eGFR (Estimated Glomerular Filtration Rate)

What is eGFR?

Estimated Glomerular Filtration Rate (eGFR) measures how well your kidneys are filtering waste from your blood. It's calculated from your creatinine level, age, sex, and race. eGFR is the best overall measure of kidney function.

Why is it Important?

eGFR is used to:

• Diagnose chronic kidney disease (CKD)
• Determine CKD stage (1-5)
• Monitor kidney function over time
• Adjust medication dosages
• Decide when dialysis or transplant is needed

Normal Ranges (CKD Stages)

Stage	eGFR	Kidney Function
1	≥ 90	Normal (with other signs of damage)
2	60 – 89	Mildly decreased
3a	45 – 59	Mildly to moderately decreased
3b	30 – 44	Moderately to severely decreased
4	15 – 29	Severely decreased
5	< 15	Kidney failure (dialysis or transplant)

What Do Abnormal Results Mean?

Low eGFR (< 60 mL/min/1.73m²)

Indicates reduced kidney function. Common causes include:

• Chronic kidney disease (diabetes, hypertension)
• Acute kidney injury
• Glomerulonephritis
• Polycystic kidney disease
• Prolonged obstruction (kidney stones, enlarged prostate)
• Medications (NSAIDs, certain antibiotics)

High eGFR (> 120 mL/min/1.73m²)

Less common, but can occur with:

• Pregnancy
• High-protein diet
• Early diabetes (hyperfiltration)

Factors Affecting eGFR

• Age: eGFR naturally declines with age (~1 mL/min/1.73m² per year after age 40)
• Muscle mass: Low muscle mass can overestimate kidney function
• Race: Calculation formulas adjusted for Black vs non-Black individuals
• Medications: Some drugs affect creatinine production

When Should You Get Tested?

eGFR is calculated automatically when creatinine is measured. Your doctor may order it if you have diabetes, hypertension, family history of kidney disease, or symptoms like swelling, fatigue, or changes in urination.