IgA nephropathy, also called IgA nephritis or Berger disease, is a chronic inflammation of the tiny filters in the kidneys. It most often affects young adults and typically causes blood in the urine a couple of days after a cold. The course varies a lot: many stay stable for decades, but some develop kidney failure. Treatment can slow it down.
By the Nyrami editorial teamPublished 9 October 20268 min read
Perhaps you noticed reddish brown urine after a sore throat, or were told there was blood and protein in a urine sample. Perhaps you have just had a kidney biopsy and got the answer IgA nephropathy. Here you will learn what the disease is, how it differs from other kinds of kidney inflammation, how it is treated, and what the numbers say about the future.
IgA nephropathy is a chronic inflammation of the kidney filters, the glomeruli. It happens when an altered form of the antibody immunoglobulin A (IgA) forms clumps with other antibodies and gets stuck in the kidneys. There it causes inflammation and gradual damage. It is not an infection, and it is not contagious. IgA nephritis, IgA glomerulonephritis and Berger disease are other names for the same condition.
It is the most common form of primary glomerulonephritis in the world, and a frequent cause of severe kidney failure in young adults. It usually starts in young adulthood, affects men more often than women, and can also affect children. In Europe, 20 to 30 per million people develop it each year, according to Store medisinske leksikon (the Norwegian medical encyclopaedia). It is far more common in East Asia.
Glomerulonephritis is an umbrella term for inflammation of the kidney filters caused by a fault in the immune system, not directly by bacteria or viruses. Typical findings are blood and protein in the urine, often with high blood pressure. IgA nephropathy is one of many such diseases, and the most common chronic form.
Diseases of the kidney filters were behind eighteen per cent of those registered with stage 5 kidney failure in the Norwegian Renal Registry in 2024, before dialysis or transplantation. More about kidney disease in general is in Chronic kidney disease.
Many people with IgA nephropathy notice nothing for a long time, and the disease is found by chance when a urine test shows blood or protein. The most typical sign is visible blood in the urine, red, brown or cola coloured, that appears during or just after a cold or sore throat and then clears again.
How protein in urine is measured, and what the numbers mean, is explained in Protein in urine.
In IgA nephropathy, throat and airway infections switch on the immune system, and this can flare up the inflammation in the kidneys. The blood in the urine then appears quickly, often one to two days after the infection started. In post-infectious glomerulonephritis it takes longer, usually one to two weeks. The timing helps the doctor tell them apart, but only tests can settle it.
IgA nephropathy and post-infectious glomerulonephritis
When does blood appear in the urine?
Who gets it?
Course
Diagnosis
IgA nephropathy is not inherited in a simple way, as polycystic kidney disease is, for example. Inherited traits make some people more susceptible, but something must also trigger the disease. Most people who get it have no one in the family with the same diagnosis. If you have a close relative with IgA nephropathy, your risk is still somewhat higher.
There is no genetic test for IgA nephropathy. If someone in your family has it, a urine test and a blood pressure check with your GP (fastlege) is a simple way to check yourself. More about inherited kidney diseases is in Is kidney disease hereditary?.
IgA nephropathy can only be confirmed with a kidney biopsy, a small tissue sample taken from the kidney with a thin needle. Under the microscope, the pathologist sees IgA deposits in the kidney filters. No blood or urine test can make the diagnosis on its own.
Investigation often starts with your GP. If blood in the urine persists, or protein in the urine is newly found, you should be referred to a kidney specialist (nephrologist), who decides whether you need a biopsy. The international KDIGO guideline (2025) recommends considering a biopsy in all adults with suspected IgA nephropathy and urine protein of 0.5 grams a day or more. The biopsy result gets a so called MEST-C score, which together with eGFR, blood pressure and urine protein says something about the risk ahead.
Treatment has two aims: to calm the inflammation that damages the kidneys, and to protect the kidney function that is left. The foundation is a blood pressure medicine of the ACE inhibitor or angiotensin II receptor blocker (ARB) type, which also reduces protein leakage, often together with an SGLT2 inhibitor. Which medicines suit you is decided by your kidney specialist together with you.
Several new medicines have arrived in recent years. Targeted release budesonide (Kinpeygo), released in the gut, reduces production of the altered IgA, and sparsentan (Filspari) works both as a blood pressure medicine and by blocking the hormone endothelin. Both are approved in Europe. In Norway, Nye metoder (the Norwegian system for new treatments) decided in 2025 that Kinpeygo will not be introduced in public hospitals, because the price was too high for the documented benefit. Sparsentan was not taken into use in 2025, but is now being assessed again, and the price has not yet been settled. Several other medicines are being tested in trials. Ask your kidney specialist what is relevant for you, and whether you can take part in a study.
If you are planning a pregnancy, talk to your kidney specialist well in advance. Some of the medicines must not be used in pregnancy, and a Norwegian study found pre-eclampsia in many women with IgA nephropathy, even when the disease was thought to be mild.
The course of IgA nephropathy varies a great deal. Some recover, many stay stable for decades, and some gradually lose kidney function. Norwegian figures show that around thirty per cent reach severe kidney failure needing dialysis or a transplant within 20 years. That also means most people do not within that time.
What matters most for the outlook is how much protein leaks into the urine over time, blood pressure, eGFR at diagnosis, and what the biopsy shows. Newer research shows that even fairly small amounts of protein in the urine over many years carry risk, which is why treatment goals have become stricter. Your doctor can use an international calculator (International IgAN Prediction Tool) to estimate your risk.
The figures describe groups, not you. They are based on patients followed before the newest medicines arrived. Read more in Can kidney failure get better?.
Contact your GP if you see blood in your urine, even if it clears by itself, or if your urine stays foamy, your legs swell or your blood pressure is high. If you already have IgA nephropathy, tell your doctor about new episodes of visible blood in the urine.
With IgA nephropathy, it is the numbers over time that count. In the Nyrami app you can keep your values, such as eGFR, albumin and blood pressure, in one place and see them explained in words. The food scanner assesses sodium and more for you, and the recipes are assessed per portion. The app is free for iPhone and Android.
Turns the advice into something you can use in the shop and the kitchen: scan food and see potassium, phosphorus and salt assessed for you, and follow your numbers over time. Free on iPhone and Android.
Acute kidney failure, which doctors now call acute kidney injury (AKI), means the kidneys stop working properly over hours or days. Common causes are fluid loss, serious infection and certain medicines. Many people recover fully or almost fully when the cause is treated quickly, but the risk of chronic kidney disease rises afterwards.
A simple cyst on the kidney is common and almost always harmless. Polycystic kidney disease (ADPKD) is something else: an inherited disease in which many cysts grow in both kidneys. Each child has a one in two chance of inheriting it. Good blood pressure control and sometimes the medicine tolvaptan can slow it down.
Nephrotic syndrome means the kidneys leak a large amount of protein into the urine, so albumin in the blood falls and the body holds on to water. Typical signs are swelling around the eyes and in the legs, and foamy urine. Most children respond well to steroids. In adults, treatment depends on the cause.
