FAQ: Which patient populations would benefit from cystatin C testing?
08. Mar 2020 |
4 min read
In this segment we will answer questions our Product Manager for cystatin C and Product Specialist in the US get about cystatin C at exhibitions, conferences and client meetings. Today’s question is "Which patient populations would benefit from supplemental cystatin C testing?"
Which patient populations would benefit from supplemental cystatin C testing?
Patients likely to receive inaccurate assessments of renal function based on creatinine values alone stand to benefit the most from supplemental cystatin C testing.
The main source of imprecision in creatinine-based eGFR is its dependence on muscle mass. For this reason, cystatin C is considered the ideal endogenous marker for GFR in adults, including elderly, and children* whose muscle mass vary considerably . The vulnerability of creatinine to changes in body habitus further indicate that confirmatory cystatin C testing would be warranted in athletes, amputees, military personnel, patients with brain-stem injuries and those with conditions linked to malnutrition.
Guidelines published by KDIGO and NICE suggest that cystatin C could be used to curb over-diagnosis of chronic kidney disease (CKD). According to these guidelines, CKD patients with a creatinine-based eGFR between 45-59 ml/min/1.73 m2 and no proteinuria (ACR less than 3 mg/mmol) would benefit from confirmatory cystatin C testing. The relative advantages of cystatin C as a marker for kidney function also make it suitable for use in situations that are outside the purview of most nephrologists. For instance, one hospital in Germany noted savings in excess of 100,000 € by optimising chemotherapeutic drug doses through co-reporting of creatinine and cystatin C based eGFRs . This finding supports previous assertions that drug-specific dosing protocols based on cystatin C would be beneficial to patients who are prescribed medications that are renally eliminated and/or nephrotoxic . As the new paradigm of value-based care takes hold in the US, cystatin C could prove to be a valuable diagnostic tool for ensuring better patient outcomes at lower costs.
Gentian Cystatin C
Gentian’s cystatin C immunoassaywas launched in 2006. It is a Particle-Enhanced Turbidimetric Immunoassay (PETIA) for in vitro testing of cystatin C in human plasma and serum samples. The test has documented high inter-instrument accuracy on a wide range of clinical chemistry analysers and can be performed in as little as 10 minutes.
Barreto, E. F., Rule, A. D., Murad, M. H., Kashani, K. B., Lieske, J. C., Erwin, P. J., ... & Kane-Gill, S. L. (2019, January). Prediction of the renal elimination of drugs with cystatin C vs creatinine: a systematic review. In Mayo Clinic Proceedings. Elsevier.
*Not cleared for use in pediatric patients in the USA