Your kidneys have an important job. These two small organs filter your blood constantly, removing waste products. They also remove extra water from your body by making and excreting urine.
Over time, chronic health conditions like diabetes and high blood pressure may damage your kidneys. Chronic kidney disease (CKD) may also develop if kidney disease runs in your family. When the kidneys become damaged, they’re no longer able to filter your blood as they should.
If your doctor suspects you have kidney disease, they use certain tests to confirm a diagnosis. Testing for kidney function includes:
- Blood tests to check your glomerular filtration rate (GFR).
- Tests to check levels of a certain protein called albumin in your urine. Too much albumin in your urine means your kidneys aren’t functioning as they should.
Results from these tests help your doctor diagnose chronic kidney disease. If you have CKD, they also tell your doctor whether treatment is helping or if your kidney function is declining. Using GFR, your doctor can determine if you have end-stage kidney disease (kidney failure).
What Is Glomerular Filtration Rate (GFR)?
Your kidneys contain blood vessels, known as glomeruli, that filter your blood. How much waste product they filter — and how quickly — depends on how healthy your kidneys are.
Doctors use a mathematical formula to estimate this function. They assign a number to the estimate, known as your glomerular filtration rate (GFR).
To find your GFR, a healthcare provider uses a syringe with a needle to draw a blood sample. They examine the sample to see how much of a certain waste product (creatinine) is in your blood. Once they know your creatinine level, they consider other factors like your age, height, sex, and weight to estimate your GFR.
Your GFR shows how quickly your kidneys clear creatinine and other waste products. Experts measure this rate in milliliters (mL) per minute. So, if your GFR is 90, your kidneys clear waste products at a rate of 90 mL per minute.
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What Do GFR Numbers Mean?
Your GFR number helps your doctor know if you are showing signs of kidney disease. Typically, if you have normal kidney function, your GFR will be around 90 or higher. Some people, including elderly people and babies, may have a GFR between 60 and 89 but may not have kidney disease.
But lower GFR ranges may signal a loss of kidney function associated with chronic kidney disease:
- If your GFR is between 30 and 59, you likely have mild to moderate chronic kidney disease (CKD).
- If your GFR is between 15 and 29, you likely have severe CKD.
Does a Low GFR Mean You Have Kidney Failure?
As chronic kidney disease (CKD) progresses, your GFR typically gets worse (declines). A GFR number of 15 or less indicates kidney failure. If your GFR is 15 or under, you’ll need treatment for CKD right away.
With a GFR of 15 or lower, you may experience kidney failure symptoms, such as:
- Cramping in your muscles.
- Decreased appetite.
- Foamy urine.
- Nausea and vomiting.
- Producing less urine than is typical for you.
- Shortness of breath.
- Skin rash or itchy skin.
- Swollen ankles or feet.
What Treatments Are Available for Kidney Failure?
Your doctor will talk with you about your GFR number and what it means for your kidney function. If you have kidney failure, you have the following treatment options:
Kidney dialysis is a way to remove waste products from your blood when your kidneys can no longer do their job. There are two types of kidney dialysis:
- Hemodialysis: You’re connected to a machine that filters your blood and does the work of your kidneys. You usually have this treatment about three times per week. Typically, you’ll have this treatment at the hospital or at a dialysis center.
- Peritoneal dialysis: Using a thin tube (catheter), you fill your abdomen with a special solution (dialysate). Your abdominal lining (peritoneum) and the solution help filter waste from your blood. You can do this treatment at home, which means you don’t have to travel, but you must do it several times daily.
If your GFR continues to decline when you’re on dialysis or if dialysis isn’t right for you, kidney transplant may help. During this surgery, doctors replace your failing kidney with a healthy kidney from a donor. Healthy kidneys may come from a deceased donor or a living kidney donor.
Kidney transplant can help save your life if your GFR shows you’re in kidney failure. This surgery can restore healthy kidney function and improve your health.
If you’ve had kidney transplant surgery, your doctor will check your GFR to make sure your new kidney is functioning as it should. GFR helps show whether your body has accepted the donated kidney.
What Can I Do to Improve My GFR?
Chronic kidney disease (CKD) isn’t curable. If you’re in kidney failure, you need treatment.
If you have early to moderate CKD, you may be able to keep it from getting worse (progressing) by making lifestyle changes. These changes may also improve your GFR.
Some ways to help keep your kidneys healthy are:
- Don’t smoke or use nicotine products.
- Eat a healthy, low-salt diet and avoid processed foods.
- Move your body regularly and stay at a healthy weight.
Talk to Your Doctor About Your GFR Number
Your GFR is an important measure of your kidney health. If your GFR indicates early to moderate kidney disease, ask your doctor what you can do to stay as healthy as possible. Your doctor will test your GFR regularly to check your kidney health over time.
Learning that your GFR number shows you’re in kidney failure can be scary. But there are treatment options available. Talk to your doctor about the treatment that’s best for you.
MedlinePlus, Glomerular Filtration Rate, Link
National Institute of Diabetes and Digestive and Kidney Diseases, Chronic Kidney Disease (CKD), Link
National Institute of Diabetes and Digestive and Kidney Diseases, Glomerular Filtration Rate (GFR), Link
National Institute of Diabetes and Digestiveand Kidney Diseases, Peritoneal Dialysis, Link
National Institute of Diabetes and Digestive and Kidney Diseases, Your Kidneys & How They Work, Link
National Kidney Foundation, Estimated Glomerular Filtration Rate (eGFR), Link
StatPearls, End-Stage Renal Disease, Link
StatPearls, Renal Function Tests, Link
UPMC, Glomerular Filtration Rate (GFR) Calculator and FAQ, Link
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