estimated Glomerular Filtration Rate (eGFR) Blood Tests

The eGFR test, or estimated Glomerular Filtration Rate test, is a crucial laboratory measurement used to assess kidney function. It estimates how well the kidneys are filtering blood and removing waste products. Here's a deeper look into what eGFR signifies and why it is so important:

What is eGFR?

eGFR is calculated from the blood level of creatinine along with other variables such as age, sex, and body size. Creatinine is a waste product produced by muscle metabolism and usually filtered out of the blood by the kidneys.

Why is the eGFR Test Used?

  1. Detecting Kidney Disease: eGFR is primarily used to screen for and monitor kidney disease. Healthy kidneys effectively filter blood, but damaged kidneys may not perform as well, leading to a lower eGFR.
  2. Monitoring Kidney Disease Progression: For patients already diagnosed with kidney disease, regular eGFR tests help monitor the disease's progression. Changes in eGFR over time can indicate whether the kidney function is stable, improving, or worsening.
  3. Guiding Treatment: Kidney function, as measured by eGFR, influences decisions about medication dosages and other treatments. Some drugs are eliminated from the body through the kidneys, and reduced kidney function can affect how drugs are dosed and administered.
  4. Evaluating Risk: A low eGFR indicates poor kidney function and can be associated with an increased risk of other complications like cardiovascular disease and high blood pressure.

How is eGFR Calculated?

The eGFR is typically calculated using the creatinine level along with formulas such as the MDRD (Modification of Diet in Renal Disease) study equation or the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation. These formulas adjust for factors like age, sex, race, and body size to provide a more accurate assessment of kidney function.

Interpretation of eGFR Results

  • Normal Range: Generally, a normal eGFR value is above 90 mL/min/1.73m², indicating good kidney function.
  • Mild to Moderate Decrease: An eGFR between 60 and 89 might suggest some kidney damage, particularly if other signs of kidney disease are present.
  • Moderate to Severe Decrease: An eGFR below 60 may indicate chronic kidney disease.
  • Severe Decrease: An eGFR below 30 suggests more serious kidney disease, potentially nearing kidney failure.
  • Kidney Failure: An eGFR less than 15 typically indicates kidney failure, necessitating dialysis or transplantation for continued survival.

Regular monitoring of eGFR is essential for patients with known risk factors for kidney disease, such as diabetes and hypertension.

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