Blood test
Immunoglobulins IgG IgA IgM
Immunoglobulins IgG IgA IgM: what it measures, why a doctor orders it, how to prepare, and what a high or low result can mean - with private and NHS access routes in the UK.
Key facts
At a glance
-
What it measures: the levels of your three main antibody classes - IgG, IgA and IgM.
-
Why it is ordered: to investigate recurrent infections, suspected immune deficiency, and unexplained findings that raise the question of myeloma.
-
No fasting or special preparation is needed for this test on its own.
-
Reference ranges: each class has its own interval, and the pattern across all three is more informative than any single value. Every laboratory publishes its own interval, so the range printed on your report is the one that applies to you.
-
A raised result in one class can reflect chronic infection, liver disease, autoimmunity or - when a single clone dominates - a paraprotein needing electrophoresis. A low result in one or more classes suggests an antibody deficiency, which may explain recurrent chest and sinus infections.
-
Results usually take one to three working days, depending on the laboratory.
The full picture
What this test tells you, and how to get it
The immunoglobulins IgG IgA IgM measures the levels of your three main antibody classes - IgG, IgA and IgM. Doctors most often request it to investigate recurrent infections, suspected immune deficiency, and unexplained findings that raise the question of myeloma. No fasting or special preparation is needed for this test on its own. Each class has its own interval, and the pattern across all three is more informative than any single value, and reference intervals genuinely differ between laboratories, so no single number should be treated as a universal cut-off - your result is always read against the range printed on your own report. Broadly, a raised result in one class can reflect chronic infection, liver disease, autoimmunity or - when a single clone dominates - a paraprotein needing electrophoresis, while a low result in one or more classes suggests an antibody deficiency, which may explain recurrent chest and sinus infections, and either finding is interpreted alongside your symptoms, medication and other results rather than in isolation. Results usually take one to three working days, depending on the laboratory.
In the UK there are two routes to this test. Your NHS GP can arrange it free of charge when it is clinically indicated, though getting the appointment, the blood draw and the follow-up discussion can add days to weeks depending on local demand. Privately, the immunoglobulins IgG IgA IgM can usually be booked within days - through a private GP, a walk-in phlebotomy clinic or a self-request home-testing service - usually with serum electrophoresis when myeloma is the question. A private result still deserves a clinician's interpretation: an isolated number without context is where most confusion about blood tests begins.
A quiet reminder
This guide is for information, not medical advice.
Your own clinician knows your history and can tell you which parts apply to you. Reference ranges vary between laboratories - always read your result against the interval printed on your own report. Next review of this page: 2027-09-27.
Frequently asked
Common questions about Immunoglobulins IgG IgA IgM.
Quick, plain-English answers to what people ask us most.
-
What are immunoglobulins IgG, IgA, and IgM, and what do they show?
Immunoglobulins are antibodies produced by the immune system to fight infection. IgG, IgA, and IgM are three main classes, each with different roles; the blood test measures their total levels to check whether your immune system is functioning normally, over- or under-active.
-
Why would a doctor order this test?
It is used to investigate recurrent or unusual infections, suspected immune deficiency, certain autoimmune conditions, or occasionally as part of investigating unexplained inflammation or specific blood disorders.
-
Do I need to prepare for an immunoglobulin test?
No special preparation, such as fasting, is usually required. It is a standard blood draw.
-
What happens during the test?
A blood sample is taken from a vein and sent to a laboratory to measure the levels of each immunoglobulin class.
-
How long do results take?
Results are typically available within a few days to a week, depending on the laboratory.
-
What do abnormal results mean, and what happens next?
Low levels can suggest an immune deficiency and may prompt further specialist investigation, particularly if you have a history of frequent or unusual infections. High levels can occur with chronic infection, inflammation, liver disease, or certain blood disorders. The specific pattern and your symptoms guide what happens next, so this should always be discussed with your doctor or an immunologist.
-
Is immunoglobulin testing accurate and reliable?
It is a well-established and reliable test, though results are interpreted in the context of your full clinical picture rather than in isolation, since many different conditions can cause raised or lowered levels.
-
How much does private immunoglobulin testing cost, and is it on the NHS?
It is available on the NHS when clinically indicated, and also offered by private clinics, often as part of a broader immune health assessment, with results reviewed by a doctor. Cost varies by provider.
-
How do I book this test privately, and how quickly can I be seen?
Private clinics can typically arrange testing and a doctor's review within a few days.
-
Will I need further tests if my results are abnormal?
Possibly; depending on the pattern of results, further tests such as specific antibody responses, genetic testing, or referral to an immunologist may be recommended to clarify the cause.