Berger’s disease, also known as IgA nephropathy, is the most common form of kidney inflammation worldwide. It happens when an antibody called IgA builds up in the kidneys, triggering damage that can range from harmless to severe. Some people live with it for decades without major problems, while up to 30% progress to kidney failure within 10 years of diagnosis.
How Berger’s Disease Damages the Kidneys
Your immune system normally produces IgA antibodies to fight off infections in the gut and respiratory tract. In Berger’s disease, the body produces a defective version of one type (IgA1) that lacks certain sugar molecules on its surface. This abnormal IgA1 gets flagged by other antibodies, forming clumps called immune complexes that circulate in the bloodstream.
These immune complexes eventually lodge in the kidney’s filtering units, specifically in a region called the mesangium, which acts as structural support for the tiny blood vessels that filter your blood. Once stuck there, the complexes latch onto cell surface receptors and trigger a chain reaction. The mesangial cells begin multiplying abnormally, the surrounding tissue expands, and immune cells flood the area. The resulting inflammation produces scarring compounds that, over time, replace healthy kidney tissue with fibrous scar tissue. This gradual scarring is what ultimately reduces kidney function.
What makes the process self-reinforcing is that the initial deposits stimulate the mesangial cells to produce even more receptors, which attracts more IgA deposits. It’s a feedback loop that can quietly run for years before symptoms appear.
Who Gets Berger’s Disease
Berger’s disease is most commonly diagnosed in people during their teens through their 30s, though it can appear at any age. Men develop it more often than women. The condition shows a striking geographic and ethnic pattern: it’s most common in people of Asian descent, less common in those of European descent, and least common in people of African descent. These differences likely reflect a combination of genetic susceptibility and screening practices, since countries like Japan routinely screen urine in schoolchildren, catching cases that might go undetected elsewhere.
Symptoms and Early Warning Signs
The hallmark symptom is visible blood in the urine, which can appear brown, red, or cola-colored. This often shows up during or just after an upper respiratory infection, a sore throat, or a gut illness. The timing is distinctive: unlike most kidney diseases that develop independently of infections, Berger’s disease flares alongside them. Doctors sometimes call this “synpharyngitic hematuria” because the bloody urine coincides with throat infections rather than following them weeks later (which would suggest a different condition).
Many people, however, have no visible symptoms at all. Their disease is discovered only when a routine urine test reveals microscopic amounts of blood or small amounts of protein. Other symptoms that can develop as the disease progresses include foamy urine from protein leaking through damaged filters, swelling in the hands and feet, pain below the ribs on one or both sides, high blood pressure, and persistent fatigue.
How Berger’s Disease Is Diagnosed
A kidney biopsy is the only way to definitively diagnose Berger’s disease. Urine and blood tests can raise suspicion, but confirming the diagnosis requires removing a tiny sample of kidney tissue and examining it under specialized microscopy. Pathologists look for IgA deposits that are either the dominant or co-dominant type of antibody present in the mesangium. About half of biopsies also show deposits of other antibody types (IgG or IgM), and more than 90% show a complement protein called C3, which is part of the immune system’s attack machinery.
The biopsy also reveals how much damage has already occurred. An international scoring system called the Oxford classification grades the tissue based on how much cell overgrowth, scarring, and inflammation is present. This grading helps predict how the disease will behave and guides treatment decisions.
Treatment Options
Treatment starts with blood pressure control, which is the single most important factor in slowing kidney damage. The target is aggressive: below 120/70 mmHg. Blood pressure medications that block a hormone called angiotensin are the foundation of care because they reduce the amount of protein leaking through the kidneys, which itself causes further damage. Maximizing the dose of these medications is standard practice for everyone with the diagnosis.
For people with significant protein in their urine (above about 1 gram per day) despite blood pressure treatment, the options have expanded considerably. The 2025 international kidney guidelines now recommend a targeted-release form of budesonide as the preferred first-line treatment for high-risk cases. This medication is designed to act on the gut’s immune tissue, where much of the defective IgA is produced, rather than flooding the whole body with steroids. Clinical data shows it reduces protein leakage and slows the decline in kidney function with fewer side effects than traditional steroid pills.
A newer drug called sparsentan, which blocks two pathways involved in kidney scarring simultaneously, is now also included in the guidelines as an add-on option. When the targeted budesonide isn’t available, doctors may use a lower-dose systemic steroid regimen, though the benefits in European populations have been questioned after a German trial showed that high-dose steroids improved short-term numbers without improving long-term outcomes like avoiding dialysis.
A class of diabetes medications (SGLT2 inhibitors) has also earned a place in the treatment toolkit, not for blood sugar control, but because these drugs independently protect kidney function by reducing pressure inside the filtering units.
Diet and Lifestyle Changes
Reducing sodium intake is one of the most practical things you can do. Lowering salt helps control blood pressure and reduces the swelling that comes with protein loss. The National Institute of Diabetes and Digestive and Kidney Diseases recommends limiting sodium and quitting smoking as core lifestyle measures. Your doctor may also adjust your dietary protein or other nutrients depending on how much kidney function you’ve lost, but there’s no single “Berger’s disease diet” that applies to everyone. Recommendations are tailored based on your lab results and symptoms.
Long-Term Outlook
Berger’s disease is unpredictable. Some people have a single episode of bloody urine and never develop significant kidney problems. Others experience a slow, steady decline over decades. In a long-term study tracking patients for up to 30 years, 87% still had functioning kidneys at 10 years, 73% at 20 years, and 65% at 30 years. The wide range in outcomes reflects the fact that several factors influence progression: heavy protein in the urine, high blood pressure, and extensive scarring on biopsy all point toward a more aggressive course.
People with only microscopic blood in the urine and minimal protein loss generally have a favorable prognosis. The challenge is that the disease can be silent for years while damage accumulates, which is why regular monitoring of kidney function and urine protein levels matters even when you feel completely fine.