IgA nephropathy, also known as Berger’s disease, is a long-term kidney condition in which an antibody called immunoglobulin A builds up in the tiny filters of the kidneys and triggers inflammation. It is one of the most common causes of primary glomerulonephritis worldwide, yet many people carry it for years without symptoms, discovering it only when a routine urine test shows blood or protein. Because the kidneys can lose function slowly and silently, understanding this disease early makes a real difference. In this article you’ll learn what IgA nephropathy is, why it develops, the symptoms and lab tests that point to it, how doctors confirm the diagnosis, and the treatments, including several new options, that now help protect kidney function.
What is IgA nephropathy (Berger’s disease)?
IgA nephropathy is a disease of the glomeruli, the roughly one million microscopic filtering units in each kidney that clean waste and extra fluid from the blood. In this condition, an abnormal form of immunoglobulin A (IgA), an antibody the immune system normally uses to protect the lining of the gut and airways, clumps together and settles in the glomeruli. These deposits set off inflammation that, over time, can scar the filters and reduce how well the kidneys work. A 2026 review in JAMA describes IgA nephropathy as one of the most common primary glomerular diseases worldwide and an important cause of kidney failure in younger adults, which is part of why timely recognition matters so much.
The disease was first described by French physician Jean Berger in 1968, which is why it is still called Berger’s disease. The National Institute of Diabetes and Digestive and Kidney Diseases classifies it as an autoimmune kidney disease, meaning the immune system mistakenly damages the body’s own tissue.
How the disease affects the kidney’s filters
Researchers often describe IgA nephropathy as a step-by-step process sometimes called the four-hit model: the body makes a poorly formed version of IgA, the immune system produces antibodies against it, these join into larger clumps known as immune complexes, and the clumps lodge in the glomeruli and drive inflammation. The result is that blood and protein, which healthy filters keep in the bloodstream, begin to leak into the urine. This leakage is the reason the disease is usually first spotted on a urine sample rather than through obvious illness.
What causes IgA nephropathy?
There is rarely a single cause. IgA nephropathy develops from a mix of inherited tendency and immune triggers. Some families carry genes that make abnormal IgA more likely, which is why the disease occasionally runs in relatives. The gut’s immune system also appears central, because flare-ups of visible blood in the urine often follow infections of the throat, sinuses, or intestines.
Doctors separate the disease into primary IgA nephropathy, where it appears on its own, and secondary forms linked to other conditions such as celiac disease, chronic liver disease, or inflammatory bowel disease. A closely related condition, IgA vasculitis (formerly Henoch-Schonlein purpura), involves the same type of IgA deposits but also affects the skin, joints, and gut.
Who is most at risk
- Age: it is most often diagnosed in the late teens through the thirties, though it can appear at any age.
- Sex: in many regions it is diagnosed more often in men than in women.
- Ancestry: it is reported more frequently in people of East Asian and European descent and is less common in people of African ancestry.
- Family history: having a close relative with a glomerular disease raises the risk.
Symptoms and early signs
For many people, IgA nephropathy causes no symptoms at all, which is why it is sometimes found by chance during a check-up or an insurance or pregnancy screening. When signs do appear, they usually reflect blood and protein escaping through the damaged filters.
The most recognizable sign is visible blood that can turn the urine pink, red, or cola-colored, often within a day or two of a cold or sore throat. More commonly, a routine urine test detects microscopic blood in the urine. When the filters leak more heavily, the same test can reveal proteína en la orina, which may make it look foamy, and some people notice swelling in the legs, ankles, or around the eyes. Heavy, sustained protein loss can also cause low albumin in the blood, which contributes to that swelling. Rising blood pressure is another frequent and important clue.
Cuándo consultar a tu médico
Contact a health professional if you notice any of the following, especially if they persist:
- Urine that looks pink, red, brown, or cola-colored.
- Urine that stays foamy or bubbly from one day to the next.
- New swelling in the ankles, feet, hands, or face.
- Blood-pressure readings that are repeatedly high.
- Unusual tiredness or a drop in the amount of urine you pass.
These signs do not confirm IgA nephropathy on their own, but they are worth checking, because early evaluation gives the kidneys the best chance of protection.
