Glomerular Filtration Rate, Estimated (eGFR)

CPT: 82565
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Test Details

Synonyms

  • eGFR
  • Estimated Glomerular Filtration Rate
  • GFR, Estimated

Test Includes

Creatinine, serum; eGFR calculation

Use

The estimated glomerular filtration rate (eGFR) provides an assessment of the filtering capacity of the kidney. The eGFR is calculated from a serum creatinine using the CKD EPI equation.2 Aside from the serum creatinine, other variables required for the equation are sex, age, and race. The eGFR has been shown to be more accurate in estimating the glomerular filtration rate than a 24-hour urine collection for creatinine clearance.3 Among patients with chronic kidney disease (CKD), the eGFR is instrumental in determining the stage of disease according to the K/DOQI CKD classification.

Association of Glomerular Filtration Rate (GFR) and Staging of Kidney Disease*

GFR

(mL/min/1.73 m2)

With

Kidney Damage

Without

Kidney Damage

*Each stage assumes the associated GFR level has been in effect for at least three months. Stages 1 to 5, with or without kidney disease, indicate chronic kidney disease.

Note: Determination of stages one and two (with eGFR >59 mL/minute/1.73 m2) requires estimation of kidney damage for at least three months as defined by structural or functional abnormalities of the kidney, manifested by either:

• Pathological abnormalities or

• Markers of kidney damage, including abnormalities in the composition of the blood or urine or abnormalities in imaging tests

>90

Stage one

Normal

60−89

Stage two

Decreased GFR

30−59

Stage three

Stage three

15−29

Stage four

Stage four

<15

(or dialysis)

Stage five

Stage five

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. Confirmatory tests with exogenous measured GFR or measured creatinine clearance should be performed for people in whom estimates based on serum/plasma/blood creatinine alone may be inaccurate.4

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.3

Specimen Requirements

Specimen

Serum (preferred) or plasma

Volume

1 mL

Minimum Volume

0.5 mL

Container

Red-top tube, green-top (heparin) tube, or lavender-top (EDTA) tube

Collection

Separate serum from cells within 45 minutes of collection.

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

Clinical Information

Footnotes

1. LabCorp Internal Studies.
2. Levey AS, Stevens LA, Schmid CH, et al, for the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration). A new equation to estimate glomerular filtration rate. Ann Intern Med. 2009 May 5; 150(9):604-612. Erratum: 2011 Sep 20; 155(6):408. 19414839
3. 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-S266. 11904577
4. Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976; 16(1):31-41. 1244564

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
100768 Glom Filt Rate, Estimated 001370 Creatinine, Serum mg/dL 2160-0
100768 Glom Filt Rate, Estimated 100791 eGFR If NonAfricn Am mL/min/1.73 62238-1
100768 Glom Filt Rate, Estimated 100797 eGFR If Africn Am mL/min/1.73 62238-1

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The LOINC® codes are copyright © 1994-2017, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee. Permission is granted in perpetuity, without payment of license fees or royalties, to use, copy, or distribute the LOINC® codes for any commercial or non-commercial purpose, subject to the terms under the license agreement found at https://loinc.org/license/. Additional information regarding LOINC® codes can be found at LOINC.org, including the LOINC Manual, which can be downloaded at LOINC.org/downloads/files/LOINCManual.pdf