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Creatinine-based Estimated Glomerular Filtration Rate (eGFR)

Creatinine-based Estimated Glomerular Filtration Rate (eGFR)

Test Summary

Creatinine-based Estimated Glomerular Filtration Rate (eGFR)

  

Clinical Use

  • Detect chronic kidney disease (CKD) in adults

  • Monitor CKD therapy and/or progression in adults

Clinical Background

More than 35 million people in the United States are currently affected by CKD,1 and the prevalence of ensuing kidney failure is rising. Since evidence has shown that treatment at earlier stages is generally effective in preventing or delaying adverse outcomes, monitoring patients with and at risk of CKD becomes critically important for decreasing morbidity and mortality.

CKD is defined by the presence of glomerular filtration rate (GFR) <60 mL/min/1.73m2 for >3 months and/or evidence of kidney damage (eg, structural abnormalities, histologic abnormalities, albuminuria, urinary sediment abnormalities, renal tubular disorders, and/or history of kidney transplantation) for >3months.1 Thus, monitoring should include tests for GFR, albuminuria, and urine sediment.

GFR has traditionally been estimated using the 24-hour creatinine clearance; however, a calculation of estimated glomerular filtration rate (eGFR) is now recommended by the National Institutes of Health (NIH) and the National Kidney Foundation. eGFR, based on serum creatinine and/or cystatin C, is a simpler and generally more reliable test.

Individuals Suitable for Testing

  • Adults aged 18 years and older who are at risk of or who have CKD

Individuals with diabetes, hypertension, autoimmune disease, systemic infections, and family history of kidney disease are some of those at increased risk.

This test is not suitable for people with unstable creatinine concentrations such as seen in patients hospitalized with acute illness, in pregnant women, and in those with serious comorbid conditions. Nor is this test suitable for people with extremes of muscle mass, ie, amputees, paraplegics, bodybuilders, patients with muscle-wasting disease, and patients with a neuromuscular disorder. This test is also not suitable for obese people, patients suffering from malnutrition, those with a vegetarian or low-meat diet, and those taking creatine dietary supplements. Cystatin C is a suitable alternative for these patients.

Test Order Codes

Table 1. Tests that Include eGFR
Test Name Test Code

BUN/Creatinine Ratio

Includes BUN and creatinine and calculated BUN/creatinine ratio and eGFR.

296(X)

Creatinine

Includes serum creatinine and eGFR calculation.

375(X)

Creatinine Clearance

Includes serum and urine creatinine and creatinine clearance and eGFR calculation.

7943(X)

Basic Metabolic Panel

Includes BUN/creatinine ratio (calculated), calcium, carbon dioxide, chloride, creatinine, eGFR (calculated), glucose, potassium, sodium, and urea nitrogen (BUN).

10165(X)

Comprehensive Metabolic Panel

Includes albumin, albumin/globulin ratio (calculated), alkaline phosphatase, ALT, AST, BUN/creatinine ratio, calcium, carbon dioxide, chloride, creatinine, eGFR (calculated), globulin (calculated), glucose, potassium, sodium, total bilirubin, total protein, and urea nitrogen.

10231(X)

Renal Function Panel

Includes albumin, BUN/creatinine ratio (calculated), calcium, carbon dioxide, creatinine, estimated GFR (calculated), glucose, phosphate (as phosphorous), potassium, sodium, and urea nitrogen (BUN).

10314(X)

Method

The eGFR is calculated using isotope dilution mass spectrometry (IDMS)-traceable serum creatinine measurements and the patient’s age (18 years and older), gender, and race (African American vs non-African American) according to the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation.2 Alternative calculations have been proposed for patients under age 18 years, but they are not offered by Quest Diagnostics at present. Quest Diagnostics test codes that include eGFR are listed in Table 1.

Interpretive Information

Table 2  provides interpretation of specific eGFR values. Creatinine measurements, and therefore eGFR calculations, are affected by very high or very low muscle mass, muscle injury, a diet very high in meat, hepatic cirrhosis, certain drugs, etc.

Table 2. Interpretation of eGFR Values1,a

eGFR (mL/min/1.73m2)

Interpretation

90

Normal

60-89 Mild decrease
45-59 Mild to moderate decrease
30-44 Moderate to severe decrease
15-29 Severe decrease
<15 Kidney failure
eGFR, estimated glomerular filtration rate.
a This table applies to creatinine-based and cystatin C-based eGFR.

References

  1. Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2012 clinical practice guideline for the evaluation and management of chronic kidney disease. Kidney Inter Suppl. 2013;3:1-150. http://www.kdigo.org/clinical_practice_guidelines/pdf/CKD/KDIGO_2012_CKD_GL.pdf  Accessed March 25, 2013.

  2. Levey AS, Stevens LA, Schmid CH, et al; CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration). A new equation to estimate glomerular filtration rate. Ann Intern Med. 2009;150:604–612. Erratum in: Ann Intern Med. 2011;155:408.
     

Content reviewed 04/2013
 
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* The tests listed by specialist are a select group of tests offered. For a complete list of Quest Diagnostics tests, please refer to our Directory of Services.