How is IgA nephropathy diagnosed?
Diagnosis usually starts with simple, widely available tests and moves toward a kidney biopsy when the picture is unclear. The first step is often a urinalysis, and many patients find it useful to review a full urinalysis interpretation guide. The lab checks the sample for red blood cells and for protein, the two findings that most often raise suspicion.
Under the microscope, a technician may also spot red blood cell casts, tiny cylinders that form when bleeding comes from the filters themselves rather than the bladder. To measure protein loss, the lab reports a urine protein-to-creatinine ratio, and it also measures the creatinine found in the urine. A single blood draw can cover a full panel de función renal and check circulating immunoglobulin A antibodies, although a normal IgA result does not rule the disease out.
Doctors also measure and monitor presión arterial alta, and they rule out other causes of blood in the urine. They first exclude a common infección de vías urinarias, and a urinalysis can also flag white blood cells in the urine that point to infection instead. The only way to confirm IgA nephropathy for certain is a kidney biopsy, in which a doctor removes a tiny piece of kidney tissue and examines it for IgA deposits. Biopsy findings are graded with a standard system (known as MEST-C) that helps predict how the disease may behave.
What the key tests reveal
| Prueba | What it evaluates | Lo que puede indicar un resultado anormal |
|---|---|---|
| Urinalysis for blood (hematuria) | Red blood cells in the urine, visible or microscopic | Irritation or bleeding from the kidney’s filters, a hallmark of IgA nephropathy |
| Urine protein-to-creatinine ratio | How much protein leaks into the urine in a single sample | Higher values point to more filter damage and a greater risk of progression |
| Serum creatinine and eGFR | How well the kidneys clear waste from the blood | A rising creatinine or falling eGFR suggests reduced kidney function |
| Blood pressure | The pressure inside blood vessels, including those in the kidney | Persistently high readings can both result from and worsen kidney damage |
Treatment and newer therapies
There is no single cure for IgA nephropathy, but treatment has advanced quickly, and the goal is clear: lower the amount of protein in the urine, control blood pressure, and preserve kidney function for as long as possible. Care is tailored to how much protein a person loses and how fast their kidney function is changing.
Foundational care for everyone
- Blood-pressure control, because keeping blood pressure in a healthy range protects the filters. This starts with managing high blood pressure through medication and lifestyle.
- RAS blockade with ACE inhibitors or ARBs, medicines that lower blood pressure and, importantly, cut protein leakage.
- SGLT2 inhibitors, a group of drugs first developed for diabetes that are now used to slow the progression of many chronic kidney diseases.
- Everyday measures such as a lower-salt diet, not smoking, staying active, and reaching a healthy weight.
Targeted and disease-specific options
When protein loss stays high despite foundational care, doctors may add treatments aimed more directly at the immune process. A targeted-release form of the steroid budesonide (sold as Tarpeyo) is designed to act on the part of the gut where the faulty IgA is made. In selected cases, other immune-focused therapies and, historically, broader corticosteroids may be considered, always weighing benefits against side effects. The next section looks at the newest of these options and what current research shows.
Latest scientific advances in IgA nephropathy
The last few years have transformed the outlook for IgA nephropathy, moving care beyond blood-pressure control alone toward treatments that target the disease at its source. The summaries below translate recent trial findings into plain language, with a note on what each may mean for patients. These are research results, not personal medical advice, and your nephrologist can explain what fits your situation.
A gut-targeted steroid
What researchers found: in a phase 3 trial called NefIgArd, a targeted-release form of budesonide, a capsule built to release medicine where the abnormal IgA is produced, helped protect kidney function over two years compared with standard care. What this means for you: it offers a way to calm the disease at its likely starting point in the gut, with less of the body-wide effect of older steroids.
Medicines that ease pressure inside the filters
What researchers found: a class of drugs called endothelin receptor antagonists relaxes blood vessels in the kidney and reduces protein leakage. In a phase 3 trial, the drug atrasentan lowered protein in the urine in people already on standard treatment. What this means for you: less protein in the urine is one of the clearest signs that the kidneys are being better protected.
