Immunoglobulin A (IgA) is a protein in the body’s immune system that defends against various threats. Assessing IgA levels provides insights into the immune system’s function, especially at the body’s entry points, making it an important part of health evaluation.
Understanding Immunoglobulin A
Immunoglobulin A is an antibody, a protein produced by the immune system to identify and neutralize foreign substances like bacteria, viruses, and toxins. It functions as a first-line defense, primarily guarding the body’s mucosal surfaces, such as the linings of the digestive, respiratory, and urogenital tracts. IgA prevents pathogens from attaching to and entering host cells, effectively trapping them within mucus or other bodily fluids for removal.
This antibody is present in various external secretions like saliva, tears, sweat, and breast milk, as well as in the blood. IgA exists in two main forms: serum IgA, found predominantly in the bloodstream, and secretory IgA (sIgA), the primary form in mucosal secretions. Secretory IgA is robust due to a component that protects it from degradation by enzymes in harsh environments, like the gastrointestinal tract. This allows sIgA to maintain its protective function, acting as a barrier against invading microbes.
Establishing Normal IgA Levels
Determining a “normal” IgA level is not a single, universal value, as reference ranges differ between laboratories due to variations in testing methods and equipment. IgA levels also fluctuate based on personal factors, with age being a significant influence. Levels are typically lower in children, gradually increasing as the immune system matures, and may show a slight decline in older age.
For adults, serum IgA concentrations often fall within a range of 70 to 400 milligrams per deciliter (mg/dL). These figures are general guidelines; individual test results must be compared against the specific reference range provided by the performing laboratory. Only a healthcare professional can accurately interpret these results within the context of a person’s complete medical history and overall health.
Conditions Linked to High IgA Levels
Elevated IgA levels can signal an intensified immune response, often indicating the body is actively combating an infection or experiencing chronic inflammation. Chronic infections are a common cause, as the immune system continuously produces antibodies to fight persistent pathogens. For instance, chronic Helicobacter pylori infections can lead to elevated IgA, associated with gastrointestinal symptoms.
Autoimmune and inflammatory conditions also frequently present with high IgA. Inflammatory bowel diseases (IBD), such as Crohn’s disease and ulcerative colitis, can cause elevated IgA levels, reflecting ongoing inflammation. Rheumatoid arthritis (RA) may also be associated with increased IgA, sometimes indicating more severe disease. Celiac disease, an autoimmune condition triggered by gluten, often results in elevated IgA antibodies as the immune system mistakenly attacks the body’s own tissues.
Liver diseases, especially liver cirrhosis, are another cause of elevated IgA, often reflecting bacterial translocation from the gut to the liver. Additionally, certain cancers, such as multiple myeloma and lymphoma, can lead to high IgA levels. In IgA multiple myeloma, abnormal plasma cells produce excessive monoclonal IgA. Lymphomas, including some non-Hodgkin’s types, can also be associated with elevated IgA. High IgA levels are characteristic of Wiskott-Aldrich syndrome, a rare genetic disorder affecting the immune system, where IgA can be significantly elevated.
Conditions Linked to Low IgA Levels
Lower-than-normal IgA levels can compromise the body’s first line of defense, potentially increasing susceptibility to certain health issues. The most common primary immunodeficiency is selective IgA deficiency (SIgAD), characterized by very low or undetectable IgA with otherwise normal levels of other immunoglobulins. Many individuals with SIgAD experience no symptoms, but others may face recurrent infections, particularly in the respiratory and gastrointestinal tracts, such as ear infections, sinusitis, bronchitis, and pneumonia. These individuals may also have an increased risk of developing autoimmune conditions like rheumatoid arthritis, celiac disease, and lupus, as well as allergies and asthma.
Certain medications, including some immunosuppressants and anti-seizure drugs, can suppress IgA production. In some cases, discontinuing the medication may reverse the deficiency. Low IgA can also be a feature of other, rarer primary immunodeficiencies, such as Ataxia-telangiectasia, a genetic disorder affecting multiple body systems.
Waldenström’s macroglobulinemia, a rare type of non-Hodgkin lymphoma, frequently involves low levels of IgA and IgG. This hypogammaglobulinemia, or general reduction in immunoglobulin levels, can also be present in other primary or secondary immunodeficiencies, making individuals more vulnerable to infections. The implications of low IgA stem from its role in mucosal immunity; a deficit means a weakened barrier against pathogens at the body’s entry points, potentially leading to chronic or more severe infections.
What Your IgA Results Mean
An IgA test provides a snapshot of your immune system’s humoral response. An abnormal IgA level, whether high or low, is not a definitive diagnosis but an indicator that prompts further investigation. It suggests your immune system might be overactive, underactive, or responding atypically to an underlying condition.
Interpreting IgA results requires a comprehensive approach by a healthcare professional. They will consider your symptoms, medical history, physical examination findings, and other diagnostic tests to understand the full clinical picture. Self-interpreting these results can lead to unnecessary anxiety or misdiagnosis. If you receive abnormal IgA test results, consulting with your doctor is the appropriate next step to determine the cause and discuss any necessary management or follow-up.