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Epic Test Code N/A Estimated Glomerular Filtration Rate (eGFR)

Important Note

Calculations will not be performed on in-patients or pediatric patients.

Creatinine order required for calculation.

Performing Location(s)

BMC,CRH,LFH,HRK,OCH,FTT,FOX,FCC

Specimen Type

Serum or Plasma

Preferred Container

Gold or Red top tube

Alternate Container

Green top tube

Blood Tube Draw Volume

Min 50% draw volume  

Minumum Volume to Submit for Testing

0.5 mL serum/plasma

  • Multiple test can be performed from this volume. For question please contact the lab at 547-3975.  

Storage Requirements

Sample tubes should be centrifuged within 2 hour of collection followed by transfer of the serum (red or gold top) or plasma (green top) to a labeled plastic, aliquot tube.

See Causes of Rejection for temperature requirements.

Transportation Needs

Deliver specimen to the laboratory within 1 hour of collection. If not possible see “Storage Requirements”

Causes for Rejection

Mislabeled or unlabeled specimen

Less than 50% draw for Vacutainer tubes
>  7 days refrigerated
>  48 hours room temperature
> 6 months Frozen
Hemolysis > 500 mg/dL HgB
Lipemia > 700 mg/dL Trig
Bilirubin > 20 mg/dL Bili

Limitations

Specific clinical settings in which eGFR is not appropriate for use and GFR should be measured directly include:

populations in which the MDRD equation is not validated (eg, Latin, Indigenous, Asian people, pediatrics)

severe malnutrition or obesity

extremes of body size and age (<18 or >70 y.o.)

exceptional dietary intake (eg, vegetarian diet or creatine supplements)

disease of skeletal muscle, paraplegia, etc

rapidly changing kidney function.

 

The eGFR is not an accurate estimate of renal function in hospitalized patients due to the acute clinical status. Use caution in interpreting results in hospitalized patients.

 

N-Acetylcystein (N-AC) interference with this method leading to falsely depresses values. Collecting blood work prior to drug administration and waiting ≥12 hrs for repeat testing is recommended.

Reference Range

Calculation of eGFR without a Race Term:
Since 1999, eGFR equations have incuded race (Black or non-Black) as a coefficient. As race is self-ascribed or socially ascribed on the basis of physical characteristics, such as skin color, and may not directly correlate to the diverse genetic ancestry of communities of color in the United States, use of a race coefficient is problematic and no longer recommended. For more information, see the NKF-ASN Task Force Recommendations.

GFR Estimating Equation Recommended by National Kidney Foundation (NKF) is the 2021 CKD-EPI Equation using Creatinine:
Rationale: The final report of the NKF-ASN Task Force to Reassess the inclusion of Race in Diagnosing Kidney diseased has recommened this equation for the race free estimation of GFR.

Sex

Creatinine

Equation

Female

≤0.7

GFR=143x(Scr/0.7)-0.241x0.994Age

 

>0.7

GFR=143x(Scr/0.7)-1.200x0.994Age

Male

≤0.9

GFR=142x(Scr/0.9)-0.302x0.994Age

 

>0.9

GFR=142x(Scr/0.9)-1.200x0.994Age

  

Interpretation of the estimated GFR (eGFR) and status of chronic kidney disease (CKD) is as follows:

GFR Estimate (ml/min/1.73 m2)

Interpretation

≥ 60

Normal function or mild kidney damage if clinically at risk

30-59

Moderate ¯ GFR

15-29

Severe ¯ GFR

< 15

Kidney failure

 

Glomerular Filtration Rate (GFR) notes

The clinical laboratory automatically calculates glomerular filtration rate (GFR) on all adult out-patients with a creatinine based on legal gender. The GFR is usually accepted as the best overall index of kidney function in health and disease. The formula used and recommended by the 2021 CKD-EPI equation, National Kidney Foundation and American Society of Nephrology. This equation is expected to provide a more accurate estimate of GFR than Creatinine Clearance. It uses serum creatinine in combination with patient age and sex to estimate GFR. The calculation (shown below) will be included on all adult outpatients with a serum creatinine at no charge.

Refer to urinary Albumin:Creatinine ratio (LAB21036) for facilitating appropriate classification of Chronic Kidney Disease, to assess risk of progression and to monitor patients at risk to develop CKD.

The equation may not accurately estimate GFR in pediatric patients (<18 years), patients with normal renal function, patients with unstable creatinine values, or liver transplant patients.

Drug-induced reduction in GFR raises the serum creatinine concentration, and is detected by the CKD-EPI equation. However, drugs that raise serum creatinine concentration without affecting GFR will give falsely low estimates of GFR. In most cases, GFR can be estimated after discontinuing the drug.

Please note, in general, adjustments of drug dosing in the literature and in product labels has been based on calculated creatinine clearance, not on GFR. Dosage adjustments for drugs using GFR may be inaccurate because of this.

 

 

 

 

 

 

More information can be found from the following resources.

 

www.kidney.org

Choosing Wisely:
Use Serum creatinine with eGFR and urinary albumin-creatinine ratio. (Renal Panel, LAB19)

Why is CKD Assessment Important?
Those with chronic kidney disease (CKD) diagnosed by a primary care clinician are more likley to:

  • Avoid risky uses of nonsteroidal anti-inflammatory drugs
  • Use angiotensin-converting-enzyme inhibitors or angiotensin receptor blockers when indicated.
  • Recevie approprate nephrology care

Epidemilogic data have shown that impaired kidney function increases the risk of systemic complications (eg, cardiovascular disease, hypertension, progression to end-stage renal disease, and mortality).

CKD, independent of the cause, is based on 3 or more months of either kidney damage (albuminuria) or an estimated glomerular filtration rate <60 mL/min/1.73 m2.

 

Who should be tested for CKD?

Asymptomatic individuales who are at high risk for CKD should be tested at least annually: diabets, hypertension, family history of kidney disease, and cardiovascular disease.

 

References:

  • Vassalotti JA, Centor R, Turner BJ, Greer RC, Choi M, Sequist TD/ Practical Approach to Detection and Management of Chronic Kidney Disease for the Primary Care Clinician. The American Journal of Medicine 2016;129:153-62.e7.
  • Choosing Wisely Recommendation for Chronic Kidney Disease Testing. 2018. at bit.ly/2SFSz3u
  • Inker LA, Astor BC, Fox CH, ET al. KDOQI US commentary on the 2012 KDIGO clinical practice guidelines for the evaluation and management of CKD. AM J Kidney Dis. 2014;63:713-35

Days of Analysis

All

Available STAT

Yes

Methodology

Calculated from Creatinine and legal gender

CPT Code

82565

Last Updated

5-Jan-23 BHD