Immunoglobulin A (IgA) nephropathy is a kidney disease characterized by the abnormal buildup of IgA antibodies within the kidneys. This condition can interfere with the kidneys’ ability to filter waste from the blood, potentially leading to kidney damage over time. This article provides a clear understanding of IgA nephropathy, its prevalence, and its general signs and outlook.
What is IgA Nephropathy
IgA is an antibody that forms part of the body’s immune system, protecting against infections. In IgA nephropathy, abnormally formed IgA antibodies deposit in the kidneys’ tiny filtering units called glomeruli. This deposition triggers inflammation and can lead to damage within these structures.
The kidneys are responsible for filtering waste products and excess water from the blood, which are then excreted as urine. When the glomeruli are damaged by IgA deposits, their filtering ability is impaired, allowing blood and protein to leak into the urine. This condition is also known as Berger’s disease and is classified as a form of glomerulonephritis, which causes inflammation of the kidney’s filters.
How Common is IgA Nephropathy
While uncommon in the general population, IgA nephropathy is one of the most frequently diagnosed forms of primary glomerulonephritis globally. The worldwide incidence is estimated to be 2.5 cases per 100,000 people annually. In the United States, recent studies indicate an incidence rate of approximately 1.4 cases per 100,000 person-years.
The prevalence of IgA nephropathy shows variations across different geographical regions and ethnic groups. It is observed more frequently in Asian populations, with higher incidence rates in Asian/Pacific Islander individuals in the U.S. and Japan. In contrast, Caucasian populations tend to have lower rates. These differences are partly attributed to genetic factors and variations in healthcare practices, such as routine urine screening programs common in some Asian countries. The condition also appears more often in males and typically affects young adults, between the ages of 10 and 40.
Signs and Outlook of IgA Nephropathy
IgA nephropathy often progresses silently, with many individuals showing no obvious symptoms for years. When signs do emerge, they frequently include visible blood in the urine, a condition known as hematuria. Foamy urine, indicating the presence of protein (proteinuria), and swelling in the legs, ankles, or face due to fluid retention, are also common indicators. These urinary changes can sometimes be noticed following common infections, such as a cold or sore throat.
A definitive diagnosis of IgA nephropathy typically requires a kidney biopsy, where a tissue sample is examined for IgA deposits and kidney damage. The long-term outlook for individuals with IgA nephropathy varies. Some individuals may maintain stable kidney function for extended periods, while others experience a progressive decline in kidney function.
Approximately one in four adults with IgA nephropathy may progress to end-stage renal disease (ESRD), where the kidneys no longer function adequately, often within 10 to 20 years of diagnosis. Factors that can accelerate this progression include high amounts of blood or protein in the urine, uncontrolled high blood pressure, and existing scarring within the kidney’s filters. Regular monitoring of kidney function is an important part of managing this condition.