Immunoglobulin A nephropathy, also known as IgAN or Berger’s disease, is a chronic kidney condition. It involves damage to the kidneys’ filtering units, the glomeruli. This damage occurs due to the accumulation of immunoglobulin A (IgA) within these filters. The disease can gradually impair the kidneys’ ability to filter waste from the blood.
The Underlying Cause of IgAN Disease
Immunoglobulin A normally functions as an antibody to combat infections. In IgAN, however, an abnormal form of IgA is produced. This defective IgA then forms clusters or immune complexes that travel through the bloodstream and can become trapped in the kidney’s glomeruli.
The buildup of these abnormal IgA deposits triggers an immune response within the glomeruli, leading to inflammation and damage to the delicate filtering structures. While the precise trigger for this abnormal IgA production remains unclear, IgAN is considered an autoimmune condition where the immune system mistakenly attacks its own tissues. Genetic factors often predispose individuals to IgAN, as it can run in families. Environmental factors, such as infections, may also influence the disease’s development and progression.
Recognizing Signs and Symptoms
One of the most common signs of IgAN is hematuria (blood in the urine). Visible blood may appear, making the urine pink, dark brown, or cola-colored, often occurring during or shortly after a respiratory infection. Alternatively, blood in the urine may only be detectable under a microscope (microscopic hematuria), often discovered during routine tests.
Another indication of kidney damage is proteinuria (protein in the urine). This can make the urine appear foamy. When the kidneys’ filters are compromised, they fail to retain proteins, leading to their excretion in urine. Impaired kidney function can also result in fluid retention, causing edema, commonly observed in the hands, feet, ankles, and sometimes around the eyes. High blood pressure (hypertension) is also a frequent symptom, as damaged kidneys struggle to regulate fluid balance and blood vessel constriction.
The Diagnostic Process
Diagnosis of IgAN often begins with non-invasive tests that suggest kidney involvement. A urinalysis often checks for blood and protein in the urine, which are early indicators of glomerular injury. Blood tests are also conducted to assess kidney function, measuring creatinine levels and estimating the glomerular filtration rate (eGFR). Creatinine is a waste product that healthy kidneys filter efficiently, so elevated levels can indicate impaired function.
While these tests can point toward kidney disease, confirming IgAN requires a kidney biopsy. This involves taking a small tissue sample from the kidney using a special needle. The tissue is then examined under a microscope by a pathologist. Pathologists specifically look for characteristic granular deposits of IgA within the mesangium to confirm IgAN.
Treatment and Management Strategies
The management of IgAN involves supportive care and medications to slow disease progression. Lifestyle adjustments are part of supportive care, including controlling blood pressure and limiting dietary sodium intake to help reduce fluid retention and kidney strain. Maintaining a healthy weight and avoiding smoking are also recommended to promote overall kidney health.
Medications are important in treatment. Angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) are commonly prescribed to lower blood pressure and reduce protein in the urine. These medications help protect the kidneys from further damage by relaxing blood vessels and decreasing pressure within the glomeruli. For individuals experiencing more rapid disease progression or significant proteinuria, corticosteroids or other immunosuppressants may be considered to reduce inflammation and immune activity. Newer, targeted therapies are also becoming available, focusing on specific pathways involved in IgAN’s development.
Long-Term Progression and Outlook
The course of IgAN can vary among individuals. Many people with IgAN maintain stable kidney function for extended periods without experiencing severe complications. For others, however, the disease can be progressive, leading to a gradual decline in kidney function over time.
Several factors influence the long-term outlook, including the degree of proteinuria and how well blood pressure is controlled. Higher levels of proteinuria and uncontrolled hypertension are often associated with a greater risk of disease progression. For some patients, IgAN can advance to end-stage renal disease (ESRD), where the kidneys no longer function adequately to support the body’s needs. At this stage, individuals typically require life-sustaining treatments such as dialysis or a kidney transplant.