Immunoglobulin A, Qn, Serum

Immunoglobulin A (IgA) is an antibody blood protein that’s part of your immune system. Your body makes IgA and other type of antibodies to help fight off sickness. Having an IgA deficiency means that you have low levels of or no IgA in your blood. 

IgA is found in mucous membranes, mainly in the respiratory and digestive tracts. It is also found saliva, tears, and breastmilk. A deficiency seems to play a part in asthma and allergies. Researchers have also linked IgA deficiency to autoimmune health problems. These are health problems that cause your body’s immune system to attack your body by mistake.

Some people are born with low or absent levels of IgA. Low levels occur in some types of leukemia, kidney damage (nephrotic syndrome), a problem with the intestines (enteropathy), and a rare inherited disease that affects muscle coordination (ataxia-telangiectasia). This increases the chances of developing an autoimmune disease. Patients with low IgA are at some increased risk of developing severe reactions after receiving blood products.

Possible symptoms:

Most people with an IgA deficiency do not have any symptoms. About 1 in 4 to 1 in 2 people with selective IgA deficiency will be affected. Some people with an IgA deficiency are more likely to get frequent infections. These can include sinus, lung, and digestive infections. Some people with IgA deficiency also are more likely to have allergies, and digestive and autoimmune problems such as celiac disease or lupus.

Elevated IgA levels are nonspecific, but can be seen in pulmonary and gastrointestinal inflammatory diseases, some autoimmune conditions, liver disease, and plasma cell disorders.

IgA antibodies are found in the mucous membranes of the lungs, sinuses, stomach, and intestines. They're also in fluids these membranes produce, like saliva and tears, as well as in the blood.

Some possible causes of high levels of one or more immunoglobulins are:

- An autoimmune disease
- Hepatitis
- Cirrhosis
- Chronic infection/inflammation
- IBD
- Diabetes and diabetic complications
- Obesity / Metabolic syndrome
- Alcoholism
- IgA nephropathy or Berger's disease
- Rheumatoid arthritis with high titres of rheumatoid factor
- SLE (occurs in some patients)
- Sarcoidosis (occurs in some patients)
- Wiskott-Aldrich syndrome

High levels can be due to certain cancers. These cancers often cause a very high level of one type of immunoglobulin and low levels for the other types:

- Multiple myeloma
- Chronic lymphocytic leukemia (CLL)
- Lymphoma
- Waldenstrom macroglobulinemia

If your immunoglobulin levels are not normal, it does not always mean you have a condition that needs treatment. Certain medicines can affect your results. If you have questions about your results, talk with your healthcare provider.