When your body feels it is under attack, it makes proteins called antibodies. They are also called immunoglobulins. The plasma cells in your blood make them. They help kill bacteria, viruses, and other germs.

There are several types of immunoglobulins. Immunoglobulin G (IgG) is the most common one in the blood. It helps prevent infections. IgG deficiency is when the body doesn't make enough IgG.

IgG is ready to attack when things like viruses get into the body. When you don't have enough IgG or it's not working right, you are more likely to get infections.

IgG deficiency may be primary or secondary. Researchers don't know what causes primary IgG deficiency. Genes may play a role. Secondary IgG deficiency may be caused by:

• Aging.
• Poor nutrition.
• Certain cancers or chemotherapy medicines.
• Taking corticosteroid medicine for a long time.
• Infections, such as HIV.

People with IgG deficiency get these kinds of infections more often:

• Sinus infections and other respiratory infections
• Digestive tract infections
• Ear infections
• Pneumonia
• Bronchitis that keeps coming back, which can lead to permanent lung damage
• Infections that cause a sore throat
• Severe and life-threatening infections (rare)

In some people, infections cause scarring in the airways. This harms how the lungs work. It can affect breathing.

People with IgG deficiency often find that pneumonia and flu vaccines don't prevent these infections well.

A blood test is the most common way to diagnose IgG deficiency. The blood test measures immunoglobulin levels. In some cases, tests can be done on saliva and cerebrospinal fluid (CSF). Or your doctor will see how your immune system responds after getting a vaccine. You may see a doctor called an immunologist.

Treatment depends on how bad your infections are. Later in life, the health problems may be harder to manage. You may have more infections.

If infections don't harm your daily life, treating them right away may be enough. If you get many or severe infections, you may need other treatment. This may be a daily antibiotic medicine. It will help to prevent sickness, or it can reduce symptoms or how often they happen. You may need to switch antibiotic medicine if infections still happen.

For some people who have severe infections, antibiotics don't work well enough. They may need immunoglobulin therapy. This helps boost their immune system. The therapy contains IgG antibodies. They come from healthy donors with normal immune systems. The medicine is given through an I.V. (intravenous). Or it may be given as an infusion just under the skin (subcutaneous). In some cases, you can give yourself the medicine at home.

If you have IgG deficiency, call your doctor when you have signs of infection. This is true even if you just have a cold or other minor symptoms.

• Antibodies help fight infection. Immunoglobulin G (IgG) is normally the most common antibody in the blood. People with IgG deficiency don't have enough of it.
• People with IgG deficiency are more likely to get infections.
• Genes may be part of the cause of primary IgG deficiency.
• Treatment depends on how bad your infections are. It can range from treating infections early, to taking daily antibiotic medicine. Or you may have immunoglobulin infusions through an I.V. or just under the skin (subcutaneous).

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

• Know the reason for your visit and what you want to happen.
• Before your visit, write down questions you want answered.
• Bring someone with you to help you ask questions and remember what your doctor 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 directions your doctor 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 doctor if you have questions.