Biological Causes
Immunoglobulin A nephropathy is an autoimmune disorder caused by a defect in the immune system. The body produces a specific type of immunoglobulin A (IgA) antibody that is slightly malformed. When these antibodies circulate in the blood, the immune system recognizes them as foreign and attaches other antibodies to them, forming clumps called immune complexes. These complexes get stuck in the glomeruli, the tiny filtering units of the kidneys. This deposition triggers an inflammatory reaction that damages the kidney tissue over time, leading to the leakage of blood and protein into the urine.

Risk Factors and Triggers
Several factors increase the likelihood of developing this condition. Genetics play a role, as the disease runs in some families and is significantly more common in people of Asian and Caucasian descent compared to those of African descent. Men are more likely to be diagnosed than women. The condition often flares up after a trigger event, most notably upper respiratory infections like a cold, sore throat, or sinus infection, or sometimes gastrointestinal infections. These infections stimulate the immune system to produce more IgA, worsening the buildup in the kidneys.

Prevention
There is currently no known way to prevent the underlying development of immunoglobulin A nephropathy because its exact cause is linked to genetics and the immune system. Primary prevention strategies do not exist. However, once diagnosed, secondary prevention focuses on slowing the progression of kidney damage. This involves strictly managing blood pressure, reducing protein loss in urine through medication, and maintaining a healthy lifestyle. Avoiding smoking is critical, as smoking accelerates kidney damage.

Signs and Symptoms
The disease often remains silent for years, but when symptoms appear, they can vary in severity. The most distinct symptom is episodes of cola-colored or tea-colored urine, which indicates visible blood in the urine (gross hematuria), often occurring during or shortly after a respiratory infection. Other common signs include:

• Foamy or bubbly urine caused by excess protein leakage (proteinuria).
• Pain in the flank or back, usually on one or both sides below the ribs.
• Swelling (edema) in the hands, feet, ankles, or abdomen due to fluid retention.
• High blood pressure, which may be the first sign detected during a routine checkup.

Diagnostic Tests
Clinicians use a combination of laboratory tests to identify the condition. A urinalysis is the first step, detecting microscopic blood and protein that may not be visible to the naked eye. Blood tests measure creatinine levels to estimate how well the kidneys are filtering waste (eGFR). However, these tests only suggest kidney damage. The definitive diagnosis requires a kidney biopsy. During this procedure, a doctor extracts a tiny piece of kidney tissue and examines it under a microscope to confirm the presence of IgA deposits in the glomeruli.

Differential Diagnosis
Doctors must rule out other conditions that cause similar symptoms. These include other forms of glomerulonephritis, urinary tract infections, kidney stones, or Alport syndrome. The biopsy distinguishes immunoglobulin A nephropathy from these other disorders by revealing the specific immune deposits unique to this disease.

Medications
Treatment focuses on slowing disease progression and managing symptoms rather than curing the underlying immune defect. The first line of defense usually involves blood pressure medications known as ACE inhibitors or ARBs. These drugs lower blood pressure and significantly reduce protein leakage, protecting the kidneys from further damage. Modern treatment options have expanded to include SGLT2 inhibitors, which were originally diabetes drugs but are now proven to protect kidney function. In cases with high risk of progression, doctors may prescribe corticosteroids or targeted immune-modulating drugs like budesonide formulations designed specifically for the gut, or newer therapies like sparsentan that block specific pathways involved in kidney scarring.

Lifestyle and Self-Care
Adopting a kidney-friendly lifestyle is an essential part of management. Patients are often advised to lower their sodium intake to help control blood pressure and reduce swelling. In some stages of the disease, a dietitian may recommend limiting dietary protein to reduce the workload on the kidneys. Quitting smoking is strongly recommended, as tobacco use damages blood vessels and accelerates the decline of kidney function. Maintaining a healthy weight and staying active also supports overall cardiovascular and renal health.

When to Seek Medical Care
Regular monitoring is vital, but immediate medical attention is needed if specific red-flag symptoms occur. Patients should see a doctor if they notice sudden swelling in the legs or face, difficulty breathing, or a significant decrease in urine output. Persistent bubbly urine or recurring visible blood in the urine warrants a prompt appointment. If blood pressure readings are consistently high despite medication, urgent evaluation is necessary to prevent rapid kidney damage or stroke.

Severity and Disease Course
The severity of immunoglobulin A nephropathy varies widely among individuals. For some, the condition is mild and stable, causing only low-level blood in the urine with normal kidney function for decades. For others, it is a progressive disease that gradually scars the kidneys. The course is typically chronic, spanning many years. Doctors use risk prediction tools based on biopsy results, blood pressure, and protein levels to estimate the likelihood of progression. Factors that worsen the prognosis include persistently high protein in the urine, uncontrolled high blood pressure, and reduced kidney function at the time of diagnosis.

Long-term Complications
The most significant complication is the development of chronic kidney disease (CKD), which can advance to end-stage renal disease (ESRD). Approximately 20 to 40 percent of people with this condition will eventually require dialysis or a kidney transplant, usually within 20 years of diagnosis. Other complications include high blood pressure, which can lead to heart disease, and nephrotic syndrome, a cluster of symptoms involving very high protein levels in urine and low protein in the blood. Even after a kidney transplant, the disease can recur in the new kidney, although it rarely leads to the failure of the transplanted organ.

Effects on Life Expectancy
Life expectancy is generally normal for patients whose disease remains mild or responds well to treatment. However, if the disease progresses to kidney failure, life expectancy can be impacted by the complications of dialysis and kidney disease. Early diagnosis and aggressive management of blood pressure and proteinuria significantly improve the long-term outlook and delay or prevent the need for kidney replacement therapy.

Living with the Condition
Managing this condition requires incorporating health monitoring into daily routines. Patients may need to check their blood pressure at home regularly and attend frequent medical appointments for blood and urine tests. Fatigue can be a factor, especially if kidney function declines, requiring adjustments to work or school schedules. Emotional stress regarding the potential for future kidney failure is common, and seeking support from patient advocacy groups or counselors can be beneficial. Dietary changes, such as preparing low-salt meals, become a standard part of daily life.

Questions to Ask Your Healthcare Provider
To better understand the condition and treatment plan, patients should ask their provider the following questions:

• What is my current level of kidney function (eGFR) and what does it mean?
• How much protein is in my urine, and is it increasing or decreasing?
• What are the specific side effects of the medications you are prescribing?
• Do I need to make specific changes to my diet, such as limiting protein or potassium?
• How often should I have my blood pressure and labs checked?
• Am I a candidate for any new treatments or clinical trials?

Q: Is immunoglobulin A nephropathy hereditary?
A: While it is not directly inherited in a simple pattern like some genetic diseases, there is a genetic component. Having a family member with the condition or related autoimmune disorders increases the risk, but most cases occur sporadically without a strong family history.

Q: Will I definitely need dialysis?
A: No, not everyone with this condition needs dialysis. A significant number of patients have a mild form of the disease that does not lead to kidney failure. With modern treatments, the progression can often be slowed significantly.

Q: Can I still exercise with this condition?
A: Yes, moderate exercise is generally encouraged as it helps control blood pressure and maintain a healthy weight. However, extremely strenuous exercise can sometimes cause temporary bloody urine in people with this condition, so it is best to consult a doctor about the right intensity.

Q: Is there a special diet I must follow?
A: Most patients benefit from a low-sodium diet to help manage blood pressure and swelling. Depending on the stage of kidney disease, a doctor might also recommend limiting protein intake, but this varies by individual. Always follow the specific dietary advice of your healthcare team.