Cystatin C

Cystatin C is a protein produced by all cells in the body at a steady rate and filtered out by the kidneys. Its levels in the blood help doctors assess kidney function because when the kidneys are working well, cystatin C is easily removed, resulting in lower blood levels. Elevated levels can indicate impaired kidney function or damage. Because cystatin C is less affected by factors like age, muscle mass, or diet compared to other tests, it provides a reliable marker for detecting early kidney problems and monitoring their progression.