Cystatin C is a low-molecular-weight protein produced at a nearly constant rate by all nucleated cells, freely filtered by the kidney's glomeruli and then reabsorbed and catabolized by the tubules, so its blood concentration reflects the glomerular filtration rate (GFR). Unlike serum creatinine, cystatin C is largely independent of muscle mass, diet, age, and sex, so cystatin C-based estimated GFR (eGFRcys), alone or combined with creatinine in the 2021 race-free CKD-EPI equations, can estimate filtration more accurately in many people and flags more chronic kidney disease than creatinine alone (13.7% vs 9.7% below an eGFR of 60 in general-population cohorts). The KDIGO 2024 guideline recommends estimating GFR from both markers together when cystatin C is available, cementing its role as the standard confirmatory measure of kidney function.
Across large cohorts and meta-analyses, cystatin C-based eGFR is at least as accurate as creatinine-based eGFR and is more strongly associated with death, cardiovascular events, and end-stage kidney disease—in one ~90,750-person consortium meta-analysis it markedly improved risk reclassification for death—and it independently predicts mortality in the general population and in heart failure, with particular value in older adults and people with atypical muscle mass. Evidence is not uniform (cystatin C did not outperform creatinine in a sub-Saharan African validation), and levels are themselves influenced by thyroid dysfunction, corticosteroids, obesity, smoking, and inflammation; the test also costs more than creatinine. This evidence describes the cystatin C biomarker and the eGFR equations themselves, not this specific commercial test product.
Peer-reviewed studies on the active compound — citations link to PubMed.
“lower eGFR was associated with increased rates of adverse outcomes”
“Patients with elevated cystatin C have a higher risk of all-cause, cardiovascular, and cancer death”
“The use of cystatin C alone or in combination with creatinine strengthens the association between the eGFR and the risks of death and end-stage renal disease across diverse populations.”
“New eGFR equations that incorporate creatinine and cystatin C but omit race are more accurate and led to smaller differences between Black participants and non-Black participants than new equations without race with either creatinine or cystatin C alone.”
“We show that eGFRcys is most strongly associated with CVD and mortality, and, along with albuminuria, adds predictive discrimination to current CVD risk scores, whilst traditional creatinine-based measures are weakly associated with risk.”
“The cystatin C concentration is an independent risk factor for heart failure in older adults and appears to provide a better measure of risk assessment than the serum creatinine concentration.”
Research describes the active mechanism and is not a claim about this specific product.
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Yes — its active compound is linked to 18 peer-reviewed studies, summarized and cited above.
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