IgA Nephropathy

Your kidneys clean your blood through millions of tiny filters called glomeruli. In IgA nephropathy, a normally helpful antibody — immunoglobulin A, or IgA — is made in a slightly abnormal form. It travels through the blood, collects in the glomeruli, and sets off inflammation there.

Over months and years, repeated inflammation can scar the filters. Scarred filters leak things they should keep — red blood cells and protein pass into the urine — and, in some people, the kidneys gradually lose their ability to clean the blood. IgA nephropathy is the most common primary glomerular disease in the world. It often appears in teenagers and young adults, and it is seen more often in people of Asian and European ancestry.

It is an immune-system condition, not an infection, and it is not contagious. Why a particular person develops it is not fully understood; genes and environment both seem to play a part.

Many people with IgA nephropathy feel completely well, especially early on. The condition is often picked up only because a routine urine test shows blood or protein. When there are signs, they can include:

• Urine that looks red, pink or cola-coloured — often during, or a day or two after, a cold, sore throat or stomach bug
• Foamy urine, a sign of protein leaking into the urine
• Swelling of the hands, feet or around the eyes
• High blood pressure
• Tiredness or other symptoms of reduced kidney function, usually only in more advanced disease

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

The first steps are urine and blood tests: a urine dipstick and microscopy to confirm blood and protein, a urine albumin- or protein-to-creatinine ratio to measure how much protein is leaking, 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 — such as infection, kidney stones or other glomerular diseases — 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, is examined under the microscope. It shows the IgA deposits directly, and how much of the kidney tissue is inflamed or scarred — information doctors use to judge risk (one widely used scoring system is called the Oxford classification). Our kidney biopsy preparation guide explains what to expect, and the linked article below walks through the procedure itself.

Because IgA nephropathy changes slowly, it is followed with a small set of numbers, checked regularly even when you feel well:

• Urine protein (albumin-to-creatinine or protein-to-creatinine ratio) — the strongest everyday guide to how active the disease is and how well treatment is working
• eGFR — the estimate of overall kidney function, followed as a trend over time rather than as a single reading
• Blood pressure — both a target of treatment and a driver of further damage when it runs high

The calculator linked below works out the urine ACR from a urine sample result; our eGFR calculator does the same for kidney function.

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 lowers the amount of protein leaking into the urine
• Cutting down on salt, keeping cholesterol in range, and not smoking
• SGLT2 inhibitors — a class of medicines first developed for diabetes — are now 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 protein levels stay high and whose risk of progression is judged higher, a kidney specialist may also consider a course of steroids or other immune-suppressing treatment. These medicines carry real side effects, so the decision is individual and is made with the specialist, weighing the biopsy findings and the monitoring numbers above. 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 taking regular anti-inflammatory painkillers (such as ibuprofen) are sensible precautions.

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 range is exactly why the regular monitoring matters: change is usually silent, and early adjustments to treatment work best.

Day to day, living well with the condition mostly means keeping the routine: take the medicines as prescribed, watch the salt, stay active, keep every follow-up and blood and urine test, and tell your team about new symptoms — visible blood in the urine, increasing swelling, or a big drop in how much urine you pass. If you are planning a pregnancy, mention it to the kidney team early, as they may want to adjust medicines and monitoring. If kidney failure does eventually develop, dialysis and transplantation are the established treatments, and our guides to both are linked at the foot of this page.

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
• Very high home blood-pressure readings, severe headache, or changes in your vision