Understanding IgA nephropathy (Berger's disease)

IgA nephropathy (IgAN), also called Berger's disease, occurs when an antibody called immunoglobulin A (IgA) builds up in the kidneys. This lowers the kidney's ability to remove waste, excess salt and water from the body.

IgA nephropathy usually progresses slowly over many years. However, the severity of the disease varies from person to person. For example, some people show symptoms of the disease but don't develop any health problems, while others develop kidney disease or kidney failure.

Antibodies are proteins made by the immune system to fight bacteria, viruses and toxins. IgA is one of the most common antibodies in the human body and plays a vital role in keeping you healthy. But in IgA nephropathy, this antibody builds ups and forms clumps in the glomeruli, the tiny blood vessels in the kidneys that filter the blood. Over time, this causes inflammation and damages the kidneys.

IgA nephropathy usually doesn't cause symptoms in the early stages, so it can go unnoticed for years or decades. The disease is sometimes suspected when a routine urine test reveals red blood cells in the urine that can only be seen with a microscope.

Signs and symptoms of IgA nephropathy include:

• Cola- or tea-colored urine — caused by red blood cells in the urine.
• Visible blood in the urine or urine that's the color of tea or cola after strenuous exercise or after you've had a cold or other respiratory infection.
• Urine that looks foamy or bubbly, which might indicate high levels of protein in the urine.
• Swelling in your hands and feet.
• High blood pressure.
• Pain in one or both sides of your back below your ribs.

When kidney disease is more advanced, signs and symptoms can include loss of appetite, fatigue, nausea, vomiting, itchiness, a metallic taste, confusion or problems thinking. Signs that fluid is building up in the body include difficulties breathing during activity or while at rest, an increase in water weight, and swelling in the lower parts of the body.

Researchers don't know what causes the IgA antibody to start collecting in the kidneys. There is a genetic connection because the disease runs in families and is more common in some ethnic groups. However, most cases occur in people with no family history of the disease.

People with certain health conditions have a higher chance of developing IgAN, including:

• Liver diseases. These include cirrhosis and chronic hepatitis B and C infections.
• Celiac disease. Eating gluten, a protein found in most grains, triggers this digestive condition.
• Infections. These include HIV and some bacterial infections.

There's no cure for IgA nephropathy and no sure way to predict if the disease will become severe or not. But with the right treatment, people can keep their kidneys as healthy as possible and slow down the pace at which the disease develops.

Treatments and lifestyle changes to slow the process of kidney damage include:

• High blood pressure medications. Taking angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) can lower blood pressure and reduce protein loss.
• Omega-3 fatty acids. These fats, available in dietary fish oil supplements, might reduce inflammation in the glomeruli without harmful side effects. Talk to your health care provider before you start supplements.
• Immunosuppressants. These medications calm the immune system and stop it from attacking the glomeruli. These include glucocorticosteroids, mycophenolate mofetil, targeted-release budesonide and others.
• Statin therapy. If you have high cholesterol, cholesterol-lowering medications can help control it and slow the progression of kidney damage.
• Diuretics. These remove extra fluid from the blood. Removing extra fluid can help improve blood pressure control.
• Novel therapies. New therapies such as SGLT2 inhibitors and sparsentan are approved or being considered to treat IgA nephropathy. There is current research and heightened interest in using medicines that inhibit the complement system to effectively treat IgA nephropathy.
• Lifestyle changes. Your health care team may recommend losing excess weight, being physically active, drinking alcohol only in moderation and not smoking to slow the rate of damage to your kidneys.
• Diet changes. Reducing salt (sodium), eating less protein and following a heart-healthy diet can help decrease the burden on the kidneys.

The goal of treatment is to avoid the need for kidney dialysis or a kidney transplant. But in some cases, dialysis or transplantation is necessary.