What are IgG deficiencies?

An IgG deficiency is a health problem in which your body doesn’t make enough Immunoglobulin G (IgG). People with IgG deficiency are more likely to get infections.

When your body feels it is under attack, it makes special proteins called immunoglobulins or antibodies. These antibodies are made by the plasma cells. They are let loose throughout the body to help kill bacteria, viruses, and other germs. The body makes 5 major types of immunoglobulins:

• Immunoglobulin A

• Immunoglobulin G

• Immunoglobulin M

• Immunoglobulin D

• Immunoglobulin E

Immunoglobulin G (IgG) is the most common type. IgG has 4 different subclasses, IgG1— 4. IgG is always there to help prevent infections. It’s also ready to multiply and attack when foreign substances get into the body. When you don't have enough, you are more likely to get infections.

What causes IgG deficiencies?

It’s not known what causes IgG deficiency. However, genetics may play a role. This condition is also thought to be linked to another immunoglobulin deficiency.

What are the symptoms of an IgG deficiency?

Infections that most often affect people with IgG deficiency are:

• Sinus infections and other respiratory infections

• Gastrointestinal infections

• Ear infections

• Pneumonia

• Bronchitis

• Infections that result in a sore throat

• Rarely, severe and life-threatening infections

In some people, infections cause scarring that harms the airways and lung function. This can affect breathing. People with IgG deficiency also often find that pneumonia and the flu vaccines don’t keep them from getting these infections.

How is an IgG deficiency diagnosed?

A blood test that measures immunoglobulin levels can diagnose IgG deficiency. It’s possible to have a normal level of total IgG, so the testing of the IgG subclasses is important. Tests can also be done on saliva and cerebrospinal fluid. But, a blood test is the most common.

How is an IgG deficiency treated?

Treatment depends on how bad your symptoms and infections are. When the symptoms come on later in life, the health problem is harder to manage. The person also tends to have more infections.

If infections are not getting in the way of your daily life, treating them right away may be enough. If you get frequent or severe infections that keep coming back, you may do well with ongoing treatment. This will help to prevent sickness or reduce symptoms or frequency. This may mean taking a daily antibiotic to ward off infections. You may need to alternate between other antibiotics if infections and symptoms still happen.

Some people who suffer from severe infections may be resistant to antibiotic treatment. They may need immunoglobulin therapy to help boost the body’s immune system rather than relying on antibiotics to prevent infections. 

When should I call my healthcare provider?

If you have been diagnosed with IgG deficiency, call your healthcare provider whenever you have signs of infection. This is true even if you just have a cold. 

Key points

• Immunoglobulin G, also known as IgG, is the most common type of IgG deficiencies.

• People with IgG deficiency are more likely to get infections.

• Although it’s not known what causes IgG deficiency, genetics may play a role.

• A blood test that measures immunoglobulin can diagnose this condition.

• When the symptoms come on later in life, the health problem is harder to manage, and the person tends to have more infections.

• Treatment depends on how bad your symptoms and infections are.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

• Know the reason for your visit and what you want to happen.

• Before your visit, write down the questions you want to be answered.

• Bring someone with you to help you ask questions and remember what your provider tells you.

• At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also, write down any new instructions your provider gives you.

• Know why a new medicine or treatment is prescribed, and how it will help you. Also, know what the side effects are.

• Ask if your condition can be treated in other ways.

• Know why a test or procedure is recommended and what the results could mean.

• Know what to expect if you do not take the medicine or have the test or procedure.

• If you have a follow-up appointment, write down the date, time, and purpose for that visit.

• Know how you can contact your provider if you have questions.