What lab test is primarily used to assess kidney function?

The serum creatinine level is primarily used to assess kidney function because it provides a specific measure of how well the kidneys are filtering waste from the blood. Creatinine is a waste product generated from muscle metabolism, and under normal circumstances, it is excreted by the kidneys. Therefore, elevated levels of serum creatinine indicate that the kidneys may not be functioning properly, as they are unable to adequately filter out this waste product.

While blood urea nitrogen (BUN) is also a relevant test for assessing kidney function, it is less specific than serum creatinine. BUN can be influenced by other factors, such as protein intake and liver function, making it not as reliable a standalone indicator of kidney health.

The electrolyte panel provides information about the balance of electrolytes in the body, which can be affected by kidney function, but it is not specifically designed to assess kidney filtration ability.

A complete blood count (CBC) measures various components of the blood, such as red and white blood cells and platelets, and does not directly evaluate kidney function. Therefore, while other tests can provide supportive information about kidney health, the serum creatinine level is the main lab test used to assess how well the kidneys are performing their function of waste excretion.