Calming the immune complement system
What researchers found: part of the immune system called the complement pathway helps drive the inflammation in IgA nephropathy. In a phase 3 trial, the complement inhibitor iptacopan reduced protein in the urine. What this means for you: it is a more targeted way to quiet one specific arm of the immune attack rather than suppressing immunity broadly.
Turning down the faulty antibody at its source
What researchers found: newer medicines aim at signaling proteins (known as APRIL and BAFF) that tell the body to make the abnormal IgA. An interim analysis of a phase 3 trial of sibeprenlimab, reported in 2025, showed reduced protein in the urine. What this means for you: these treatments try to address the root cause, though the approach is still being confirmed in longer studies.
Broader kidney protection and a new treatment paradigm
Kidney specialists increasingly combine several of these tools, and reviews published in 2025 describe a shift toward earlier, layered treatment that pairs foundational care such as SGLT2 inhibitors with disease-specific drugs. Research is moving fast: additional agents are being tested in active studies, including a recruiting trial of felzartamab (called PREVAIL) and an ongoing phase 3 program for sibeprenlimab (VISIONARY). If you are interested, ask your kidney doctor whether a clinical trial might be an option for you.
Outlook, monitoring, and living with IgA nephropathy
The course of IgA nephropathy varies widely. Many people keep stable kidney function for decades, while a smaller number progress toward kidney failure over the years. The strongest clues to the outlook are how much protein appears in the urine, whether blood pressure is controlled, and how kidney function measured by eGFR changes over time. Doctors weigh these factors together rather than relying on any single test, and they reassess them at each visit so that meaningful changes are caught early.
Staying ahead of the disease
Because the disease can be quiet, regular monitoring matters more than dramatic symptoms. Most people are followed with periodic urine and blood tests to track protein, creatinine, and eGFR, along with home or clinic blood-pressure checks. Reviewing these numbers as a trend, rather than reacting to a single result, gives the clearest picture of kidney health.
Everyday steps that help
- Take blood-pressure and kidney-protecting medicines as prescribed, even when you feel well.
- Keep dietary salt modest, and ask whether your protein intake needs any adjustment.
- Avoid regular use of anti-inflammatory painkillers (NSAIDs) unless your doctor approves them.
- Treat throat and other infections promptly, and keep up with recommended vaccinations.
- Bring your test results to appointments so you and your care team can watch the trend together.
Glosario de términos clave
| Término | Definición |
|---|---|
| Nefropatía por IgA | Also called Berger’s disease; a kidney disease in which the antibody immunoglobulin A builds up in the kidney’s filters and causes inflammation. |
| Inmunoglobulina A (IgA) | An antibody made by the immune system that normally helps defend the lining of the gut and airways. |
| Glomerulus (plural glomeruli) | One of about a million tiny filtering units in each kidney that clean the blood and form urine. |
| Hematuria | Blood in the urine, which may be visible (red or cola-colored) or microscopic (seen only under a microscope). |
| Proteinuria | Protein in the urine, often making it look foamy, and a sign that the filters are leaking. |
| TFGe (tasa de filtración glomerular estimada) | A number calculated from a blood creatinine test that estimates how well the kidneys filter. |
| Creatinina | A waste product from muscles that healthy kidneys remove; blood levels rise when filtering slows. |
| Kidney biopsy | A procedure that removes a tiny piece of kidney tissue so it can be examined under a microscope to confirm the diagnosis. |
| RAS blockade (ACE inhibitors and ARBs) | Blood-pressure medicines that also lower protein in the urine and help protect the kidneys. |
| Enfermedad renal crónica (ERC) | A long-term reduction in kidney function, which IgA nephropathy can lead to over time. |
Frequently asked questions about IgA nephropathy
Is IgA nephropathy an autoimmune disease?
Yes. Health authorities classify IgA nephropathy as an autoimmune kidney disease. The immune system produces an abnormal form of the antibody immunoglobulin A, then makes other antibodies against it. Together these form immune clumps that settle in the kidney’s filters and cause inflammation. This is different from an infection of the kidney, even though flare-ups of visible blood in the urine often follow an infection elsewhere, such as a sore throat.
What is the life expectancy with IgA nephropathy?
