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On another page on this website, I explained why serum creatinine is the most commonly used screening test for kidney function. And, in another article, I discussed how the “estimated glomerular filtration rate” (eGFR) is calculated from the serum creatinine value.
But, as discussed elsewhere on this website, sometimes, factors other than impairment in renal function can lead to an elevation in serum creatinine. In such situations, what other tests of renal function can be done?
Creatinine clearance
This requires measurement of the serum creatinine level along with the creatine in a 24-hour urine sample.
Isoptopic glomerular filtration rate (GFR)
Cystatin C
This is not affected by factors other than renal function as much as the serum creatinine can be.
Related Pages
What serum creatinine is and why it is important
Can creatine supplements lead to “false” elevation in serum creatinine?
24-hour urine for creatinine clearance
How to collect a 24-hour urine sample
How to interpret the BUN/Creatinine ratio when you get labs back
What is estimated GFR (eGFR)?
What laboratory tests should a mental health clinician order and when?
The 12 Sins in Laboratory Testing in Mental Health
References
Brou NA, Jacqz-Aigrain E, Zhao W. Cystatin C as a potential biomarker for dosing of renally excreted drugs. Br J Clin Pharmacol. 2015 Jul;80(1):20-7. doi: 10.1111/bcp.12602. Epub 2015 May 28. Review. PubMed PMID: 25655191; PubMed Central PMCID: PMC4500321.
Ferguson TW, Komenda P, Tangri N. Cystatin C as a biomarker for estimating glomerular filtration rate. Curr Opin Nephrol Hypertens. 2015 May;24(3):295-300. doi: 10.1097/MNH.0000000000000115. Review. PubMed PMID: 26066476.
Fernandez-Prado R, Castillo-Rodriguez E, Velez-Arribas FJ, Gracia-Iguacel C, Ortiz A. Creatinine Clearance Is Not Equal to Glomerular Filtration Rate and Cockcroft-Gault Equation Is Not Equal to CKD-EPI Collaboration Equation. Am J Med. 2016 Dec;129(12):1259-1263. doi: 10.1016/j.amjmed.2016.08.019. Epub 2016 Sep 6. Review. PubMed PMID: 27612441.
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Onopiuk A, Tokarzewicz A, Gorodkiewicz E. Cystatin C: a kidney function biomarker. Adv Clin Chem. 2015;68:57-69. doi: 10.1016/bs.acc.2014.11.007. Epub 2015 Jan 8. Review. PubMed PMID: 25858868.
Pasala S, Carmody JB. How to use… serum creatinine, cystatin C and GFR. Arch Dis Child Educ Pract Ed. 2017 Feb;102(1):37-43. doi: 10.1136/archdischild-2016-311062. Epub 2016 Sep 19. Review. PubMed PMID: 27647862.
Shahbaz H, Gupta M. Creatinine Clearance. 2019 Jul 5. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019 Jan-. Available from http://www-ncbi-nlm-nih-gov.proxy.library.upenn.edu/books/NBK544228/ PubMed PMID: 31334948.
Shlipak MG, Mattes MD, Peralta CA. Update on cystatin C: incorporation into clinical practice. Am J Kidney Dis. 2013 Sep;62(3):595-603. doi: 10.1053/j.ajkd.2013.03.027. Epub 2013 May 20. Review. PubMed PMID: 23701892; PubMed Central PMCID: PMC3755100.
Stevens LA, Coresh J, Schmid CH, Feldman HI, Froissart M, Kusek J, Rossert J, Van Lente F, Bruce RD 3rd, Zhang YL, Greene T, Levey AS. Estimating GFR using serum cystatin C alone and in combination with serum creatinine: a pooled analysis of 3,418 individuals with CKD. Am J Kidney Dis. 2008 Mar;51(3):395-406. doi: 10.1053/j.ajkd.2007.11.018. PubMed PMID: 18295055; PubMed Central PMCID: PMC2390827.\
Wei L, Ye X, Pei X, Wu J, Zhao W. Diagnostic accuracy of serum cystatin C in chronic kidney disease: a meta-analysis. Clin Nephrol. 2015 Aug;84(2):86-94. Review. PubMed PMID: 26200185.
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