Glomerular Filtration Rate, Estimated (eGFR)

TEST: 100768
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CPT: 82565
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Synonyms

  • eGFR
  • Estimated Glomerular Filtration Rate
  • GFR, Estimated

Test Includes

Creatinine, serum; eGFR calculation

Expected Turnaround Time

Within 1 day

Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.

Related Documents

Specimen Requirements

Specimen

Serum (preferred) or plasma

Volume

1 mL

Minimum Volume

0.7 mL (Note: This volume does not allow for repeat testing.)

Container

Red-top tube, gel-barrier tube, or green-top (lithium heparin) tube. Do not use oxalate, EDTA, or citrate plasma.

Collection

If a red-top tube or plasma is used, transfer separated serum or plasma to a plastic transport tube.

Storage Instructions

Maintain specimen at room temperature.1

Stability Requirements

Temperature

Period

Room temperature

14 days

Refrigerated

14 days

Frozen

14 days

Freeze/thaw cycles

Stable x3

Causes for Rejection

Hemolysis; improper labeling

Test Details

Use

The estimated glomerular filtration rate (eGFR) provides an assessment of the filtering capacity of the kidney. Measuring serum creatinine along with an estimated glomerular filtration rate (eGFRcr) is recommended as the first step in GFR evaluation by current clinical practice guidelines.2,3 The eGFR is calculated from a serum creatinine using the CKD-EPI 2021cr equation, which does not include a race coefficient. The National Kidney Foundation and the American Society of Nephrology's Task Force on Reassessing the Inclusion of Race in Diagnosing Kidney Diseases recommends calculating estimated glomerular filtration rate (eGFR) without a race coefficient using the CKD-EPI 2021cr equation since it does not include race in the calculation and reporting, includes diversity in its development, and has acceptable performance characteristics and potential consequences that do not disproportionately affect any one group of individuals.4

The eGFR has been shown to be more accurate in estimating the glomerular filtration rate than a 24-hour urine collection for creatinine clearance.5 Among patients with chronic kidney disease (CKD), the eGFR is instrumental in determining the stage of disease according to the K/DOQI CKD classification.

GFR categories in CKD

GFR Category

(mL/min/1.73 m2)

Terms

Abbreviations: CKD, chronic kidney disease; GFR, glomerular filtration rate

*Relative to young adult level

In the absence of evidence of kidney damage, neither GFR category G1 nor G2 fulfill the criteria for CKD.

G1

≥90

Normal or high

G2

60–89

Mildly decreased*

G3a

45–59

Mildly to moderately decreased

G3b

30–44

Moderately to severely decreased

G4

15–29

Severely decreased

G5

<15

Kidney failure

Limitations

All estimates of GFR based on serum creatinine will be less accurate for patients at the extremes of muscle mass (including frail elderly, critically ill, or cancer patients), those with unusual diets, and those with conditions associated with reduced secretion or extrarenal elimination of creatinine. The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines recommends using additional tests (such as cystatin C) for confirmatory testing in specific circumstances when eGFR based on serum creatinine is less accurate.2

Methodology

Kinetic Jaffe

Reference Interval

>59 mL/minute/1.73 m2

Additional Information

While a normal GFR in young adults is approximately 120−130 mL/minute/1.73 m2, it declines with age, and values <60 mL/minute/1.73 m2 for three months or more is defined as CKD. To determine the presence of proteinuria, low eGFR results may be followed up with albumin:creatinine ratio. An albumin:creatinine ratio >30 mg/g would be indicative of kidney damage.5

Footnotes

1. Labcorp internal studies.
2. International Society of Nephrology. Kidney Disease Supplements. KDIGO (Kidney Disease Improving Global Outcomes) 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Accessed at https://kdigo.org/wp-content/uploads/2017/02/KDIGO_2012_CKD_GL.pdf.
3. Inker LA, Astor BC, Fox CH, et al. KDOQI US Commentary on the 2012 KDIGO Clinical Practice Guideline for the Evaluation and Management of CKD. Am J Kidney Dis. 2014 May;63(5):713-735.24647050
4. Delgado C, Baweja M, Crews DC, et al. A Unifying Approach for GFR Estimation: Recommendations of the NKF-ASN Task Force on Reassessing the Inclusion of Race in Diagnosing Kidney Disease. Am J Kidney Dis. 2022 Feb;79(2):268-288.e1.34563581
5. National Kidney Foundation. K/DOQI clinical practice guidelines for chronic kidney disease: Evaluation, classification, and stratification. Am J Kidney Dis. 2002 Feb;39(2 Suppl 1):S1-266.11904577

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
100768 Glom Filt Rate, Estimated 45066-8 001370 Creatinine mg/dL 2160-0
100768 Glom Filt Rate, Estimated 45066-8 100779 eGFR mL/min/1.73 98979-8

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