What is a primary indicator of kidney function?

Creatinine levels serve as a primary indicator of kidney function because creatinine is a waste product generated from muscle metabolism. The kidneys are primarily responsible for filtering creatinine out of the blood and excreting it in urine. Therefore, when kidney function is impaired, creatinine levels in the bloodstream rise, reflecting the kidneys' reduced capacity to perform their filtering role.

Monitoring creatinine levels can help healthcare providers assess renal function and can be particularly useful in diagnosing and managing conditions that affect the kidneys. Unlike the other options listed, which may indicate various other health issues or bodily functions, creatinine levels are specifically tied to how well the kidneys are working. This direct relationship makes it a crucial marker in evaluating renal health.