Getting a diagnosis of immunoglobulin A nephropathy — also known as IgA nephropathy or Berger disease — can bring up a lot of questions. Some of the first might be related to your kidney health, treatment options, and what to expect next. But did you know there are multiple types of IgA nephropathy, too?

In this article, we’ll discuss the three main types of IgA nephropathy (IgAN): primary, secondary, and IgA-associated. Each type begins differently, but all of them can affect the kidney filters — also called glomeruli. We’ll explain how IgA (an immune protein) can build up in the kidneys and lead to inflammation. Finally, we’ll share what to know about the symptoms, diagnosis, and treatment for each type.

What Is IgA Nephropathy?

IgA nephropathy is a kidney disease affecting the glomeruli, or kidney filters. Their job is to remove waste and extra fluid from the blood. In IgAN, a protein made by the immune system — called immunoglobulin A (IgA) — builds up in these filters. This buildup causes swelling and irritation, among other problems, and can damage the kidneys over time.

IgA is one of the body’s main antibodies — proteins that, under normal conditions, help protect you from illness. Most IgA lives in areas like the nose, throat, and gut. But in IgAN, the body makes a slightly different form of IgA. Because of this, the immune system reacts to it. The IgA protein and other antibodies can join together and form immune complexes. These complexes travel through the bloodstream and get trapped in the glomeruli, where they cause irritation and kidney damage.

Some people with IgAN have no symptoms at first. Others may develop symptoms, including:

• Blood in the urine
• Proteinuria (Protein in the urine)
• Hypertension (high blood pressure) or edema (swelling)

To receive a diagnosis, your doctor will ask about your family and medical history and order blood and urine tests. The only way to confirm IgAN is with a kidney biopsy, where a small piece of tissue is removed and checked for deposits of IgA.

The Three Types of IgA Nephropathy

Even though all forms of IgA nephropathy involve IgA building up in the glomeruli, the reason this buildup happens can differ. The different types of nephropathy describe where the problem starts and whether another condition is involved.

All three forms show IgA deposits in the mesangium (support tissue inside the glomerulus). This can lead to inflammation, changes in kidney function, and other symptoms. In the sections below, we’ll break down each type and explain how it develops, what symptoms may appear, and how doctors diagnose and manage it.

1. Primary IgA Nephropathy

Primary IgA nephropathy is the most common form of the condition. In this type, IgA buildup starts inside the kidney, without another illness setting it off. Because of this, primary IgAN is often considered a primary glomerular disease, meaning the kidneys are the first place where the problem begins.

How It Develops

Doctors now explain primary IgAN using what’s called the “four-hit” model. First, the body makes too much galactose-deficient IgA1 — a form of IgA1 that is shaped differently and is mostly made in the nose and gut. Next, the immune system creates autoantibodies (antibodies that mistakenly target the body’s own tissues) that attach to this altered IgA1. The final step occurs when these antibody complexes settle in the kidney’s mesangium. This triggers inflammation and signals the cells in this area to release chemicals called cytokines that cause irritation and injury to the glomeruli over time.

Signs and Symptoms of Primary IgAN

Many people with IgAN feel healthy for years. Early changes may only be found during routine tests that show blood or protein in the urine. When IgAN symptoms do appear, they may include:

• Dark or tea-colored urine, sometimes after a cold or infection
• Foamy urine as a result of protein loss
• Swelling in the hands, feet, or face
• Back or side pain (flank pain)
• High blood pressure
• Unusual tiredness or weakness (fatigue)

Diagnosis and Monitoring

Primary IgAN is confirmed with a kidney biopsy, where a small tissue sample is checked using immunofluorescence. This test uses special dyes to show IgA deposits under a microscope. Doctors may also monitor renal (kidney) health with:

• Serum creatinine (a blood test that reflects renal function)
• Glomerular filtration rate (GFR), which measures how well the kidneys filter waste
• Urinalysis (urine test) to check for blood and protein

