IgA nephropathy is the most common form of glomerulonephritis (kidney inflammation caused by immune system problems) in the world. Globally, at least 25 new cases per million people are diagnosed each year, making it more frequent than all other types of kidney-filtering diseases. But how common it actually is depends heavily on where you live, your ethnic background, and whether your country screens for early signs of kidney trouble.
Global Incidence and Prevalence
At a rate of roughly 2.5 new diagnoses per 100,000 people each year, IgA nephropathy outnumbers every other glomerular disease. For comparison, the next most common type (membranous nephropathy) occurs at about half that rate, and focal segmental glomerulosclerosis is diagnosed at roughly a quarter of IgA nephropathy’s rate.
In Europe, the estimated point prevalence is about 2.53 per 10,000 people, though this varies widely by country, from 1.14 per 10,000 in Spain to 5.98 per 10,000 in Lithuania. These numbers almost certainly undercount the true burden. IgA nephropathy can only be confirmed through kidney biopsy, an invasive procedure that many doctors avoid in patients with mild symptoms. Most European countries also lack routine urine screening programs that would catch early, silent cases. Even when urine abnormalities are detected, general practitioners sometimes overlook them or refer patients to urologists rather than kidney specialists. The disease can exist for years without obvious symptoms, so a significant number of people likely have it without knowing.
Why Geography Matters So Much
The difference in rates across regions is striking. Japan sees 39 to 45 new cases per million people each year. France diagnoses 25 to 31 per million. The United Kingdom logs only about 10 per million. In African countries, IgA nephropathy accounts for fewer than 10% of all biopsy-confirmed kidney diseases, while in Japan, China, France, and Germany it makes up over 40%.
Some of this gap reflects genetics. Studies comparing genetic risk scores across ethnic groups consistently find that East Asians and Native Americans carry the highest inherited risk, Middle Easterners and Europeans fall in the middle, and people of African descent have the lowest risk. This pattern holds even within the United States: Asian Americans show the highest genetic risk scores, white Americans are intermediate, and African Americans the lowest.
Screening practices also play a role. Japan conducts routine school urinalysis, which catches kidney problems early. That program alone pushes Japan’s detection rate for children to 99 cases per million per year, far higher than the 2 per million per year seen in European children, where no such screening exists. Higher biopsy rates in certain countries amplify the apparent gap further, since you can only count what you look for.
Who Gets Diagnosed
IgA nephropathy is typically diagnosed in young adults, most often between the late teens and the 30s, though it can appear at any age. Men are diagnosed more frequently than women in most studies. The disease is not rare in children, but pediatric cases are often milder and less likely to be biopsied outside of countries with screening programs, meaning many childhood cases go unrecognized.
The Real Number Is Likely Higher
Every published statistic on IgA nephropathy is based on biopsy-confirmed diagnoses, which means the true prevalence is almost certainly larger than what the data show. Several forces push the real number upward. Many people with mild protein or blood in their urine never get referred to a nephrologist. Doctors may choose not to biopsy patients with stable, mild disease, particularly when treatment options were historically limited. And in countries without population-level urine screening, the disease can progress silently for years before anyone notices.
The COVID-19 pandemic added another wrinkle. Kidney biopsy rates dropped in many countries during 2020 and 2021, temporarily reducing the number of new diagnoses and creating a further gap between confirmed cases and actual prevalence.
Long-Term Outlook and Progression
IgA nephropathy is not always a progressive disease, but it can be. Roughly 15 to 40 percent of people diagnosed will experience worsening kidney function that eventually leads to kidney failure within 10 to 20 years. The wide range reflects how much individual outcomes depend on factors like the amount of protein in your urine, blood pressure control, and how early the disease is caught.
Updated guidelines from 2025 now set a more aggressive treatment target, aiming to bring protein in the urine below 0.5 grams per day (down from the previous target of under 1 gram). The shift reflects growing evidence that lower protein levels in the urine correspond with better long-term kidney survival. New treatment options, including a targeted form of an anti-inflammatory steroid and a dual-action blood pressure medication, have expanded the toolkit beyond the older approach of simply controlling blood pressure and waiting.
For the many people with stable, low-level disease, the prognosis is good. The challenge is that IgA nephropathy often doesn’t announce itself with dramatic symptoms, so knowing how common it is, and who’s at higher risk, matters for catching it before kidney damage accumulates.