The first step in diagnosing an immune deficiency is a good evaluation.
If your doctor suspects that your immune system is not working properly, or if you are frequently sick, you may be referred to an immunologist (immune system specialist who is also an allergist by training). An immunologist will then help with your diagnosis and treatment.
Evaluation of the immune system may include:
At the time of the evaluation, your doctor will ask questions about your health. Frequent or unusual infections, prolonged diarrhea and poor childhood growth are some symptoms of a possible immune deficiency. Because some immune deficiencies run in families, you will be asked questions about your family's health. You will also have a complete check-up.
If an immune deficiency is suspected, a series of blood tests and vaccines may be done.
Blood tests will show if any part of the immune system is missing or not working properly. For example, blood tests will reveal if there are any cells lacking from a complete immune system or if the cells are present but lack adequate amounts for the system to function effectively.
Vaccines may be given to test the immune system's response. In the normal immune system, antibodies against the organisms in the vaccine are formed in the blood. If antibodies to the vaccine are not found a few weeks after the vaccine is given, an immune deficiency may exist. A lack of specific antibodies demonstrates an inability to produce and maintain an effective defense against infection. Antibodies are highly sensitive "scout" molecules that fight infection.
The physician may order additional tests to confirm the diagnosis.