IgA nephropathy is a kidney disease where a protein called immunoglobulin A builds up in the kidneys’ filtering units, causing inflammation and potential damage over time. While there’s no cure yet, new treatment options and lifestyle changes can help many people manage the disease and maintain their kidney function for years.

Understanding IgA Nephropathy

IgA nephropathy, also known as Berger disease, happens when a specific protein called immunoglobulin A or IgA accumulates in the tiny blood vessels inside your kidneys. These blood vessels, called glomeruli, act like filters that clean waste from your blood. When IgA clumps together and gets stuck in these filters, it causes swelling and inflammation that can make it harder for your kidneys to do their job properly.^[2] The damage doesn’t happen overnight—it develops slowly, often over many years, which is why some people don’t realize they have the condition until it’s found during routine medical testing.^[3]

This disease got its name from the two French doctors, Jean Berger and Nicole Hinglais, who first identified it in the late 1960s.^[4] Since then, researchers have learned much more about how it affects the body, though many questions remain about why it develops in the first place.

Epidemiology: How Common Is IgA Nephropathy?

IgA nephropathy stands as the most common form of glomerulonephritis, which is inflammation of the kidney’s filtering units, affecting people around the world.^[5] However, the disease doesn’t affect all populations equally. The global incidence is approximately 2.5 cases per 100,000 people each year among adults.^[7] When looking at kidney biopsies—a procedure where doctors examine a small piece of kidney tissue under a microscope—the frequency of IgA nephropathy varies significantly by region.^[3]

In the United States, about 1 out of every 10 kidney biopsies show IgA nephropathy. The numbers are much higher in East Asian countries, where IgA nephropathy appears in about 4 out of every 10 kidney biopsies. In European countries, it shows up in between 2 and 3 out of every 10 biopsies.^[4] These geographic differences suggest that genetics and ethnicity play important roles in who develops the disease.

IgA nephropathy can affect people at any age, but it’s most commonly diagnosed in young and middle-aged adults, particularly those in their late teens to late 30s.^[4] The disease appears more frequently in men than in women.^[4] Some studies suggest that certain racial and ethnic groups may be at higher risk, though the disease can affect people of any background.

What Causes IgA Nephropathy?

The exact cause of IgA nephropathy remains largely a mystery to medical researchers, though significant progress has been made in understanding how it develops. Scientists believe that IgA nephropathy is an autoimmune disease, which means the body’s immune system—normally designed to protect against infections—mistakenly attacks its own tissues.^[3]

In people with IgA nephropathy, something goes wrong with how the body produces IgA antibodies. These antibodies normally help fight off germs like bacteria and viruses. However, in IgA nephropathy, the body makes IgA molecules that have less galactose, which is a type of sugar that should be attached to these proteins. The immune system sees these abnormal IgA molecules as foreign invaders and sends other antibodies to attack them.^[4]

When these antibodies bind together with the abnormal IgA, they form clusters called immune complexes. These clumps travel through the bloodstream and eventually get trapped in the glomeruli of the kidneys. Once stuck there, they trigger inflammation and damage the delicate filtering structures.^[4] Over time, this ongoing inflammation can lead to scarring of the kidney tissue, making it less effective at filtering waste from the blood.

Researchers have also noticed that some people experience flare-ups of their symptoms after having a cold or upper respiratory infection. During these infections, the body produces more IgA immune complexes, and more of these complexes end up depositing in the kidneys, which can worsen the damage.^[4]

Risk Factors for Developing IgA Nephropathy

Several factors can increase a person’s likelihood of developing IgA nephropathy. Understanding these risk factors can help people and their doctors stay alert for early signs of the disease.

A family history of IgA nephropathy or a related condition called IgA vasculitis, formerly known as Henoch-Schönlein purpura, increases the risk of developing the disease.^[4] This suggests that genetics play a role, and researchers have identified some genetic markers that may be associated with increased susceptibility. However, having these genetic factors doesn’t guarantee someone will develop the disease—it just means they have a higher chance.

