Overview

What is kidney disease? An expert explains

Learn more from kidney doctor Andrew Bentall, M.D.

I'm Dr. Andrew Bentall, a kidney doctor at Mayo Clinic. I look after patients with kidney disease, either in the early stages, or with more advanced kidney disease considering dialysis and transplantation as treatment options. In this video, we'll cover the basics of chronic kidney disease. What is it? Who gets it? The symptoms, diagnosis and treatment. Whether you are looking for answers for yourself or for someone you love, we're here to give you the best information available.

Chronic kidney disease is a disease characterized by progressive damage and loss of function in the kidneys. It's estimated that chronic kidney disease affects about one in seven American adults. And most of those don't know they have it. Before we get into the disease itself, let's talk a little bit about the kidneys and what they do. Our kidneys play many important roles keeping our bodies in balance. They remove waste and toxins, excess water from the bloodstream, which is carried out of the body in urine. They helped to make hormones to produce red blood cells, and they turn vitamin D into its active form, so it's usable in the body.

There are quite a few things that can cause or put you at higher risk for chronic kidney disease. Some of them are not things that can be avoided. Your risk is simply higher if you have a family history of certain genetic conditions like polycystic kidney disease or some autoimmune diseases like lupus or IgA nephropathy. Defects in the kidney structure can also cause your kidneys to fail, and you have an increased risk as you get older. Sometimes, other common medical conditions can increase your risk. Diabetes is the most common cause of kidney disease. Both type 1 and type 2 diabetes. But also heart disease and obesity can contribute to the damage that causes kidneys to fail. Urinary tract issues and inflammation in different parts of the kidney can also lead to long-term functional decline. There are things that are more under our control: Heavy or long-term use of certain medications, even those that are common over-the-counter. Smoking can also be a contributing factor to chronic kidney disease.

Often there are no outward signs in the earlier stages of chronic kidney disease, which is grouped into stages 1 through 5. Generally, earlier stages are known as 1 to 3. And as kidney disease progresses, you may notice the following symptoms. Nausea and vomiting, muscle cramps, loss of appetite, swelling via feet and ankles, dry, itchy skin, shortness of breath, trouble sleeping, urinating either too much or too little. However, these are usually in the later stages, but they can also happen in other disorders. So don't automatically interpret this as having kidney disease. But if you're experiencing anything that concerns you, you should make an appointment with your doctor.

Even before any symptoms appear, routine blood work can indicate that you might be in the early stages of chronic kidney disease. And the earlier it's detected, the easier it is to treat. This is why regular checkups with your doctor are important. If your doctor suspects the onset of chronic kidney disease, they may schedule a variety of other tests. They may also refer you to a kidney specialist, a nephrologist like myself. Urine tests can reveal abnormalities and give clues to the underlying cause of the chronic kidney disease. And this can also help to determine the underlying issues. Various imaging tests like ultrasounds or CT scans can be done to help your doctor assess the size, the structure, as well as evaluate the visible damage, inflammation or stones of your kidneys. And in some cases, a kidney biopsy may be necessary. And a small amount of tissue is taken with a needle and sent to the pathologist for further analysis.

Treatment is determined by what is causing your kidneys to not function normally. Treating the cause is key, leading to reduced complications and slowing progression of kidney disease. For example, getting better blood pressure control, improved sugar control and diabetes, and reducing weight are often key interventions. However, existing damage is not usually reversible. In some conditions, treatment can reverse the cause of the disease. So seeking medical review is really important. Individual complications vary, but treatment might include high blood pressure medication, diuretics to reduce fluid and swelling, supplements to relieve anemia, statins to lower cholesterol, or medications to protect your bones and prevent blood vessel calcification. A lower-protein diet may also be recommended. It reduces the amount of waste your kidneys need to filter from your blood. These can not only slow the damage of kidney disease, but make you feel better as well. When the damage has progressed to the point that 85 to 90 percent of your kidney function is gone, and they no longer work well enough to keep you alive, it's called end-stage kidney failure. But there are still options. There's dialysis, which uses a machine to filter the toxins and remove water from your body as your kidneys are no longer able to do this. Where possible, the preferred therapy is a kidney transplant. While an organ transplant can sound daunting, it's actually often the better alternative, and the closest thing to a cure, if you qualify for a kidney transplant.

