Methods of Estimating GFR - Different Equations Including CKD-EPI.

Area of Science:

• Nephrology
• Clinical Chemistry
• Biomarker Development

Background:

• Plasma creatinine alone has limitations for estimating glomerular filtration rate (GFR).
• Gold standard GFR measurements (inulin, radionuclides) are complex and costly.
• 24-hour urine creatinine clearance measurements have inherent inaccuracies.

Purpose of the Study:

• To outline the evolution of estimated GFR (eGFR) calculation methods.
• To highlight the adoption and refinement of creatinine-based eGFR formulas.
• To introduce newer equations like CKD-EPI and the potential of Cystatin C.

Main Methods:

• Review of recommendations from the Australasian Creatinine Consensus Working Group.
• Implementation of automated eGFR calculation using the abbreviated MDRD formula.
• Evaluation of updated plasma creatinine assay standardization.
• Introduction of the CKD-Epidemiology Collaboration (CKD-EPI) equation.

Main Results:

• The abbreviated MDRD formula was widely adopted for eGFR estimation in adults over 18.
• Updated recommendations in 2007 addressed plasma creatinine assay standardization.
• The CKD-EPI equation demonstrates reduced underestimation of GFR in individuals with normal renal function.
• Cystatin C-based equations show promise for specific clinical scenarios.

Conclusions:

• Automated eGFR calculation has become standard practice, improving renal function assessment.
• The CKD-EPI equation represents an advancement over previous methods, particularly for normal GFR.
• Cystatin C offers a potential alternative or adjunct for GFR estimation in select patient populations.