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eGFR Test

Last updated Oct. 12, 2015

Approved by: Maulik P. Purohit MD MPH

What are the other Names for this Test? (Equivalent Terms)

  • Calculated Glomerular Filtration Rate Test
  • Estimated GFR Test
  • Estimated Glomerular Filtration Rate Test 

What is eGFR Test? (Background Information)

  • Glomerular filtration rate (GFR) is the rate at which kidney glomeruli filter blood, to create pre-urine filtrate. GFR can be measured directly through a direct GFR test or calculated indirectly through the Estimated GFR (eGFR) Test
  • The kidneys, along with the liver and spleen, filter blood and excrete the waste as urine. The site of filtration is a microscopic sieve-like structure, called the glomerulus. There are roughly 1 million glomeruli in each kidney
  • The rate at which the glomeruli filter blood is called the glomerular filtration rate (GFR). When the kidneys and their glomeruli are damaged, GFR may decrease
  • The glomerular filtration rate, and thus kidney function, can be assessed through measuring the excretion of various small proteins, such as creatinine and cystatin C, in the body
  • For the eGFR Test, creatinine is used, which is a byproduct of muscle metabolism. It is produced and excreted at a relatively steady rate, making it a useful marker for GFR. When kidney function decreases, less creatinine is excreted and it accumulates in blood
  • The eGFR Test requires that a creatinine blood test first be performed. Results from the creatinine blood test are then combined with factors, such as the individual’s age, sex, and/or race, and inserted into a formula
  • The Estimated Glomerular Filtration Rate Test utilizes creatinine information obtained through a blood test, to calculate the estimated glomerular filtration rate (eGFR). The eGFR Test assesses kidney function, especially in diabetic individuals; it is used to diagnose kidney disorders 

What are the Clinical Indications for performing the eGFR Test?

Following are the clinical indications for performing the Estimated Glomerular Filtration Rate (eGFR) Test:

  • Evaluating progression and treatment of kidney disorders
  • Evaluating kidney function before administering nephrotoxic drugs
  • Yellowing of the skin
  • Discolored urine, difficulty urinating
  • Urinating, more or less often than usual 

How is the Specimen Collected for eGFR Test?

Following is the specimen collection process for Estimated Glomerular Filtration Rate Test:

Sample required: Blood

Process: Insertion of a needle into an arm vein.

Preparation required: No special preparation is needed prior to the test. 

What is the Significance of the eGFR Test Result?

The significance of Estimated Glomerular Filtration Rate Test is explained:

  • Increased estimated glomerular filtration rate may indicate:
    • Acute tubular necrosis
    • Congestive heart failure
    • Diabetes
    • Exposure to nephrotoxic agents
    • Gigantism
    • Glomerulonephritis (eGFR can either be increased or decreased)
    • Infection
    • Bilateral renal neoplasms
    • Nephrosclerosis
    • Polycystic kidney disease (eGFR can either be increased or decreased)
    • Pyelonephritis
    • Disorder of the kidney vasculature
    • Shock and hypovolemia
    • Tuberculosis
  • Decreased estimated glomerular filtration rate may indicate:
    • Glomerulonephritis (eGFR can either be increased or decreased)
    • Anemia
    • Chronic bilateral pyelonephritis
    • Hyperthyroidism
    • Leukemia
    • Muscle-wasting diseases
    • Paralysis
    • Polycystic kidney disease (eGFR can either be increased or decreased)
    • Shock
    • Urinary tract obstruction 

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario. 

Additional and Relevant Useful Information:

  • The Estimated Glomerular Filtration Rate Test is not an early notification test. At least 50% of kidney function must be lost, before GFR would noticeably decrease
  • Certain factors may interfere with the results of the eGFR Test. These include hydration status and recent exercise. This is because blood flow is routed away from the kidneys, to the muscles during exercise
  • Cystatin C has been shown to vary less with factors, such as age, race, and muscle mass, than creatinine. Cystatin C is a candidate for being a kidney function marker 

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider, the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis. 

What are some Useful Resources for Additional Information?

DoveMed is currently working to bring you additional resources.

Please sign up by creating a DoveMed account to receive periodic notification on information updates. 

References and Information Sources used for the Article:

Lab Tests Online (2014, April 3). Retrieved July 31, 2014 from http://labtestsonline.org/understanding/analytes/gfr/

Martini, F., Nath, J. L., & Bartholomew, E. F. (2012). Fundamentals of anatomy & physiology (9th ed.). San Francisco: Benjamin Cummings.

Schnell, Z. B., Van, L. A., & Kranpitz, T. R. (2003). Davis's Comprehensive handbook of laboratory and diagnostic tests: With nursing implications. Philadelphia: F.A. Davis.

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Aug. 10, 2014
Last updated: Oct. 12, 2015