Immunoglobulin G4 (IgG4) can be produced in excess levels whenever there is a collection of disorders present within the body. These disorders are immune-related and may cause a wide variety of symptoms, including organs that swell as tumors do, the presence of fibrosis, or inflammation of an organ. The most common reason for this blood test to be orders is the suspicion of pancreatitis, but it may also be caused by other conditions like salivary gland disease, orbital disease, and even pseudo tumors.
Whenever changes in tissue occur that suggest high levels of IgG4 or that a related disease may be present, a medical provider will order this specific blood test. Depending on the results, additional testing may be required or a diagnosis may be made.
What Do My Test Results Mean?
IgG4 test results are typically reported as either “normal” or “abnormal.” Most people will have a normal result from this blood test. When there is an abnormal result due to high levels of IgG4, this can indicate the presence of the suspected related disease.
It is important to note that up to 40% of people with an IgG4 related disease will have normal test results come back.
This is because only 4% of the total IgG that is in the blood is IgG4. Each subclass has unique structural portions that may or may not be related to the conditions that are suspected.
If the blood test does come back as positive, then a tissue biopsy of the organ suspected of being affected is generally taken. Normal values can range from under 19.8 mg/dL to 121 mg/dL depending on the person’s age. Anyone above the age of 18 that has a tissue biopsy that is 100 mg/dL or less of IgG4 will be considered to have a normal result.
Even then, however, high levels of IgG4 create consistency for a suspicion of a related disease, but cannot provide a specific diagnosis.
What Else May Cause High IgG4 Results?
The reason why elevated results do not provide doctors with the ability to make a specific diagnosis is because there are certain health conditions that may also cause alleviated levels. Castleman disease, Churg-Strauss syndrome, and sarcoidosis may also cause these IgG4 blood test results to occur. Even something as simple as an allergic disorder has the capability of causing the issue.
Some doctors may wish to order the blood test to determine if there is a specific allergy to certain foods that someone may be sensitive to when consumed. The issue here is that the immune response of IgG4 isn’t related to the food itself, but to the components that make up the food. From a laboratory standpoint, this makes the test results irrelevant to this issue.
What Is the Concern With This Disease?
When there is an IgG4 related disease present, the concern that doctors have with a positive test result is that the body may be attacking itself for some reason. In the case of pancreatitis, for example, it would mean that the immune system regarding the pancreas as a foreign invader that needed to be destroyed.
The issue is that once it begins, it can become a systemic problem. Instead of attacking just one part of the body, it may wind up attacking the entire body instead. It may be an inherited disorder or it can be something that develops over time.
After confirmation of the issue, a typical treatment option is prednisone. Some medical providers may also consider trying Imuran or other immune suppressant drugs to prevent the body from attacking itself.
The issue with many of the IgG4 related diseases is that many doctors are still in the learning process about this disease. This is especially true with some of the more rare forms of it, such as IgG4 Sclerosing disease. After you receive your test results, you may be referred to a specialist who has more experience with your specific condition.
It is important to remember that when the IgG4 blood test results are explained, not every “normal” test result actually means it is normal.
The high level of error rates with this blood test make it impossible to use as a diagnostic tool. As part of a series of tests to determine why there are high levels of IgG4 in the blood, however, an effective treatment plan can be developed to stop the bothersome symptoms you may be experiencing right now.