What is a Glomerular Filtration Rate (GFR) Test?
GFR full form is Glomerular Filtration Rate. It is a number that indicates how well the kidneys are functioning. GFR meaning in medical terms is simply a measure to understand how well the kidneys can manage and remove waste from the body. GFR test to check kidney function is available widely. Specifically, it estimates how much blood passes through the glomeruli each minute. Glomeruli are the microscopic bundles of blood vessels inside nephrons that acts as tiny sieves in the kidneys that filters waste and excess fluid from the blood.
eGFR is estimated GFR and is a mathematically derived entity based on a patient’s serum creatinine level, age, sex and race.
What is the GFR Test used for?
GFR test is used to diagnose kidney disease, assess kidney damage, and measure the levels at which kidneys are functioning. If a person has GFR below 60 for 3 months or more, they are said to have chronic kidney disease (CKD). Diabetes and high blood pressure can significantly contribute to kidney damage and chronic kidney disease (CKD).
What is the purpose of the GFR test?
The reason why GFR test is done is to measure if the kidneys are functioning at the required level or not. Kidneys remove waste from the body. When they malfunction, toxic waste collects in our body, and can be fatal. GFR test can help diagnose poor kidney function.
Early-stage kidney disease
Early-stage kidney disease shows only a few symptoms. The kidneys still function but not to their full capacity. Symptoms of early-stage kidney disease may include:
- Changes in urination frequency
- Loss of sleep
- Loss of appetite
- Muscle cramps
- Itching persistently
The risk factors that can increase the chances of CKD include:
- High blood pressure
- Heart disease
- Family history of kidney disease
Later stage kidney disease
At this stage, chronic kidney disease reaches an advanced stage. The kidneys no longer function. Symptoms of kidney disease are nonspecific (these symptoms can also be due to other illnesses). Symptoms may not appear until irreparable damage has been done. However, symptoms like the following can be telling symptoms of later-stage kidney disease:
- Swelling of feet and ankles
- Chest pain and shortness of breath due to fluid build-up
- Change in urination frequency
How the Estimated GFR is Calculated?
EGFR meaning can be understood as an estimated GFR. EGFR calculation is done using a formula for GFR. GFR calculation formula requires quantities of creatinine (measured in mg/dL), age, gender, race, etc. EGFR calculators can be found online too. The CKD-EPI Creatinine Equation (2009) is the most popularly used for EGFR calculation. MDRD formula is also used, which is dependent on characteristics of the patient as well as on creatinine levels.
Different formulas are used for adults and children
Different formulas are used for adults and children since the height and weight of the individual affects the EGFR significantly.
EGFR formula includes the following factors:
- Blood creatinine levels
What GFR Test Results Mean?
Using the test results, doctors can estimate whether the kidneys are functioning properly or not. GFR tests results are normal if the number is 90 or higher. There is a GFR normal range for age that needs to be followed.
Normal GFR number
Normal GFR in adults is 90 or above.
Low GFR number
Low GFR number below 90 can mean that the kidney is not functioning properly. It is unable to remove waste from the body efficiently. Usually, numbers lower than 60 are a cause for concern. If they persist for more than three months, it is a sign of chronic kidney disease.
How the Sample is Collected for GFR?
For the EGFR test, a simple blood test is done. They draw a blood sample from a vein in your arm. It takes less than five minutes to do. The blood sample is needed to estimate the amount of creatinine in the blood, which is used for the GFR test.
How to prepare for the test?
One cannot eat any food for several hours before the test. You need to fast without any food or drink, usually overnight so that the creatinine levels are not affected.
What is the Cost of GFR Test in India?
GFR test cost starts in India from as low as INR 350. SRL Diagnostics give an idea of how these tests are done. Any pathology lab in India will offer the GFR test.