Creatinine and Calculated Glomerular Filtration Rate (eGFR) Calculator
Understanding Creatinine and Calculated Glomerular Filtration Rate (eGFR)
Kidney function is crucial for overall health, as these vital organs filter waste products and excess fluid from the blood. The Glomerular Filtration Rate (GFR) is a key indicator of how well your kidneys are working. It measures the volume of fluid that is filtered by the tiny filters in your kidneys (glomeruli) per unit of time. A normal GFR typically decreases with age, but a significant drop can signal kidney disease.
What is Creatinine?
Creatinine is a waste product produced by the normal wear and tear of muscles. It's released into the bloodstream and then filtered out of the body by the kidneys. The amount of creatinine in your blood is influenced by your muscle mass, diet, and kidney function. If your kidneys are not filtering efficiently, creatinine levels in the blood will rise.
What is Calculated Glomerular Filtration Rate (eGFR)?
Directly measuring GFR is complex and not routinely done. Instead, doctors often estimate it using a calculation based on blood creatinine levels, along with other factors like age, sex, and sometimes race (though newer equations are moving away from race). The result is known as the estimated Glomerular Filtration Rate (eGFR).
The eGFR is expressed in milliliters per minute per 1.73 square meters of body surface area (mL/min/1.73 m²). This standardization allows for comparison between individuals with different body sizes. The most commonly used equations for calculating eGFR are the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equations.
How the CKD-EPI Equation Works
The CKD-EPI equation uses your serum creatinine level, age, and sex to estimate your GFR. For example:
- A 65-year-old male with a serum creatinine of 1.0 mg/dL might have an eGFR of approximately 75 mL/min/1.73 m².
- A 70-year-old female with a serum creatinine of 0.8 mg/dL might have an eGFR of around 68 mL/min/1.73 m².
- If the same 65-year-old male had a higher creatinine level of 1.5 mg/dL, his eGFR would drop significantly to about 48 mL/min/1.73 m², suggesting reduced kidney function.
Interpreting Your eGFR Results
Your eGFR provides valuable information about your kidney health:
- eGFR > 90 mL/min/1.73 m²: Generally considered normal, especially in younger individuals.
- eGFR between 60 and 89 mL/min/1.73 m²: May indicate mild kidney damage or be within the expected range for older adults. Further investigation might be needed if other signs of kidney disease are present.
- eGFR < 60 mL/min/1.73 m²: Suggests chronic kidney disease (CKD) and requires medical attention.
- eGFR < 15 mL/min/1.73 m²: Indicates kidney failure, requiring urgent medical management, often including dialysis or transplantation.
It's important to discuss your eGFR results with your healthcare provider. They will consider your eGFR in conjunction with other medical tests, your medical history, and symptoms to make a diagnosis and recommend appropriate treatment.