Educational information only. At Precursor, blood testing is requested and reviewed by a clinician and considered alongside your history and other markers, not as a stand-alone diagnosis. Testing is performed in NATA-accredited laboratories to ISO 15189 standards.

What is cystatin C?

Cystatin C is a small protein produced by nearly all cells at a fairly constant rate and cleared by the kidneys. Because its production does not depend on muscle mass in the way creatinine does, it offers an alternative and sometimes more accurate way to estimate kidney filtration.

Why it matters

Cystatin C is especially useful where creatinine can mislead, such as in people with unusually high or low muscle mass, or where an early or borderline change in kidney function needs confirming. It is increasingly used to refine an estimate of filtration alongside creatinine-based eGFR.

What your results can mean

Higher than optimal

A raised cystatin C suggests reduced kidney filtration and can sometimes flag a change earlier than creatinine. It is interpreted alongside your other kidney markers.

Within the healthy range

A cystatin C in range supports a picture of healthy kidney filtration, particularly reassuring when it agrees with a normal creatinine-based eGFR.

Reference ranges in Australia

Cystatin C is reported in milligrams per litre (mg/L), with laboratory-specific reference ranges, and can be used to calculate an alternative eGFR. Read your result against the range on your own report and in context.

Test your kidney health with Precursor

Cystatin C adds precision to kidney assessment. At Precursor, kidney testing is requested and reviewed by a clinician within Full Advanced Bloods, a single draw covering your kidney, heart, metabolic, hormonal, liver, thyroid and nutrient markers together, so filtration is read in full context.