Immunoglobulin A

What is the Immunoglobulin A (IgA) test?

The Immunoglobulin A (IgA) test measures the level of IgA antibodies in the blood. IgA is a key antibody involved in mucosal immunity, protecting surfaces such as the gastrointestinal tract, respiratory tract, and genitourinary system.

IgA plays a crucial role in the body’s first line of defence by preventing pathogens from attaching to and penetrating mucosal surfaces. It is found in blood and in secretions such as saliva, tears, and breast milk.

This test is commonly used in immunology to assess immune competence, investigate recurrent infections, and support diagnosis of certain autoimmune or inflammatory conditions.

Why do I need an Immunoglobulin A test?

Abnormal IgA levels can indicate immune deficiency, chronic inflammation, or autoimmune disease. Testing helps clarify whether immune dysfunction may be contributing to symptoms.

You may need an IgA test if you:

• Have recurrent respiratory or gastrointestinal infections
• Experience chronic diarrhoea or gut symptoms
• Have suspected immune deficiency
• Are being screened for coeliac disease
• Have autoimmune or inflammatory conditions
• Have unexplained fatigue or frequent illness
• Are undergoing broader immunoglobulin testing

Symptoms or situations linked to abnormal IgA levels include:

• Recurrent sinus or chest infections
• Chronic gut infections
• Poor response to infections
• Autoimmune disease features
• Allergic or inflammatory symptoms

Benefits of the Immunoglobulin A test

• Assesses mucosal immune defence
  Evaluates a key antibody in frontline immunity.
• Identifies IgA deficiency
  One of the most common primary immunodeficiencies.
• Supports infection risk assessment
  Explains recurrent respiratory or gut infections.
• Essential for coeliac disease screening accuracy
  Ensures reliability of IgA-based tests.
• Clinically recognised immune marker
  Used in NHS and specialist immunology care.
• Useful in autoimmune investigations
  Abnormal levels may reflect immune dysregulation.
• Supports comprehensive immune profiling
  Often tested alongside IgG and IgM.
• Simple blood test
  Requires only a single blood sample.

Step by step – how the test works

You can access Immunoglobulin A testing UK-wide through two options:

1. Clinic appointment
   Attend your nearest UK clinic where a healthcare professional will take your blood sample.
2. At-home or hotel visit (£60 extra)
   A qualified phlebotomist comes to your home or hotel, so you don’t need to travel.

Your sample is analysed in an accredited UK laboratory, and results are delivered securely.

Your results explained

Low IgA levels

May indicate selective IgA deficiency, increasing susceptibility to infections and affecting reliability of certain antibody tests.

Typical UK reference range:

• < 0.7 g/L

Normal IgA levels

Suggest normal mucosal immune function.

Typical UK reference range:

• 0.7–4.0 g/L

High IgA levels

May be seen in chronic inflammation, liver disease, or autoimmune conditions.

Typical UK interpretation:

• > 4.0 g/L

Reference ranges may vary slightly between laboratories.