IgA nephropathy (nuh-FROP-uh-thee), also known as Berger disease, is a kidney disease. It happens when a germ-fighting protein called immunoglobulin A (IgA) builds up in the kidneys. This causes a type of swelling called inflammation that, over time, can make it harder for the kidneys to filter waste from the blood.

IgA nephropathy often becomes worse slowly over years. But the course of the disease varies from person to person. Some people leak blood into their urine without having other problems. Others might have complications such as losing kidney function and spilling protein into the urine. Still others develop kidney failure, which means the kidneys stop working well enough to filter the body's waste on their own.

There's no cure for IgA nephropathy, but medicines can slow how quickly it becomes worse. Some people need treatment to lower inflammation, reduce the spilling of protein into the urine and prevent the kidneys from failing. Such treatments may help the disease become not active, a state called remission. Keeping blood pressure under control and lowering cholesterol also slow the disease.

IgA nephropathy often doesn't cause symptoms early on. You might not notice any health effects for 10 years or more. Sometimes, routine medical tests find signs of the disease, such as protein and red blood cells in the urine that are seen under a microscope.

When IgA nephropathy causes symptoms, they might include:

• Cola- or tea-colored urine caused by blood. You might notice these color changes after a cold, sore throat or respiratory infection.
• Blood that can be seen in the urine.
• Foamy urine from protein leaking into the urine. This is called proteinuria.
• Pain on one or both sides of the back below the ribs.
• Swelling in the hands and feet called edema.
• High blood pressure.
• Weakness and tiredness.

If the disease leads to kidney failure, symptoms may include:

• Rashes and itchy skin.
• Muscle cramps.
• Upset stomach and vomiting.
• Less appetite.
• Metallic taste in the mouth.
• Confusion.

Kidney failure is life-threatening without treatment. But dialysis or a kidney transplant can help people live for many more years.

When to see a doctor

See your doctor if you think you have symptoms of IgA nephropathy. It's key to get a checkup if you notice blood in your urine. Various conditions can cause this symptom. But if it keeps happening or it doesn't go away, it might be a sign of a serious health problem. Also see your doctor if you notice sudden swelling in your hands or feet.

The exact cause of IgA nephropathy is unknown. But these factors might raise the risk of getting it:

• Sex. In North America and Western Europe, IgA nephropathy affects at least twice as many men as it does women.
• Ethnicity. IgA nephropathy is more common in white people and people of Asian descent than it is in Black people.
• Age. IgA nephropathy most often develops between the mid-teens and mid-30s.
• Family history. IgA nephropathy appears to run in some families.

The course of IgA nephropathy varies from person to person. Some people have the disease for years with few or no problems. Many don't get diagnosed. Other people develop one or more of the following complications:

• High blood pressure. Damage to the kidneys from IgA buildup can raise blood pressure. And high blood pressure can do more damage to the kidneys.
• High cholesterol. High levels of cholesterol can raise the risk of a heart attack.
• Acute kidney failure. If the kidneys can't filter blood well enough due to buildup of IgA, levels of waste products rise quickly in the blood. And if kidney function gets worse very quickly, health care professionals may use the term rapidly progressive glomerulonephritis.
• Chronic kidney disease. IgA nephropathy can cause the kidneys to stop working over time. Then a treatment called dialysis or a kidney transplant is needed to live.
• Nephrotic syndrome. This is a group of problems that can be caused by damage to the glomeruli. The problems can include high urine protein levels, low blood protein levels, high cholesterol and lipids, and swelling of the eyelids, feet and stomach area.

You can't prevent IgA nephropathy. Talk with your doctor if you have a family history of the disease. Ask what you can do to keep your kidneys healthy. For example, it helps to lower high blood pressure and keep cholesterol at healthy levels.

