Thus, serum creatinine stands out as the most relevant test for renal function assessment.