Estimating and Reporting GFR

Estimating GFR

Estimated GFR (eGFR) is a key method for identifying people with chronic kidney disease (CKD). eGFR calculated using the Modification of Diet in Renal Disease (MDRD) Study equation provides a more clinically useful measure of kidney function than serum^* creatinine alone. This equation takes into account several factors that impact creatinine production, including age, gender, and race. Read about using the MDRD Study equation, reducing rounding errors when estimating GFR, and when not to use creatinine-based equations to estimate GFR.

The serum/plasma creatinine standardization initiative has been successful and nearly all methods from the major global manufacturers selling measurement systems in North America and other regions are now only selling products with calibration traceable to an IDMS reference measurement procedure.¹ Standardized creatinine results contribute to more consistent eGFR values from different laboratories.

Get information about estimating GFR in the context of creatinine standardization:

• Clinical laboratories
• IVD manufacturers
• PT/EQA providers
• Pharmacists and authorized drug prescribers
• National metrology institutes, reference laboratories, and JCTLM organizational members
• Software vendors

Information on the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation.

^*Note that "serum" is used in the text, but the information also applies to plasma and whole blood creatinine results because methods should be calibrated to give equivalent creatinine results for all these sample types.

Reporting GFR

NKDEP supports routine reporting of eGFR with all serum creatinine results for patients 18 and older, when appropriate and feasible. Serum creatinine is measured frequently, so routine reporting of eGFR can help facilitate early detection of CKD. Where possible, laboratories should program their information systems to use the MDRD Study equation to calculate and automatically report eGFR. Read more about common problems in reporting, how to report values over 60 mL/min/1.73m², and view sample reports.

Equations and Calculators

NKDEP provides eGFR calculators and their equations. Laboratories that do not report eGFR with serum creatinine can direct providers to NKDEP's online calculator, enabling them to estimate eGFR on their own. For adults, providers will need to enter the patient's serum creatinine result, age, gender, and race.

References

1. Miller WG. Estimating glomerular filtration rate. Clin Chem Lab Med 2009;47:1017-19).