Understanding Glomerular Filtration Rate (GFR)
The Glomerular Filtration Rate (GFR) is a crucial test that indicates how well your kidneys are functioning. It measures the amount of blood that filters through your glomeruli each minute. The glomeruli are tiny filters in your kidneys that remove waste and excess fluid from your blood.
A normal GFR varies with age, but generally, a higher GFR indicates better kidney function. As kidney function declines, the GFR also decreases. Doctors use GFR to stage chronic kidney disease (CKD) and to monitor the progression of kidney damage.
How is GFR Calculated?
GFR is typically estimated using formulas that take into account your serum creatinine level, age, gender, and race. Serum creatinine is a waste product found in your blood that your kidneys filter out. Higher creatinine levels often suggest poorer kidney function.
The most commonly used equation for estimating GFR is the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation. This calculator uses a simplified version of this estimation.
Interpreting Your GFR Results
- GFR 90 or higher: Usually normal and indicates good kidney function. However, if there are other signs of kidney damage (like protein in the urine), it could still indicate kidney disease.
- GFR between 60 and 89: May indicate mild to moderate kidney damage.
- GFR below 60: Suggests significant kidney damage and is considered a marker for Chronic Kidney Disease (CKD).
- GFR 15 or lower: Indicates kidney failure, and a person would likely need dialysis or a kidney transplant.
It's important to discuss your GFR results with your healthcare provider. They will interpret the results in the context of your overall health, medical history, and other diagnostic tests.
Example Calculation
Let's consider an example: A 65-year-old male of White race with a serum creatinine level of 1.2 mg/dL.
Using a standard CKD-EPI equation (simplified for illustrative purposes here), his estimated GFR would be calculated. If his serum creatinine was 1.2 mg/dL, age 65, gender male, and race white, the estimated GFR would be approximately 75 mL/min/1.73m².
This suggests a mild decrease in kidney function, which would warrant further discussion with a doctor to monitor and manage.