If you have kidney disease, there are lifestyle choices. Namely quit smoking. Consuming alcohol in moderation. If you're overweight or obese, then try to lose weight. Staying active and getting exercise can help not only with your weight, but fatigue and stress. If your condition allows, keep up with your routine, whether that's working, hobbies, social activities, or other things you enjoy. It can be helpful to talk to someone you trust, a friend or relative who's good at listening. Or your doctor could also refer you to a therapist or social worker. It can also be helpful to find a support group and connect with people going through the same thing. Learning you have chronic kidney disease and learning how to live with it can be a challenge. But there are lots of ways to help you to be more comfortable for longer before more drastic measures are needed. And even then, there is plenty of hope. If you'd like to learn even more about chronic kidney disease, watch our other related videos or visit mayoclinic.org. We wish you well.

Chronic kidney disease happens when the kidneys are damaged for more than a few months. The kidneys clean the blood by removing waste and extra fluid, which leaves the body as urine. They help control blood pressure and balance salt and minerals. The kidneys also help the body make red blood cells and keep bones strong.

In the early stages of chronic kidney disease, you might not feel sick or have any symptoms. You might not know that you have kidney disease until the condition is advanced.

Healthcare professionals can find kidney disease through blood and urine tests. These tests look for high levels of waste in the blood or unusual things in the urine, such as protein or tiny amounts of blood. They also might use tests such as ultrasound or CT scans to look at the kidneys.

Treatment for chronic kidney disease aims to slow down damage to the kidneys. This often is done by managing the cause of the damage. But, even after a cause has been found and treated, kidney damage could still get worse. Chronic kidney disease can progress to end-stage kidney failure. This is fatal unless a person gets a kidney transplant or starts dialysis, a treatment that does the job of the kidneys.

Symptoms

Chronic kidney disease symptoms tend to develop slowly over time.

Loss of kidney function can cause a buildup of fluid or waste in the body. It also can cause acids, potassium and phosphate to build up in the blood.

Symptoms of kidney disease often are vague. Most people with kidney disease have no symptoms until the very last stages of kidney disease. This is known as advanced kidney disease.

When chronic kidney disease becomes advanced, loss of kidney function can cause:

  • Nausea.
  • Vomiting.
  • Loss of appetite.
  • Fatigue and weakness.
  • Sleep problems.
  • Decreased mental sharpness.
  • High blood pressure that's hard to manage.
  • Shortness of breath, if fluid builds up in the lungs.

Stages of kidney disease

There are five stages of kidney disease. To learn what stage you have, your healthcare team performs a blood test to check how well the kidneys are working. This blood test is called the estimated glomerular filtration rate (eGFR). The eGFR measures how much blood the kidneys filter each minute, recorded as milliliters per minute (mL/min). A low eGFR number means the kidneys are working less well.

When the kidneys no longer work at the level needed to keep a person alive, it's called end-stage kidney disease. This happens when you have an eGFR under 15.

As a part of kidney disease staging, your healthcare professional also might test whether you have protein in your urine.

Kidney disease stage eGFR, mL/min Kidney function
Stage 1 90 or above Healthy kidney function
Stage 2 60 to 89 Mild loss of kidney function
Stage 3a 45 to 59 Mild to moderate loss of kidney function
Stage 3b 30 to 44 Moderate to severe loss of kidney function
Stage 4 15 to 29 Severe loss of kidney function
Stage 5 Less than 15 Kidney failure
Source: National Kidney Foundation

When to see a doctor

If you have an ongoing health condition that raises your risk of kidney disease, your main healthcare professional may want to monitor the health of your kidneys. Having long-standing high blood pressure, diabetes or an autoimmune disease such as lupus can cause damage to the kidneys.

Regular checkups to monitor how well the kidneys are working may include blood tests and tests to check for protein in the urine. You may see your main healthcare professional every 6 to 12 months for these tests. If test results show possible kidney problems, you may be referred to a doctor who specializes in kidney diseases. This type of doctor is called a nephrologist.

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Causes

Chronic kidney disease happens when a disease or condition hurts kidney function. Often, chronic kidney disease has more than one cause.

