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Immunoglobulin A is an antibody that protects your airways and your digestive system against pathogens. A low value can point to an immune system that makes too few antibodies, a high value can point to a condition of the liver or of the immune system.[1]
On this page, you can read what immunoglobulin A is, what the guidelines say about a value that is too low or too high, what affects your value and which other values are best read alongside it.
Also known as: IgA, IgA antibodies, quantitative immunoglobulins. At the lab: IGALG.
Immunoglobulins are also called antibodies. They are proteins your immune system makes against pathogens, such as viruses and bacteria. Your body makes different types, for different places in your body.[1]
An immunoglobulin test usually measures the three main types: IgM, IgG and IgA. IgA protects the organs you breathe with and the organs you eat and digest with.[1]
IgA is not only found in your blood. It is also in saliva, tears, breast milk and the fluid of your airways and stomach.[1]
Your healthcare provider can order this test if you get ill often, especially if the same pathogen is the cause each time. Think of problems with your sinuses, throat and ears, your airways, or diarrhoea.[1]
The test can also be useful if a weak immune system runs in your family. If you have symptoms such as frequent colds or diarrhoea, your healthcare provider can also have the IgA in your saliva measured.[1]
American professional associations for allergy and immunology (AAAAI and ACAAI) wrote a joint practice guideline on diagnosing primary immunodeficiencies and the care that goes with them. They note themselves that not every recommendation suits everyone.[2]
The lab BioProfile works with, Labplusarts, gives no numeric limit for immunoglobulin A: it is a qualitative test. The lab calls a value between the limits normal.[3]
| Range | What it can mean | Who it is for |
|---|---|---|
| No numeric limit (qualitative test)[3] | The lab calls a value within the limits normal | Not specified by the lab |
Source: Labplusarts, reference value for immunoglobulin A (IGALG), as the lab uses it.[3]
A low value of one or more immunoglobulins can point to something that makes your body lose protein or absorb too little. Think of a kidney condition, severe burns, a gut that absorbs food poorly or malnutrition. It can also point to something that makes your body produce fewer antibodies, such as kidneys that no longer work properly or an inherited condition of the immune system.[1]
A high value can point to a condition in which the immune system attacks the body's own cells, a liver condition, a pathogen that stays in your body for a long time, or certain conditions of the bone marrow, the blood or the immune system. Those antibodies often do not work properly, so you can get ill often even with a high value. An abnormal value does not always mean there is something that needs care. Discuss your result with your healthcare provider.[1]
BioProfile is working on its own zones for each value, from risk to optimal. A doctor reviews those zones before they appear in your result.
Some medicines can affect the result. Tell your healthcare provider which medicines you take before the test, but do not stop taking them without talking to them first.[1]
Antibodies are proteins. Anything that makes your body lose protein or take in too little nutrition, such as malnutrition or a gut that absorbs food poorly, can lower your value.[1]
You don't need to do anything special to prepare for this test.[1]
Immunoglobulin A is included in BioProfile 121 and 150.[4]
The BioProfile editorial team wrote this page on 10 October 2026 from the sources below, which we read on 10 October 2026. Every number on this page appears in one of those sources, with that source's number next to it. An expert has yet to check this page; after that check, the expert's name and the date of the check will appear at the top. This page offers explanation, not a diagnosis. Discuss a value outside the range with your GP.