IgA nephropathy is often found after you notice blood in your urine. Or a routine test might show that you have protein or blood in your urine. You'll need other exams too. They may include:

• Urine tests. A lab can check a sample of your urine under a microscope. This is done to find out how well your kidneys are working and how much protein the kidneys are spilling. With IgA nephropathy, the lab exam shows blood in the urine or other signs that could hint at inflammation of the tiny filters in the kidneys, called glomeruli.
• Blood tests. If you have kidney disease, blood tests might show higher levels of the waste product creatinine or the protein cystatin C.
• Kidney biopsy. This procedure is the only way to confirm whether you have IgA nephropathy. A special needle is used to take out small pieces of kidney tissue. Then the tissue is checked under a microscope.
• Iothalamate clearance test. Your doctor also may recommend this test. It uses a special contrast agent to track how well your kidneys are filtering wastes.

There's no cure for IgA nephropathy. There's also no sure way to predict how much the disease will affect your health over time. Some people need only medical tests to track whether the disease is getting worse.

For others, medicines can slow the disease from becoming worse and help manage symptoms.

Medicines to treat IgA nephropathy include:

• High blood pressure drugs. Medicines called angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) can lower blood pressure and reduce how much protein the body loses.
• Medicines that calm the immune system. These also are called immunosuppressants. They include corticosteroids and other strong medicines that can lessen the body's defenses. They might keep the immune system from making the proteins that attack the glomeruli. These medicines can cause serious side effects, such as high blood pressure, high blood sugar and a greater risk of infection. Your doctor helps you choose an immunosuppressant medicine. Many new treatments have been approved or are being tested in clinical trials. Talk with your doctor about the latest advances in the treatment of IgA nephropathy.
• Omega-3 fatty acids. These healthy fats might curb inflammation in the glomeruli without harmful side effects. You can get omega-3s from fish oil supplements. But don't buy those off the shelf. Ask your doctor if prescription fish oil supplements might help you.
• Cholesterol medicine. If you have high cholesterol, this type of medicine can help control it and slow down kidney damage.
• Diuretics. These can help control swelling in the hands and feet called edema.

The main goal of treatment is to keep you from needing dialysis or a kidney transplant. But either of those treatments can be lifesaving if your kidneys stop working well enough on their own.

To help keep your kidneys healthier:

• Take steps to lower your blood pressure. This can help slow kidney damage from IgA nephropathy. Start with some healthy lifestyle changes. Limit how much sodium and fat you eat. Lose any extra weight. Get regular exercise. And if you drink alcohol, do so in moderation. Also take your blood pressure medicines as prescribed.
• Keep track of your blood pressure at home. If your health care team asks you to do this, write down each blood pressure reading. Then bring the record with you to checkups.
• Eat less protein. Ask your doctor if you should cut back on protein. This may help slow IgA nephropathy from becoming worse and protect your kidneys.

Coping with severe forms of IgA nephropathy can be a challenge. But you don't have to do it alone. If you have questions or you need guidance, talk with a member of your health care team.

It also might help to join a support group. You can meet other people who may understand what you're going through and share information with you. To find out about support groups in your area that deal with kidney disease, ask your health care team. Or contact the National Kidney Foundation (NKF) to learn about NKF Peers, a national, telephone-based peer support program. Call 855-NKF-PEER (855-653-7337) to join.

You're likely to start by seeing your primary doctor. But you might be referred to a doctor who is trained to treat kidney disorders, called a nephrologist. Here are some tips to get ready for your appointment.

What you can do

Ask your doctor's office if you need to fast for a blood test or follow any other restrictions.

Make a list of:

• Your symptoms and when they began. Include any symptoms that don't seem related to the reason for your appointment.
• All medicines you take. Include medicines you buy without a prescription, vitamins, herbs or other supplements. Note how much medicine you take, called the dose.
• Questions to ask your doctor. This way you can make the most of your time together.

Ask a family member or friend to go with you to help you remember the information you receive.

Questions to ask your doctor include:

• What tests do I need?
• What's the best course of action? How long will I need medicines?
• Can I manage this disease with diet and lifestyle changes?
• I have other health conditions. How can I best manage these conditions together?
• Do you have printed materials on this condition that I can have? What websites do you recommend?

What to expect from your doctor

Your doctor is likely to ask you questions such as:

• Do your symptoms happen often or just once in a while?
• How bad are your symptoms?
• Does anything seem to make them better?
• What, if anything, seems to make them worse?