The outlook varies a great deal from person to person. Many people live a normal lifespan with stable kidney function, especially when protein in the urine is low and blood pressure is well controlled. A smaller group progresses toward kidney failure over many years and may eventually need dialysis or a transplant. The amount of protein in the urine and the trend in eGFR over time are among the most useful guides, which is why long-term monitoring is so important.
Is IgA nephropathy the same as Henoch-Schonlein purpura?
They are closely related but not identical. Both involve deposits of the same abnormal IgA. IgA nephropathy mainly affects the kidneys, while IgA vasculitis (the newer name for Henoch-Schonlein purpura) also affects the skin with a rash, and often the joints and gut. Some doctors view them as different expressions of one underlying process. When IgA vasculitis involves the kidneys, the changes seen on biopsy can look very similar to IgA nephropathy.
Are there new treatments for IgA nephropathy?
Yes, and this is an unusually active area of research. Alongside long-standing blood-pressure and protein-lowering medicines, newer options include a gut-targeted form of budesonide, SGLT2 inhibitors, endothelin receptor antagonists, and complement inhibitors, with additional antibody-lowering drugs being studied in ongoing trials. Not every treatment is right for every person, so a nephrologist decides based on how much protein you lose and how your kidney function is trending.
Is there a special diet for IgA nephropathy?
There is no single diet that cures the disease, but food choices can support kidney health. A lower-salt diet helps control blood pressure and reduce fluid retention, and some people are advised to moderate protein intake depending on their kidney function. If swelling or advanced kidney disease is present, a dietitian may suggest adjusting potassium or phosphorus. Any diet changes should be personalized, so it is best to review them with your care team rather than following general rules.
How common is IgA nephropathy?
IgA nephropathy is considered one of the most common forms of primary glomerulonephritis, the group of diseases that damage the kidney’s filters directly. It is diagnosed worldwide but appears more often in some populations, including people of East Asian and European ancestry. Because many people have no symptoms, the true number affected is likely higher than the number formally diagnosed, and some cases are only found during testing for another reason.
Fuentes
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) — IgA Nephropathy — niddk.nih.gov
- Mayo Clinic — IgA nephropathy (Berger disease): Symptoms and causes — mayoclinic.org
- National Kidney Foundation — IgA Nephropathy (IgAN) — kidney.org
- Stoneman S, et al. — IgA Nephropathy in Adults: A Review — JAMA, 2026 — doi.org/10.1001/jama.2025.25020
- Lafayette R, et al. — Efficacy and safety of a targeted-release formulation of budesonide in primary IgA nephropathy (NefIgArd), 2-year results — The Lancet, 2023 — doi.org/10.1016/S0140-6736(23)01554-4
- Heerspink HJL, et al. — Atrasentan in Patients with IgA Nephropathy — New England Journal of Medicine, 2024 — doi.org/10.1056/NEJMoa2409415
- Perkovic V, et al. — Alternative Complement Pathway Inhibition with Iptacopan in IgA Nephropathy — New England Journal of Medicine, 2024 — doi.org/10.1056/NEJMoa2410316
- Perkovic V, et al. — Sibeprenlimab in IgA Nephropathy, interim analysis of a phase 3 trial — New England Journal of Medicine, 2025 — doi.org/10.1056/NEJMoa2512133
- Floege J, et al. — Treatment of patients with IgA nephropathy: a call for a new paradigm — Kidney International, 2025 — doi.org/10.1016/j.kint.2025.01.014
- ClinicalTrials.gov — Felzartamab in Adults With IgA Nephropathy (PREVAIL), NCT06935357, 2025 — clinicaltrials.gov/study/NCT06935357
- ClinicalTrials.gov — Sibeprenlimab in Immunoglobulin A Nephropathy (VISIONARY), NCT05248646 — clinicaltrials.gov/study/NCT05248646
Lecturas recomendadas
- Resultados del examen general de orina (EGO): guía para entenderlos
- Panel de función renal: cómo leer tus estudios de sangre renales
- Hematuria (sangre en la orina): causas y síntomas
- Proteína en la orina: causas, síntomas y riesgos
- Immunoglobulin A (IgA): Understanding Your Blood Test
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