Causes of chronic kidney disease include:

  • Type 1 or type 2 diabetes.
  • High blood pressure.
  • Some autoimmune diseases, such as lupus, sarcoidosis and Sjogren syndrome.
  • Polycystic kidney disease or other inherited kidney diseases.
  • Prolonged obstruction of the urinary tract, from conditions such as enlarged prostate or urinary tract tumors.
  • Vesicoureteral (ves-ih-koe-yoo-REE-tur-ul) reflux, a condition that causes urine to back up into the kidneys.
  • Certain medicines, such as lithium, large doses of ibuprofen or other nonsteroidal anti-inflammatory drugs, and drugs that suppress the immune system.

How kidneys work

One of the important jobs of the kidneys is to clean the blood. As blood moves through the body, it picks up extra fluid, chemicals and waste. The kidneys separate this material from the blood. It's carried out of the body in urine. If the kidneys are unable to do this and the condition is untreated, serious health problems result, with eventual loss of life.

Risk factors

Factors that can raise your risk of chronic kidney disease include:

  • Diabetes.
  • High blood pressure.
  • Heart disease.
  • Smoking.
  • Being overweight.
  • Being Black, Native American or Asian American.
  • Family history of kidney disease.
  • Changes or problems in the shape or size of the kidneys.
  • Older age.
  • Frequent use of medicines that can damage the kidneys.

Complications

Chronic kidney disease can affect almost every part of the body. Complications can include:

  • High blood pressure. Since the kidneys don't work as well to remove extra salt and water from the body, blood pressure starts to rise. High blood pressure can lead to more kidney damage, which in turn raises blood pressure even more.
  • Acid buildup. Also called acidosis, acid buildup happens when the kidney can't remove extra acids the body makes or you take in with the foods you eat. This can lead to issues with bone health and protein breakdown.
  • Fluid retention. This could lead to leg swelling, high blood pressure or fluid in the lungs, also called pulmonary edema, which causes shortness of breath. Fluid retention usually happens in later stages of kidney disease. A sudden increase in body weight might be a sign of fluid retention.
  • High blood potassium levels. Also called hyperkalemia, this condition may happen suddenly. It usually happens in the later stages of kidney disease and may damage the heart and be life-threatening.
  • Anemia. This happens when there aren't enough healthy red blood cells to carry oxygen to the body's tissues.
  • Heart disease. With advanced kidney disease, blood vessels called arteries can become stiff and get clogged. This makes blood pressure go up and could lead to heart disease.
  • Weak bones. Weak bones and a higher risk of bone fractures can happen.
  • Sexual health concerns. Lower sex drive, erectile dysfunction or reduced fertility can happen.
  • Damage to the central nervous system. This could lead to trouble concentrating or personality changes. This complication usually happens in the very last stages of kidney disease.
  • Immune system changes. You may have a lowered immune response, which puts you at risk of infection.
  • Pericarditis. This inflammation of the saclike membrane that covers the heart can happen in people with advanced kidney disease.
  • Pregnancy complications. The mother and the unborn baby may be at risk.
  • Lasting damage to the kidneys. Dialysis or a kidney transplant may be needed to survive.

Prevention

To lower the risk of developing kidney disease:

  • Follow instructions on medicines that you buy off the shelf. If you use an off-the-shelf pain reliever, such as ibuprofen (Advil, Motrin IB, others), it's important to follow the instructions on the package. Taking too many pain relievers for a long time could lead to kidney damage.
  • Keep a healthy weight. If you're at a healthy weight, being physically active most days of the week can help keep it that way. If you need to lose weight, talk with your healthcare team about a weight-loss plan.
  • Don't smoke. Cigarette smoking can hurt the kidneys and make existing kidney damage worse. If you smoke, talk to your healthcare team about ways to quit. Support groups, counseling and medicines can help you to stop.
  • Manage medical conditions with the help of your healthcare team. If you have diseases or conditions that raise your risk of kidney disease, work with your healthcare team to manage them. Ask about tests to look for signs of kidney damage. If you have high blood pressure, follow a low-sodium diet, check your blood pressure regularly at home and take any medicines you've been prescribed to lower your blood pressure. This can help protect your kidneys.

Dec. 09, 2025

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