Being male increases the risk, as IgA nephropathy affects men more often than women.^[4] Age is another factor, with most diagnoses occurring in people in their late teens through late 30s, though the disease can develop at any age.

Geographic and ethnic background also matter. People of Asian and European descent appear to have higher rates of IgA nephropathy compared to other ethnic groups.^[4] Some research suggests that obesity may cause the disease to progress more quickly once it develops.^[12]

Various systemic diseases can be associated with IgA nephropathy as well. These include liver failure, certain cancers, celiac disease (an autoimmune disorder triggered by gluten), systemic lupus erythematosus, rheumatoid arthritis, heart failure, and HIV infection.^[5]

Recognizing the Symptoms

One of the most challenging aspects of IgA nephropathy is that it often develops silently. Many people don’t experience any noticeable symptoms in the early stages, and the disease can progress quietly for years or even decades without causing obvious health problems.^[2] In fact, up to 40% of people with IgA nephropathy show no recognizable symptoms when they’re first diagnosed.^[13] This is why routine medical testing is so important—it can catch signs of the disease before symptoms appear.

When symptoms do occur, the most common and classic presentation involves blood in the urine, called hematuria. In 40-50% of cases, people notice that their urine has turned a cola or tea color, especially within a day or two after having a cold, sore throat, or respiratory infection.^[5] This happens because the infection triggers the body to produce more of the problematic IgA immune complexes, which then deposit in the kidneys and cause bleeding into the urine. This distinctive pattern—blood in the urine following an infection—is different from other types of kidney disease and can be an important clue for doctors.

Some people have microscopic amounts of blood in their urine that can only be seen under a microscope during laboratory testing. They may never notice any color changes themselves, which is why regular check-ups that include urine testing are valuable.^[5]

Another common symptom is proteinuria, which means protein is leaking into the urine. This can make the urine appear foamy or bubbly, like soap suds. Protein normally stays in the blood, but when the kidneys’ filters are damaged, protein can slip through. This is often one of the first laboratory signs that something is wrong with the kidneys.^[4]

Many people with IgA nephropathy develop high blood pressure, also called hypertension. This happens because damaged kidneys can’t regulate the body’s fluid and salt balance as well as they should.^[2] High blood pressure can be both a symptom and a complication of IgA nephropathy, creating a cycle where kidney damage leads to high blood pressure, which in turn causes more kidney damage.

Swelling, called edema, can occur in various parts of the body, particularly in the face, around the eyes, and in the lower legs, ankles, and feet. This happens when the kidneys can’t remove extra fluid from the body effectively, causing it to build up in the tissues.^[4] Some people also experience pain in their sides or lower back, in the area where the kidneys are located. This pain is sometimes called flank pain.

As the disease progresses and kidney function declines, other symptoms may develop, including fatigue, joint pain, high cholesterol levels, and weight gain from fluid retention.^[13] In more advanced cases where kidney function is significantly reduced, people might experience symptoms related to kidney failure, such as nausea, loss of appetite, itching, and confusion.

Prevention Strategies

Because the exact cause of IgA nephropathy isn’t fully understood, there’s currently no known way to prevent the disease from developing in the first place. However, once diagnosed, there are many important steps people can take to slow the disease’s progression and prevent complications.

One of the most crucial preventive measures is controlling blood pressure. Keeping blood pressure at healthy levels helps protect the kidneys from further damage and reduces the risk of the disease progressing to kidney failure. This typically involves both medications and lifestyle changes like reducing salt intake, maintaining a healthy weight, exercising regularly, limiting alcohol consumption, and avoiding tobacco products.^[9]

Following a kidney-friendly diet is another important preventive strategy. This typically means limiting sodium intake to help control blood pressure and reduce swelling. Many doctors recommend keeping sodium intake well below the standard guideline of 2 grams per day, though the specific recommendation should come from your healthcare team based on your individual situation.^[12] A dietitian who specializes in kidney disease can help create a personalized eating plan.

