The proper function of your kidneys is important. Chronic kidney disease (CKD) affects more than one in seven US adults, many of them with diabetes and/or high blood pressure. In the early stages, CKD often has no symptoms, and you may not know you have it until you need dialysis or a transplant.
Monitoring the health of your kidneys is particularly important if you have diabetes, high blood pressure, heart disease, or a family history of kidney failure. As early kidney problems have no symptoms, testing is important.
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There are several causes of chronic kidney disease. The most common include:
Diabetes: Unmanaged diabetes causes damage to many organs over time and puts particular strain on your kidneys
High blood pressure: If not well controlled, high blood pressure can damage your kidneys, which can then contribute to further hypertension
Polycystic kidney disease: A common inherited disease that causes cysts to form in the kidneys, which damage surrounding tissue
Glomerulonephritis: A group of diseases, such as infections or autoimmune conditions, that cause inflammation in your kidneys’ vital filtering units
Congenital deformities of the kidney or urinary tract: One common problem is a narrowing of the urinary tract, preventing the normal flow of urine. Urine will then flow back into the kidney, causing infections.
Autoimmune diseases such as lupus nephritis: Cause swelling or scarring of the small blood vessels in the kidneys
Repeated urinary tract infections: This can damage the kidneys over time
Enlarged prostate in men: Interfering with normal urine flow
Obstructions: Caused by kidney stones or tumors
There are two main kinds of kidney function tests:
A urine test: This checks for albumin, a protein normally found in your blood. Healthy kidneys do not excrete albumin, so the presence of albumin in your urine indicates that your kidneys are damaged. This is done using either a simple dipstick test or a urine albumin-to-creatine ratio (UACR) test, which estimates how much albumin passes into your urine in 24 hours. 30 mg/g or less is normal.
A blood test: This measures your glomerular filtration rate (GFR) and directly indicates how well your kidneys are filtering your blood. A reading of 90 or more is the normal range. Less than 60 may mean you have kidney disease. A reading of 60 to 90 can indicate kidney disease, but this reading can be normal for some people, especially older people, as it is normal for GFR to decline with age.
Note that both tests can show temporary abnormal results. You will likely repeat the test to confirm the results if you have albumin in your urine. The second test is usually the UACR test, which is more accurate.
Kidney disease is diagnosed if the GFR remains low for three or more months and/or if there is also protein in your urine. There are a few factors that can temporarily change your GFR, including:
Certain athletic training, including bodybuilding: If you have high muscle mass, this can affect your apparent GFR by increasing the amount of serum creatinine. If you are "bulked up," your doctor might use a different test based on cystatin C.
Pregnancy:¹ A normal pregnancy results in increased GFR (by about 50%) to compensate for the demands made by the fetus.
Fluid levels: Increased water intake decreases GFR, despite what you might expect. You may be asked not to drink water or drink less water for a certain time before a kidney function test.
You can get a home kidney test if you are at high risk of kidney disease. Home tests check for protein in your urine with a simple test, and a smartphone app sends the results to your doctor. These tests are available from pharmacies.
Before you buy one, talk to your doctor about using them and discuss how often you should carry out a test. Be aware that home testing can cause anxiety. Urine protein levels can be temporarily elevated by factors such as:
Eating a lot of meat
However, home testing can be useful if you are borderline for having CKD or at very high risk as it reduces the number of trips to the doctor. Many people are more compliant with a home-testing regimen than with repeated doctor's visits.
If you live in a rural area and have a long journey to your doctor, it's worth discussing home testing to save time. For some people, it is the only feasible way to test regularly or to do follow-up tests after an office test shows a potential problem.
Chronic kidney disease cannot be reversed. Acute kidney disease often can improve, with several months of a special diet and medication, even if you temporarily go on dialysis. Full-blown kidney failure cannot be reversed.
However, the sooner CKD is diagnosed, the better. While the damage can't be reversed or cured, it is possible to significantly slow or even stop the progression of the disease.
Treating kidney failure requires dialysis or a transplant. While there is less of a kidney shortage than other organs, as healthy people can donate one of their kidneys, many people face years of dialysis if they do not slow the progression of CKD.
Dialysis is when a machine is used to filter out the toxins in your blood, to substitute the work of the kidneys, and is a major impediment to your quality of life. Hemodialysis, for example, requires that you spend four hours, three times a week, attached to a dialysis machine.
