In order to maintain healthy functioning, our bodies must expel a variety of substances everyday, including: excess water, bacteria, waste products, and things that simply have no metabolic use. The kidneys are responsible for filtering toxins out of the blood and producing urine to get rid of them. The kidneys do this with approximately a million specialized structures, called nephrons. Each nephron has a microscopic blood filter, called a glomerulus. Estimating a glomerular filtration rate (eGFR) is done by ordering a creatinine (a muscular metabolism waste product) test and measuring how well the glomeruli are filtering it from the blood. The results of the test are used to screen for and detect early kidney damage and to monitor kidney functioning. Creatinine tests are often ordered as part of a comprehensive metabolic panel (CMP), a basic metabolic panel (BMP), or along with a blood urea nitrogen (BUN) test. A healthcare professional may order these tests when warning signs of kidney disease are present, including:
- Swelling around the eyes, face, wrist, abdomen, thighs, or ankles
- Urine that is foamy bloody or coffee-colored
- Changes in frequency or amount of urine
- Mid-back pain
- Hypertension (high blood pressure)
- Tiredness, loss of concentration
- Loss of appetite, nausea, and/or vomiting
- Darkened skin
An eGFR may be done periodically to monitor chronic kidney disease or a condition like diabetes or hypertension that is associated with kidney disease.
A GFR below 60 for three months indicates chronic kidney disease. While you cannot raise your GFR, you can stop it from getting lower. Some tips include:
- Keeping your blood pressure and cholesterol in the optimal range
- If you have diabetes, controlling your blood glucose level
- Limiting intake of salt, alcohol, and tobacco
- Eating heart-healthy foods (fruit, vegetables, whole grains)
- Being more physically active
- If you are overweight, losing weight
High GFR may reflect hyperfiltration, which typically occurs in patients with diabetes mellitus and obesity.
Thus, subgroups of patients at higher cardiovascular risk may have higher GFR than individuals without these cardiovascular risk factors.
Because of its association with cardiovascular risk factors, hyperfiltration may be a marker (but not necessarily a mediator) of future cardiovascular disease.
In the long-term run, hyperfiltration may predispose to glomerular damage and subsequent loss in kidney function, which themselves directly contribute to cardiovascular disease. Prospective clinical data on the association between hyperfiltration, future GFR loss and subsequent cardiovascular disease are scarce.
What can you do to protect your kidney function?
- Get your kidneys checked at least every year. Your healthcare team will do a simple blood test to find out your eGFR. They will also do a urine albumin-to-creatinine ratio (UACR), which shows if you have protein (albumin) in the urine. Protein in the urine may mean you have kidney damage.
- Control blood pressure if you have high blood pressure.
- Control blood sugar if you have diabetes.
- In general, if you have CKD, avoid non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen.
- If you have CKD, tell your healthcare team before having any test that uses contrast dye.
- Do not smoke.
- Exercise and follow a healthy diet that's low in sodium, saturated fat, and sugar, but high in fresh fruits, vegetables, whole grains, lean meats, fish, and poultry. Avoid highly processed foods.
- Stay at a healthy weight. Lose weight if your healthcare team says that you should.
- Discuss any vitamins, minerals, herbs, weight loss or body building supplements with your healthcare team before taking them. Many of these products can hurt your kidneys.
- Make sure that any drugs you take are the right dose for your age and your level of kidney function. You should discuss this with your healthcare team.
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