What is the Immunoglobulins (IgG, IgM, IgA) test?

The Immunoglobulins test measures the three main antibody classes in the blood: IgG, IgM and IgA. Together, these antibodies represent the core of the body’s humoral immune response.

Each immunoglobulin has a distinct role. IgG reflects long-term immunity and past exposure, IgM indicates early or recent immune activity, and IgA protects mucosal surfaces such as the gut and respiratory tract.

Testing all three provides a comprehensive overview of immune health, helping clinicians assess immune competence, infection history and immune regulation.

Why do I need an Immunoglobulins test?

Abnormal immunoglobulin levels may indicate immune deficiency, chronic infection, autoimmune disease or immune overactivity. Testing helps clarify whether symptoms are immune-related.

You may need an Immunoglobulins test if you:

• Have recurrent or severe infections
• Experience frequent respiratory or gut infections
• Have suspected immune deficiency
• Have autoimmune or inflammatory conditions
• Have unexplained fatigue or prolonged illness
• Are being assessed by an immunologist
• Need baseline immune function assessment

Conditions commonly investigated with this test include:

• Primary or secondary immunodeficiency
• Chronic or recurrent infections
• Autoimmune disease
• Chronic inflammation
• Certain liver or blood disorders

Benefits of the Immunoglobulins test

• Provides a complete immune overview
  Measures the three main antibody classes.
• Identifies immune deficiencies
  Detects low antibody levels affecting infection defence.
• Supports investigation of recurrent infections
  Explains poor immune response.
• Clinically established immune assessment
  Used in NHS and specialist care.
• Useful in autoimmune investigations
  Elevated levels may reflect immune activation.
• Guides further specialist testing
  Helps determine need for subclass or functional tests.
• Suitable for adults and children
  Applied across age groups.
• Simple blood test
  Requires only one blood sample.

Step by step – how the test works

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

1. Clinic appointment
   Choose 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 immunoglobulin levels

May indicate immune deficiency and increased infection risk.

Typical UK reference ranges:

• IgG: < 7.0 g/L
• IgM: < 0.4 g/L
• IgA: < 0.7 g/L

Normal immunoglobulin levels

Suggest intact immune defence and antibody production.

Typical UK reference ranges:

• IgG: 7.0–16.0 g/L
• IgM: 0.4–2.3 g/L
• IgA: 0.7–4.0 g/L

High immunoglobulin levels

May reflect chronic infection, inflammation or autoimmune disease.

Typical UK interpretation:

• One or more immunoglobulins above reference range

Reference ranges may vary slightly between laboratories.