Treating Primary IgA Nephropathy

Treatment for IgA nephropathy focuses on protecting the kidneys and slowing inflammation. Examples of medications include:

• Angiotensin-converting enzyme (ACE) inhibitors or angiotensin-receptor blockers to relax blood vessels and lower protein in the urine.
• Corticosteroids or other drugs that calm the immune system, such as budesonide
• Medications that lower the amount of protein in your urine, such as SGLT2 inhibitors and endothelin receptor antagonists
• Complement inhibitors that target your immune system

2. Secondary IgA Nephropathy

Unlike primary IgAN, which begins inside the kidneys themselves, secondary IgAN starts with a separate condition that affects the immune system’s ability to clear IgA. These related conditions can increase the amount of IgA in the blood or change how IgA is processed.

What Triggers Secondary IgAN?

Many different conditions can place extra stress on the immune system or liver, which may allow IgA-containing immune complexes to circulate longer and reach the kidneys. Some of the most common triggers include:

• Liver disease, especially cirrhosis (liver scarring)
• Inflammatory bowel diseases, such as Crohn’s or ulcerative colitis
• Chronic (long-term) bacterial or viral conditions
• Autoimmune diseases, such as lupus or psoriasis
• Celiac disease
• Certain blood cancers or immune disorders

Symptoms, Diagnosis, and Treatment of Secondary IgAN

Secondary IgAN often looks similar to primary IgAN, with signs like blood or protein in the urine, swelling, and rising blood pressure. However, symptoms may appear alongside the underlying condition, such as liver diseases, chronic infection, or an autoimmune disease flare-up. A kidney biopsy is still used to confirm the diagnosis, but doctors may also look for clues that another illness is driving the IgA deposits.

Supportive care, including blood pressure control and lower proteinuria, is still important. However, the first priority is often treating the condition causing the kidney inflammation. For example, managing cirrhosis, clearing a chronic infection, or treating autoimmune activity can reduce IgA buildup and help stabilize kidney function. Some cases improve significantly once the trigger is addressed.

3. IgA-Associated Nephropathy

IgA-associated nephropathy is a broader category that includes conditions where IgA affects both the kidneys and other organs. The most well-known example is IgA vasculitis, formerly called Henoch-Schönlein purpura. In this condition, IgA deposits collect not only in the glomeruli but also in small blood vessels throughout the body.

How It Develops

In IgA vasculitis, IgA deposits settle not just in the kidneys but also in blood vessels in the skin, intestines, organs, and joints. Unlike primary IgAN, IgA-associated nephropathy begins as a systemic condition, meaning symptoms often appear outside the kidneys before any urine changes develop. Many children recover fully, but adults are more likely to develop more serious complications with lasting kidney problems.

Signs and Symptoms of IgA-Associated Nephropathy

Since IgA-associated nephropathy can affect several body systems at once, symptoms may differ from primary and secondary forms of IgAN. Common symptoms may include:

• Purplish rash (purpura) on the legs, feet, or buttocks
• Swollen, painful joints
• Abdominal (belly) pain, nausea, or vomiting
• Dark or bloody stools
• Blood or protein in the urine

Diagnosis and Treatment

IgA-associated nephropathy may be diagnosed based on rash, as well as joint and stomach symptoms. Blood and urine tests can help rule out other illnesses and check kidney function. Sometimes, a skin biopsy can be done to look for IgA deposits. If kidney problems are more serious, a kidney biopsy may be needed, too.

Most cases improve on their own with rest and fluids. For pain control, acetaminophen is preferred; nonsteroidal anti-inflammatory drugs (NSAIDs) should be avoided when kidney involvement is present. If symptoms are severe, corticosteroids may help reduce pain and swelling. Rare complications, such as bowel blockage, may require surgery.

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On myIgANteam, people share their experiences with IgA nephropathy, get advice, and find support from others who understand. What type of IgAN do you have? What has your experience been like?