Last Updated on October 18, 2025 by Analgesia team
What is Normal GFR
GFR stands for glomerular filtration rate, which is a measure of how well your kidneys are working. The test checks for kidney disease by measuring how much blood your kidneys filter each minute.
What it is
GFR measures the amount of blood filtered by the glomeruli in your kidneys per minute. The glomeruli are tiny blood vessels in the kidneys that act as filters, removing waste products and excess substances while retaining essential proteins and cells.
Why is Glomerular Filtration Rate Important?
GFR is a key indicator of kidney health. It helps diagnose and monitor conditions like chronic kidney disease (CKD) and assess the severity of kidney damage. A normal GFR ensures that your body maintains a healthy balance of fluids, electrolytes, and waste products.
How it’s measured
A normal GRF is usually 90 mL/min or higher, meaning your kidneys are functioning properly. A low GRF result—especially below 60 mL/min—can indicate reduced kidney function or chronic kidney disease (CKD). In severe cases, a GRF below 15 mL/min may suggest kidney failure, requiring dialysis or transplant evaluation.
GRF is often estimated using a blood test for creatinine, a waste product produced by muscle activity. The result is adjusted for age, sex, and body size to give an eGFR (estimated glomerular filtration rate). Monitoring your eGFR helps track kidney function over time and guide treatment decisions.
To maintain a healthy GRF, it’s important to stay hydrated, control blood pressure and blood sugar, and avoid overuse of painkillers like NSAIDs that can harm the kidneys. Regular check-ups can help catch kidney problems early—before symptoms become serious.
What’s a normal GFR
A normal Glomerular Filtration Rate for an adult male is 90 to 120 mL/min, but it varies by age.
GFR stages
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- Stage 1: GFR of 90 or higher, with few or no symptoms
- Stage 2: GFR of 60–89, which may be normal for some people without kidney damage
- Stage 3: GFR of 30–59, which can cause anemia, high blood pressure, and early bone disease
- Stage 4: GFR of 15–29, which indicates severe kidney disease
- Stage 5: GFR of 15 or lower, which indicates end-stage renal disease (ESRD)
What are Normal GFR Levels?
- 90 mL/min or higher: Normal kidney function.
- 60–89 mL/min: Mildly reduced kidney function, often without symptoms.
- Below 60 mL/min: Indicates potential kidney disease.
- Below 15 mL/min: Signals kidney failure, requiring immediate medical attention.
Factors Affecting Glomerular Filtration Rate
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Age: Glomerular filtration rate (GFR) naturally declines as you get older. This is because kidney tissues gradually lose some filtering efficiency over time. Regular monitoring helps detect abnormal drops that may indicate underlying kidney issues rather than normal ageing.
Health conditions: Chronic conditions such as diabetes, high blood pressure, and kidney infections can significantly reduce GFR. These diseases damage the small blood vessels in the kidneys, making it harder for them to filter waste effectively. Managing these conditions early helps preserve kidney function and maintain a healthy GFR.
Medications: Some prescription and over-the-counter drugs can affect kidney function and alter GFR levels. Common examples include NSAIDs, certain antibiotics, and chemotherapy drugs. Always consult your doctor before taking new medications, especially if you have a history of kidney problems.
GFR and kidney disease
- A Glomerular Filtration Rate below 60 for three months or more indicates chronic kidney disease (CKD)
- A Glomerular Filtration Rateof 15 or lower indicates kidney failure, which requires immediate medical attention
The Difference Between eGFR and Measured GFR
Measured GFR (mGFR) is considered the most accurate method for assessing kidney function. It involves injecting a marker substance, such as inulin or iohexol, into the bloodstream and monitoring its clearance rate from the body. This direct measurement precisely reflects the filtration capacity of the kidneys. However, mGFR requires specialised equipment, is time-intensive, and is often reserved for research or cases where absolute precision is necessary.
In contrast, estimated GFR (eGFR) is calculated using a formula that incorporates serum creatinine levels, age, sex, and race. eGFR is less invasive and more practical for routine clinical use, as it only requires a blood test to measure creatinine. While it’s highly effective for identifying kidney dysfunction in most patients, eGFR is an approximation and may be less accurate in certain populations, such as those with unusual muscle mass or extreme body sizes. Ultimately, eGFR is widely used in clinical settings due to its simplicity and accessibility.