Cystatin C

Benefits of the Randox Cystatin C Assay

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Exceptional Correlation

A correlation coefficient of r=1.00 was displayed when the Randox methodology was compared against commercially available methods.

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Excellent Precision

The Randox Cystatin C assay displayed a within run precision of < 4.2%.

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Wide Measuring Range

The Randox Cystatin C assay has a measuring range 0.4 – 10mg/l for the comfortable detection of clinically important results.

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Dedicated Cystatin C Calibrator and Controls

Dedicated Cystatin C Calibrator and Controls available offering a complete testing package.

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Applications Available

Applications available detailing instrument-specific settings for the convenient use of the Randox cystatin C assay on a variety of clinical chemistry analysers.

Ordering information

Cat No	Size
CYS4004	R1 2 x 17.6ml (L) R2 2 x 6.1ml	Enquire Kit Inserts Requests View MSDS Buy Online

(L) Indicates liquid reagent

Instrument Specific Applications (ISA’s) are available for a wide range of biochemistry analysers. Contact us to enquire about your specific analyser.

Traditional CKD Biomarkers

Serum creatinine (SCr) is the most commonly utilised screening test for renal impairment; however, SCr can be affected by age, dietary protein intake, ethnicity, gender, and lean muscle mass. Consequently, the sensitivity of SCr for the early detection of kidney disease is poor and not suitable for the renal assessment in the elderly ¹.

The biggest drawback of SCr is that up to 50% of renal function can be lost before significant SCr levels become detectable as SCr is insensitive to small changes in GFR. Consequently, treatment is not provided at the appropriate time which can be fatal, and so an earlier and more sensitive biomarker for renal function is imperative ².

Physiological significance

Cystatin C (CysC) is a low-molecular-weight (13.3kDa) non-glycosylated protein belonging to the cystatin protease inhibitor family 2, 3. Formed at a constant rate by all nucleated cells, CysC is freely filtered by the glomerular membrane in the kidneys, reabsorbed and fully catabolised by the proximal renal tubule and is not returned to the bloodstream, and so is the ideal marker of glomerular filtration rate (GFR) ^{3, 4}.

Clinical Significance

Serum CysC levels are inversely correlated with GFR ³. The main advantage of CysC as a marker of renal function is in the creatinine 'blind' area, the elderly and in paediatrics ⁵. It has been reported that CysC has important associations with mortality across the GFR range, including those who are grouped as 'preclinical kidney disease' (GFR between 60 and 90mL/min per 1.73m2). Moreover, CysC has been identified as a stronger predictor of adverse cardiovascular outcomes compared to SCr. Combining SCr, CysC and urine albumin to SCr ratio improves risk stratification for kidney disease progression and mortality ⁶.

Covid-19

Acute kidney injury (AKI) presents with elevated levels of CysC in those with severe COVID-19 in comparison to those with mild COVID-19. CysC can be utilised to determine the extent of kidney damage as well as distinguishing those with severe and mild COVID-19 ⁷.