What is IgA nephropathy?

IgA nephropathy (IgAN, pronounced “I-Gan”) is a rare kidney condition that occurs when a protein called Immunoglobulin A (IgA) gets ‘trapped’ in the filters of the kidneys and causes inflammation and damage. This affects the kidneys’ ability to clear waste from the body.

IgAN affects around 1 in 50,000 people in the UK. It is one of the most common causes of damage to the filters of the kidneys and can cause kidney failure. Men are more likely to be affected than women.

IgAN was previously called Berger’s disease.

What are the signs and symptoms of IgAN?

Most people with IgAN do not have any symptoms. For those who do, the common symptoms are:

• Blood in the urine (haematuria) – the urine may look red or dark brown (like a cola drink). This is more likely to occur after an infection such as a cold or sore throat and usually fades after a few days. The haematuria may also be invisible to the naked eye but seen under a microscope when the urine is tested (microscopic haematuria).
• Protein in the urine (proteinuria/albuminuria) – this is likely to only be found when the urine is tested with a dipstick or sent to the laboratory for analysis, but if there is a lot of protein, the urine may look frothy
• Swelling or puffiness (oedema) in different parts of the body, especially around the eyes, legs and feet
• High blood pressure – this can damage the structure of the kidney if it is not treated.

What causes IgAN?

IgAN is caused by increased production of the Immunoglobulin A protein, which is produced by the immune system to fight infections in the body. In people with IgAN, this protein gets stuck in the microscopic blood vessels of the kidney (glomeruli). Over time the protein builds up and damages the glomeruli. This stops the kidneys from working properly.

How is IgAN diagnosed?

IgAN is often suspected after a routine urine test shows signs of blood and/or protein. A kidney biopsy can confirm the diagnosis by showing IgA deposits in the glomeruli when they are examined under a microscope.

IgAN is usually diagnosed in young adults, although it often goes unrecognised for long periods of time before diagnosis because of a lack of symptoms.

Does IgAN affect other parts of the body?

IgAN only affects the kidneys, but it is related to another condition called IgA vasculitis, (previously known as Henoch Schonlein Purpura or HSP) that can affect the skin, gut and joints, as well as the kidneys.

Does IgAN run in families?

IgAN can very occasionally run in families, although no genetic basis has yet been found. It is likely that a range of genetic and environmental factors contribute to the development of the condition. However, the exact factors involved have not yet been identified.

How is IgAN treated?

Treatment aims to protect kidney function. Lifestyle measures such as losing weight, regular exercise, stopping smoking/vaping and reducing salt in the diet are important for all people with IgAN.

Blood pressure medication may also be prescribed, such as angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs). If you have protein in the urine, you may be prescribed these medicines, even if you do not have high blood pressure.

SGLT2 (sodium-glucose co-transporter 2) inhibitors are also often prescribed to slow the progression of IgAN.

Targeted-release budesonide can help to slow the decline of kidney function by reducing the amount of the IgA protein that builds up in the kidneys.

A medication called sparsentan has a greater protective effect on the kidneys than ACE inhibitors or ARB blockers and if used, ACE inhibitors or ARB blockers need to be stopped.

In most people, kidney function deteriorates slowly. Around 1 in 3 people with IgAN will require dialysis and/or transplant within around 20 years of diagnosis.

Where can I get more information or support about IgAN?

For more information on IgAN, including its diagnosis, symptoms and treatment, visit the Leicester IgAN Research Group.

There are currently a number of clinical trials taking place to research further treatment options for IgAN. Talk to your kidney team for more information.

Publication date: 09/2026

Review date: 09/2029

IgAN patient information days: supported by Kidney Care UK

Kidney Care UK’s Hospital Grants programme funds improvements to patient care and services across the UK. One of the initiatives funded are IgAN patient information days at Leicester University.

This is the opening talk from the 10th IgA Nephropathy Patient Information Day, held in Cardiff on 15 February 2025. In this session, Professor Jonathan Barratt (University of Leicester) provides a comprehensive update on the latest developments in IgA nephropathy research and treatment, including clinical trials, emerging therapies, and future directions in the field.