IgA nephropathy: symptoms, causes, treatment and outlook

The kidneys filter the blood through very fine filters called glomeruli. Kidney Research UK explains that in IgA nephropathy the immune system produces abnormally formed immunoglobulin A, which becomes trapped in these filters and damages and scars the kidney over time. IgA normally helps fight infections, and why the abnormal form is made is not yet known.

Kidney Care UK describes it as one of the most common causes of damage to the filters of the kidneys that can cause kidney failure, while stressing that it is a rare condition overall. It was previously known as Berger's disease and is usually diagnosed in young adults, though it often goes unrecognised for long periods because there are no symptoms.

It is related to IgA vasculitis, formerly Henoch-Schonlein purpura, which can affect the skin, gut, joints and kidneys, whereas IgAN itself affects only the kidneys, according to Kidney Care UK.

The NHS says that early chronic kidney disease usually causes no symptoms and is often found only when blood or urine tests are done for another reason. IgAN follows that pattern, and the clues are typically on testing rather than in how a person feels.

Visible blood in the urine is the symptom that most often brings people to medical attention. Kidney Care UK says urine may look red or dark brown, like a cola drink, and is more likely after an infection such as a cold or sore throat, usually fading after a few days. Kidney Research UK adds that visible blood can also follow a stomach upset or exercise.

• Blood in the urine, either visible or detectable only on testing.

• Protein in the urine, which may make it look frothy if there is a lot.

• Swelling or puffiness around the eyes, legs and feet.

• High blood pressure, which can itself damage the kidney if untreated.

• A raised creatinine on a blood test as kidney function falls.

• At more advanced kidney disease: tiredness, swollen ankles, feet or hands, shortness of breath and feeling sick, per the NHS.

Treatment focuses on protecting kidney function. Kidney Care UK says lifestyle measures are important for everyone with IgAN: losing weight if needed, regular exercise, stopping smoking or vaping and reducing salt. Kidney Research UK adds that controlling blood pressure is the main way of reducing protein in the urine.

Blood pressure medicines called ACE inhibitors or angiotensin receptor blockers (ARBs) are used, and Kidney Care UK says they may be prescribed if there is protein in the urine even when blood pressure is normal. It also says SGLT2 inhibitors are often prescribed to slow progression, and that targeted-release budesonide, a corticosteroid acting in the gut, can help slow the decline in kidney function by reducing the IgA that builds up in the kidneys.

Kidney Care UK describes sparsentan as having a greater protective effect than ACE inhibitors or ARBs, in which case those medicines are stopped. Kidney Research UK also lists immunosuppressive medicines, which dampen the immune system, and notes that hospitals may invite people to join clinical trials. Kidney Research UK reports that NICE issued final draft guidance in November 2023 recommending targeted-release budesonide as an add-on to ACE inhibitors or ARBs. It also lists news that a NICE decision on sparsentan was reversed in May 2025 and that the Scottish Medicines Consortium accepted sparsentan in June 2026. Which treatment is suitable for you depends on your kidney tests and national decisions, so your kidney team is the place for current details.

Diagnosis often starts with a routine urine test showing blood or protein, followed by blood tests and blood pressure measurement. Kidney Care UK says a kidney biopsy can confirm the diagnosis by showing IgA deposits in the glomeruli. Kidney Research UK states that at present doctors can only diagnose IgAN with a kidney biopsy, in which small samples of kidney tissue are examined under a microscope, with blood and urine tests used to gauge how well the kidneys are working.

The NHS says chronic kidney disease in general is diagnosed with blood and urine tests, and that the results can be used to give the disease a stage, with higher numbers showing more serious damage. People with a known risk such as high blood pressure or diabetes may be advised to have regular tests so kidney disease is found early.

A kidney specialist (nephrologist) usually oversees this work, since blood and urine tests alone cannot confirm the cause of the findings.

Kidney Care UK says IgAN is caused by increased production of the immunoglobulin A (IgA) protein, which the immune system normally produces to fight infections. In IgAN the protein gets stuck in the glomeruli, the kidney's microscopic filters. Over time it builds up and damages them, stopping the kidneys working properly.

Kidney Research UK says the body's immune cells produce abnormally formed IgA and that it is not yet known why this happens. Kidney Care UK adds that the exact factors involved have not been identified, that it is likely a range of genetic and environmental factors contribute, and that IgAN can very occasionally run in families although no genetic basis has yet been found.

Kidney Research UK describes IgAN as a variable condition. It could go away completely, though that is not very common, it could stay the same for years, kidney function may slowly decline, or kidneys may fail completely, leading to dialysis or a transplant. It adds that IgAN may recur after a kidney transplant.

The proportion who progress is quoted slightly differently by the two charities. Kidney Research UK says around 30 per cent of people go on to lose kidney function and need a transplant or dialysis, and that there are currently no reliable tests to predict who these progressors will be. Kidney Care UK says around 1 in 3 will need dialysis and/or a transplant within around 20 years of diagnosis. Both therefore point to a majority who do not reach kidney failure, but also to real uncertainty for each person.

Because the NHS notes that anyone with kidney disease, even if mild, has a higher risk of cardiovascular disease, looking after blood pressure, cholesterol and smoking matters alongside kidney-specific treatment.

Most people with IgAN are looked after by a kidney unit, with regular blood pressure checks, urine tests for blood and protein, and blood tests for kidney function. Kidney Research UK points to specialist nurses at kidney units as a point of contact, and to an annual UK IgAN patient information day, while Kidney Care UK notes the information days are supported by its hospital grants programme.

Visible blood in the urine, new swelling, breathlessness, or feeling very unwell should prompt medical advice. The NHS says to see a GP for persistent or worrying symptoms that could be caused by kidney disease. For sudden severe illness, NHS 111 or 999 is appropriate.

Pregnancy planning, new medicines and painkillers deserve a conversation with the kidney team. The NHS lists long-term regular use of non-steroidal anti-inflammatory drugs among causes of kidney disease generally, so checking before using them regularly is sensible.

On the NHS, IgAN is usually suspected after a GP urine or blood test and confirmed by a kidney biopsy under a nephrology team. Care continues in a kidney unit with regular monitoring. Kidney Research UK points to specialist nurses at kidney units as a contact, and to an annual UK IgAN Patient Information Day.

Some people see a kidney specialist privately for a second opinion or faster review. Tests and treatments follow the same principles, and results and medicines should be shared with your GP and kidney team so they stay in your record.