IgA
Also known as: Immunoglobulin A
What Does IgA Measure?
IgA (Immunoglobulin A) is a type of antibody protein produced by plasma cells and found primarily in body secretions such as saliva, tears, breast milk, and mucus lining the digestive and respiratory tracts. A blood test measuring IgA quantifies the concentration of this antibody in your serum, reflecting the health and activity of your mucosal immune system. IgA serves as the first line of defense at mucosal surfaces, neutralizing pathogens before they can invade deeper tissues.
Why Does IgA Matter?
IgA levels provide critical insight into the functioning of the immune system, particularly mucosal immunity. Abnormally low IgA (IgA deficiency) is the most common primary immunodeficiency disorder and can lead to recurrent sinus, lung, and gastrointestinal infections. Elevated IgA levels can signal chronic infections, autoimmune conditions, liver disease, or certain cancers such as IgA myeloma. Measuring IgA is also essential for diagnosing conditions like celiac disease (via anti-tissue transglutaminase IgA antibodies) and IgA nephropathy, a kidney condition triggered by IgA deposits. Clinicians frequently order IgA as part of an immunoglobulin panel alongside IgG and IgM to get a complete picture of immune health.
Normal Ranges
Males
70–400 mg/dL
Females
70–400 mg/dL
Children
Varies by age: newborns 0–11 mg/dL, rising gradually to adult levels by age 10–12
Causes of High Levels
- Chronic infections (e.g., recurrent respiratory or gastrointestinal infections stimulating sustained immune response)
- Autoimmune diseases such as rheumatoid arthritis, lupus, or inflammatory bowel disease
- Liver disease including cirrhosis or chronic hepatitis, which impairs IgA clearance
- IgA myeloma (a plasma cell cancer producing excessive monoclonal IgA)
- IgA nephropathy (Berger's disease), where IgA deposits accumulate in the kidneys
- Celiac disease with active gluten exposure triggering elevated mucosal immune response
Causes of Low Levels
- Selective IgA deficiency, the most common primary immunodeficiency, often genetic in origin
- Common variable immunodeficiency (CVID), a broader antibody deficiency disorder
- Medications such as corticosteroids, immunosuppressants, or certain anticonvulsants (e.g., phenytoin)
How to Improve Your IgA
Diet
- Consume a diverse, fiber-rich diet with plenty of fruits, vegetables, and whole grains to support gut microbiome diversity and mucosal immunity
- Include fermented foods such as yogurt, kefir, sauerkraut, and kimchi, which contain probiotics that stimulate IgA secretion in the gut
- Ensure adequate protein intake (0.8–1.2 g/kg body weight) to provide amino acids needed for antibody synthesis
- Increase consumption of zinc-rich foods such as oysters, red meat, pumpkin seeds, and legumes, as zinc is essential for immune cell development
- Limit ultra-processed foods, refined sugars, and alcohol, which can suppress immune function and disrupt gut barrier integrity
Supplements
- Probiotics (Lactobacillus rhamnosus GG or Bifidobacterium longum, 5–20 billion CFU/day) have been shown to enhance secretory IgA levels in the gut
- Vitamin D3 (1,000–2,000 IU/day) supports B-cell function and IgA class switching, particularly in those who are deficient
- Zinc (8–11 mg/day from diet, or up to 25 mg/day supplemental under medical supervision) is critical for plasma cell activity and antibody production
- Colostrum supplements (500–3,000 mg/day) are a natural source of IgA and may help bolster mucosal immunity in deficient individuals
Related Biomarkers
Frequently Asked Questions
What does it mean to have low IgA levels?
Low IgA levels, especially when below 7 mg/dL, is called selective IgA deficiency — the most common primary immune deficiency, affecting about 1 in 300 to 500 people. Many people have no symptoms, but some experience recurrent respiratory or gastrointestinal infections, allergies, or autoimmune conditions. If you have low IgA, you should also be aware that IgA-based celiac tests (like anti-tTG IgA) can give false-negative results, so your doctor may need to order alternative tests.
Can IgA levels be used to diagnose celiac disease?
Yes, IgA-based antibody tests are central to celiac disease diagnosis. The most commonly used is anti-tissue transglutaminase IgA (anti-tTG IgA), which detects the immune response to gluten in celiac patients. However, because about 2–3% of celiac patients also have IgA deficiency, doctors typically measure total serum IgA alongside the anti-tTG IgA. If total IgA is low, the test may give a false-negative result, and IgG-based tests should be used instead.
What is IgA nephropathy and how does IgA relate to it?
IgA nephropathy, also called Berger's disease, is the most common form of primary glomerulonephritis worldwide. It occurs when abnormal IgA antibodies deposit in the kidneys' filtering units (glomeruli), triggering inflammation and progressive kidney damage. People with this condition often have elevated serum IgA levels, though diagnosis is confirmed by a kidney biopsy showing IgA deposits. Symptoms can include blood in the urine, protein in the urine, and, in advanced cases, high blood pressure and reduced kidney function.