Berger’s Disease is the common name for Immunoglobulin A nephropathy (IgAN), a chronic kidney disease affecting the filtering units of the kidneys, called glomeruli. The IgA immune protein accumulates within these filters, causing inflammation and damage that slowly impairs the kidneys’ ability to cleanse the blood. IgAN is the most frequent form of primary glomerulonephritis. While the disease course varies widely, it can ultimately lead to a decline in kidney function and, for some, kidney failure.
Understanding the Pathogenesis
The mechanism behind IgA nephropathy involves an abnormality in the body’s immune system concerning the IgA1 antibody. In this condition, the IgA1 protein is improperly formed, lacking a full complement of galactose sugar molecules in a specific region. This results in “galactose-deficient IgA1” (Gd-IgA1).
The immune system recognizes Gd-IgA1 as abnormal, prompting the body to produce other antibodies, primarily IgG, to target it. These components bind together to form circulating immune complexes. These complexes travel to the kidneys and become trapped within the mesangium, the central tissue of the glomeruli.
The trapped immune complexes activate local mesangial cells, triggering inflammation and injury. This continuous inflammatory response releases signaling molecules, leading to scarring and sclerosis of the glomeruli. Genetic predisposition and environmental factors, such as infections, are thought to play a role by influencing abnormal IgA production or acting as disease triggers.
Recognizing the Clinical Signs
The presentation of IgA nephropathy is highly variable, ranging from no noticeable symptoms to significant kidney dysfunction. The most common initial manifestation is hematuria, or blood in the urine. Visible hematuria (gross hematuria) often appears as pink, tea-colored, or cola-colored urine. These episodes frequently occur within a day or two of a respiratory or gastrointestinal infection.
Many individuals only experience microscopic hematuria, where blood cells are detectable through a lab test. Proteinuria, or protein leaking into the urine, is another common sign indicating glomerular damage. Excessive protein leakage may cause the urine to appear foamy.
As kidney function declines, high blood pressure is a frequent finding because the damaged kidneys struggle to maintain proper fluid balance. Swelling, known as edema, often affects the hands, feet, and ankles. Other general symptoms can include persistent fatigue and pain in the sides or lower back.
Confirming the Diagnosis
Identifying IgA nephropathy typically involves routine laboratory tests checking for signs of kidney injury. Urinalysis detects the presence of red blood cells (hematuria) and protein (proteinuria) in the urine. The amount of protein is often quantified using a urine protein-to-creatinine ratio or a 24-hour urine collection.
Blood tests assess how effectively the kidneys filter waste. These tests measure serum creatinine levels, a waste product that builds up when kidney function is impaired. An estimated Glomerular Filtration Rate (eGFR) is calculated from the creatinine level to measure overall kidney function.
The definitive way to confirm a diagnosis of IgA nephropathy is through a kidney biopsy. During this procedure, a small sample of kidney tissue is collected and examined under a microscope. The diagnosis is confirmed by finding IgA deposits within the mesangium, which is the pathological hallmark of the disease. The biopsy also allows for staging the disease severity based on the extent of inflammation and scarring.
Managing Disease Progression
The management of IgA nephropathy focuses on slowing the rate of kidney damage and controlling associated complications. Supportive care is the foundation of treatment, centered on reducing proteinuria and maintaining healthy blood pressure levels. Angiotensin-converting enzyme (ACE) inhibitors or Angiotensin Receptor Blockers (ARBs) are the preferred first-line medications for this purpose.
These medications are beneficial because they lower blood pressure and directly reduce protein leakage into the urine, providing a protective effect to the kidney. Lifestyle modifications are also integral to supportive care. These include adopting a low-sodium diet and managing weight, which assists in blood pressure control.
For patients with persistent and significant proteinuria despite optimal supportive care, immunosuppressive therapies, such as corticosteroids, may be considered. Glucocorticoids are reserved for high-risk cases where kidney function is preserved. Their use is carefully weighed against potential side effects and they are typically given for a limited duration. In cases of advanced kidney failure, the only available treatments are dialysis or a kidney transplant.