Peritoneal dialysis, where the lining of your abdominal cavity is used to filter the blood instead of an external machine, can be more convenient, but not everyone is a candidate.
Also, kidney failure increases your risk of many other medical conditions, including cardiovascular disease and depression.
Diagnosing CKD early means you can take steps to slow the progression of the disease. These steps are designed to reduce the strain on weakened kidneys and include:
Limiting sodium to no more than 2,300mg per day. Note that many salt substitutes contain potassium, and you may be told not to use them if you are on certain medications.
Moderating protein intake. You should only consume the protein you need.
Limiting dietary phosphorus and potassium. A good first step is to avoid food with phosphate additives.² This includes processed meat, sausages, canned fish, soft drinks, and baked goods.
Exercising for 20 to 30 minutes every day, including both aerobic and strength training
Controlling your blood pressure
Using angiotensin-converting-enzyme (ACE) inhibitors and/or angiotensin receptor blockers (ARBs); both control blood pressure and reduce albumin levels
Controlling your blood sugar if you have diabetes
Again, the earlier you get a diagnosis, the better. Damage from CKD cannot be reversed, but it can be slowed.
In the early stages, CKD has no symptoms and needs to be diagnosed through testing. The first symptoms do not show up until the disease is well advanced. However, you should still keep an eye out for them.
Symptoms of kidney disease include:
Trouble sleeping and/or sleep apnea
Dry, itchy skin
Increased need to urinate, especially at night. However, this is more likely a sign of a urinary tract infection if you are female or an enlarged prostate if you are an older male.
Blood in your urine can also be a sign of tumors, kidney stones, or an infection
Bubbles in your urine are caused by elevated albumin levels
Persistent puffiness around your eyes
Swollen ankles and/or feet
Increased muscle cramps
Most of these are not specific to kidney disease, but you should get them checked out anyway. If you experience these symptoms after a blow to the lower back or a fall, this might indicate physical damage to your kidneys.
Chronic kidney damage is not repairable; if your kidneys fail, there is no (current) way to fix them.
However, kidneys can repair themselves from acute damage due to infection, medication, physical damage, hospitalization in intensive care, and other causes. This may require temporary dialysis to take the strain off your kidneys while they recover.
The primary treatment for acute damage is to treat the underlying cause. For example, if your kidney damage is caused by an infection, you will need antibiotics. If the damage is caused by medication, you may need to stop taking the medication or switch to a different one. Acute damage can lead to chronic kidney disease even if treated, but most people recover with treatment.
You should talk to a doctor about kidney function testing if you have risk factors. Diabetics and people with hypertension should have their kidney function tested once a year.
The American College of Physicians³ recommends against screening healthy adults without risk factors. However, they recommend that screening be considered for the following people:
Aged 60 years or older
With cardiovascular disease, hypertension, or diabetes
Certain races such as African Americans, Hispanics, Asians/Pacific Islanders, and American Indians
With a history of acute kidney injury
On kidney toxic medication
With a family history of CKD
You should talk to a doctor if you have any of the first signs of kidney problems listed above. Be aware that if you do not have risk factors for kidney disease, your symptoms are more likely caused by something else. For example, blood in your urine is more likely to be a urinary tract infection or a kidney stone. Try not to be alarmed by these symptoms, but it's important to get checked out.
You should always talk to your doctor before purchasing a home kidney function test, especially if you are not diabetic and don't have high blood pressure. Routine home screening can increase anxiety about your health.
You can monitor your kidney health through home tests. However, most people do not need to and are likely to become anxious about temporary or unusual results.
Home tests are a good idea for people who need regular screening, such as diabetics, who would like to reduce the number of visits to their doctor. Testing at home can be particularly valuable if you live in a rural area and travel far to get medical care.
Discuss with your doctor whether monitoring your kidneys at home is right for you.
Chronic kidney disease (CKD) | National Kidney Foundation
Chronic kidney disease tests & diagnosis | NIH: National Institute of Diabetes and Digestive and Kidney Diseases
Sudden loss of kidney function: Do you know what to do in this emergency? | National Kidney Foundation
How it's performed | NHS
Slow progression & reduce complications | NIH: National Institute of Diabetes and Digestive and Kidney Diseases
10 signs you may have kidney disease | National Kidney Foundation
Acute kidney injury | NHS
Just add water (2008)