Staying at a healthy weight is important, as research suggests that obesity may accelerate the progression of IgA nephropathy.^[12] Regular physical activity not only helps with weight management but also supports overall kidney health and helps control blood pressure.

For people with a family history of IgA nephropathy or other risk factors, regular screening through simple urine and blood tests can help detect the disease early, when interventions are most effective. Even if you feel perfectly healthy, these routine tests can catch microscopic blood or protein in the urine before any symptoms appear.

Managing stress and prioritizing mental health is also valuable. The connection between mental well-being and physical health is strong, and stress can affect blood pressure and overall health. Finding healthy ways to cope with stress, whether through exercise, meditation, hobbies, or talking with a counselor, can be beneficial.^[12]

Avoiding tobacco products and limiting alcohol consumption are universally recommended for kidney health. Smoking can damage blood vessels throughout the body, including in the kidneys, and can raise blood pressure. If you smoke, quitting is one of the best things you can do for your kidney health.^[12]

How IgA Nephropathy Changes Body Function

To understand how IgA nephropathy affects the body, it helps to know what healthy kidneys do. Your kidneys are bean-shaped organs about the size of your fist, located on either side of your spine in your lower back. They work around the clock performing several vital jobs: filtering waste products and excess fluid from your blood to make urine, regulating blood pressure, maintaining the balance of minerals and electrolytes in your body, and producing hormones that help make red blood cells.

The kidneys contain about a million tiny filtering units called nephrons. Each nephron contains a cluster of blood vessels called a glomerulus, which acts like a strainer. As blood flows through the glomeruli, they filter out waste products, excess water, and other substances while keeping important things like proteins and blood cells in the bloodstream. The filtered waste becomes urine, which travels down tubes called ureters to the bladder.

In IgA nephropathy, this filtering process becomes damaged through a series of events. The abnormal IgA immune complexes deposit in the glomeruli, where they trigger an inflammatory response. The immune system sends cells to the area to deal with what it perceives as a threat, and this immune response causes swelling and inflammation in the delicate glomerular tissue.^[2]

This inflammation damages the glomeruli’s filtering membranes, making them more permeable than they should be. As a result, things that should stay in the blood—like red blood cells and proteins—start leaking through into the urine. This is why blood and protein in the urine are hallmark signs of the disease. The filtering membranes become less selective, unable to properly distinguish between what should be filtered out and what should stay in the blood.

Over time, the ongoing inflammation leads to scarring of the glomeruli and surrounding tissue, a process called fibrosis. Scarred kidney tissue is stiff and non-functional—it can’t filter blood effectively. As more and more nephrons become scarred and stop working, the kidney’s overall filtering capacity, measured as the glomerular filtration rate or GFR, gradually declines.^[3]

The damaged kidneys also lose their ability to regulate blood pressure properly. Healthy kidneys help control blood pressure by managing the body’s fluid volume and producing hormones that affect blood vessels. When kidneys are damaged, they may retain too much salt and water, increasing blood volume and raising blood pressure. They may also produce hormones that constrict blood vessels, further elevating blood pressure.^[4]

As kidney function declines, waste products that should be filtered out start building up in the blood. This can lead to a condition called uremia, where high levels of waste products affect how the body functions, causing fatigue, nausea, confusion, and other symptoms. The kidneys’ role in producing a hormone called erythropoietin, which stimulates red blood cell production, may also be impaired, leading to anemia and fatigue.

The disease doesn’t affect everyone the same way or progress at the same rate. Some people maintain relatively stable kidney function for many years, while others experience a gradual decline over decades. Unfortunately, without treatment, about 25-30% of people with IgA nephropathy will develop chronic kidney failure within 20 years.^[5] However, with proper treatment and management, many people can slow this progression significantly and maintain good kidney function for much longer.

Recent research has revealed that even people with lower levels of protein in their urine are at risk of disease progression, which has increased the urgency for early and proactive treatment.^[13] The traditional approach of “watching and waiting” is being replaced by more active treatment strategies aimed at preventing irreversible kidney damage before it occurs.