What Is IgA Nephropathy?

IgA nephropathy — also called Berger's disease — is a kidney condition in which a normally helpful antibody, immunoglobulin A (IgA), collects in the kidney's tiny filters and inflames them. It is the most common primary glomerular disease in the world, yet many people have never heard of it until a urine test comes back abnormal. This article explains what the condition is, how it is found, how it is treated, and what living with it looks like — in plain language. A fuller guide, with videos and the risk calculators, is on our IgA nephropathy hub page.

What happens in the kidneys

Your kidneys clean your blood through millions of microscopic filters called glomeruli. In IgA nephropathy, the body produces a slightly abnormal form of IgA. Instead of passing harmlessly through, it lodges in the glomeruli and triggers inflammation. Over months and years, repeated inflammation can scar the filters. Scarred filters leak substances they should keep in the blood — red blood cells and protein escape into the urine — and in some people the kidneys gradually lose their cleaning ability.

IgA nephropathy is an immune-system condition. It is not an infection, it cannot be caught, and it is not caused by anything a person did. Why a particular person develops it is not fully understood; genes and environment both seem to contribute.

Who gets IgA nephropathy?

The condition often appears in teenagers and young adults, and it is seen more frequently in people of Asian and European ancestry. Having a close relative with the condition raises the risk somewhat, although it is not inherited in a simple, predictable pattern. Episodes of visible blood in the urine often follow a cold, a sore throat or a stomach bug — infections stimulate IgA production, and the kidney inflammation flares with it. Our site's founder discusses the risk factors in depth in his ReachMD Clinician's Roundtable episode, linked from the hub page above.

Should family members be checked?

Because close relatives of someone with IgA nephropathy have a somewhat higher chance of kidney abnormalities that cause no symptoms, a simple urine test for parents, siblings and children is often suggested. It is quick and painless, and finding blood or protein early — whatever the cause — allows monitoring to start before any damage is done. Mention it to your specialist, who can advise whether it makes sense for your family.

Symptoms

Many people feel completely well, especially early on, and the condition is often discovered only because a routine urine test shows blood or protein. When symptoms do occur, they can include:

• Urine that looks red, pink or cola-coloured, often during or shortly after an infection
• Foamy urine, caused by protein leaking into it
• Swelling of the hands, feet or around the eyes
• High blood pressure
• Tiredness, usually only when kidney function has fallen substantially

An episode of visible blood in the urine usually settles within a few days, but it should always be reported — blood in the urine has several possible causes, and a new episode should not simply be assumed to be the IgA nephropathy.

How it is diagnosed

Diagnosis starts with urine and blood tests: a dipstick and microscope examination of the urine, a urine albumin- or protein-to-creatinine ratio to measure protein leakage, blood tests for kidney function (creatinine and the estimate derived from it, eGFR), and a blood-pressure check. Other causes of blood or protein in the urine — infection, kidney stones and other glomerular diseases among them — need to be considered and ruled out.

The definitive test is a kidney biopsy: a small sample of kidney tissue, taken through the back with a needle under local anaesthetic and ultrasound guidance, examined under the microscope. The biopsy shows the IgA deposits directly and reveals how much of the tissue is inflamed or scarred — information used to judge the likely course and to plan treatment. Pathologists summarise the biopsy using the Oxford (MEST-C) classification. Our guide What Is a Kidney Biopsy? explains the procedure itself, and the kidney biopsy preparation guide covers how to get ready for the day.

The numbers that matter — and predicting the course

Because IgA nephropathy changes slowly, it is followed with a small set of numbers: the amount of protein in the urine (measured with a ratio such as the urine ACR), the eGFR trend, and blood pressure. Of these, urine protein is the strongest everyday guide to how active the disease is and how well treatment is working.

In practice this means regular review appointments — often every few months at first, then less frequently once things are stable — with blood and urine tests each time, plus home blood-pressure readings in between if your team recommends them. Doctors can also estimate the future course more formally. The International IgA Nephropathy Prediction Tool combines age, kidney function, urine protein, blood pressure, medicines and the biopsy scores to estimate the risk of kidney function declining substantially over the following years, and the Kidney Failure Risk Equation gives a two- and five-year estimate during follow-up. These are probabilities, not certainties — and because protein levels and blood pressure respond to treatment, the estimates are revisited over time. The hub page explains both tools in more detail.

Treatment: protecting the kidneys

There is currently no cure that removes IgA from the kidneys, so treatment aims to protect the filters and slow scarring. For most people the foundation is careful supportive care:

• Blood-pressure control, usually including a kidney-protective blood-pressure medicine (an ACE inhibitor or an ARB), which also reduces the protein leaking into the urine
• Cutting down on salt, keeping cholesterol in range, and not smoking
• SGLT2 inhibitors — medicines first developed for diabetes — now form part of kidney-protective care for many people with proteinuric kidney disease; your specialist will say whether one is suitable for you

For people whose urine protein stays high and whose risk of progression is judged greater, a kidney specialist may consider a course of steroids or other immune-suppressing treatment. These medicines have real side effects, so the decision is individual and is made with the specialist, weighing the biopsy findings and the monitoring numbers. Newer targeted treatments developed specifically for IgA nephropathy have begun to appear, and this is a fast-moving area — one more reason to stay connected to a kidney team. Whatever the plan, treating infections promptly and asking before using anti-inflammatory painkillers (such as ibuprofen) regularly are sensible precautions.

Living with IgA nephropathy

The outlook varies widely. Many people keep good kidney function for decades — particularly when urine protein is low and blood pressure is controlled — while a minority progress towards kidney failure over years. That wide range is exactly why regular monitoring matters: change is usually silent, and adjusting treatment early works best.

Day to day, living well with the condition mostly means keeping the routine: take medicines as prescribed, watch the salt, stay active, and keep every follow-up appointment and test. If you are planning a pregnancy, mention it to the kidney team early, as medicines and monitoring may need adjusting. To hear the condition explained by a transplant nephrologist, watch IgA Nephropathy — Kidney Zone Podcast, Episode 57. If kidney failure does eventually develop, dialysis and transplantation are the established treatments, and our condition guides cover both.

When to seek help promptly

Contact your kidney team promptly — or seek urgent care — if you notice: passing much less urine than usual; rapidly increasing swelling or new breathlessness; blood in the urine together with pain, clots, or difficulty passing urine; or very high home blood-pressure readings, severe headache, or changes in your vision.

References & further reading

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) — IgA Nephropathy: https://www.niddk.nih.gov/health-information/kidney-disease/iga-nephropathy

National Kidney Foundation — IgA Nephropathy: https://www.kidney.org/kidney-topics/iga-nephropathy

MedlinePlus — IgA Nephropathy (Medical Encyclopedia): https://medlineplus.gov/ency/article/000466.htm

KDIGO — Glomerular Diseases Guideline, IgA Nephropathy: https://kdigo.org/guidelines/iga-nephropathy/

Mayo Clinic — IgA Nephropathy (Berger's Disease): https://www.mayoclinic.org/diseases-conditions/iga-nephropathy/symptoms-causes/syc-20352268

This article is for general education only and is not medical advice. IgA nephropathy affects each person differently, and treatment decisions are individual — made with your kidney specialist.