Patient Articles

Immunologic Blood Tests

Used in the Diagnosis and Treatment of Rheumatic Diseases

The immune system normally creates antibodies to ward off any invader. Immunologic tests can look for these antibodies. When the immune system causes auto immune diseases, it may make certain types of antibodies that can show the disease your immune system may be causing or fighting.

Anti-nuclear Antibody (ANA)

Many people with an autoimmune disease have higher levels of ANA in their blood. Some people with ongoing infections or tumors also have high ANA levels. Older patients may have elevated ANA levels and yet be healthy. This is referred to sometimes as a false positive test.

Anti-dsDNA Antibody & Anti-Sm Antibody

People with lupus often have these antibodies in their blood. Anti-dsDNA can also show that someone with lupus is prone to kidney disease.

Anti-SSA Antibody & Anti-SSB Antibody

These antibodies are often found in the blood of someone with lupus or Sjögren’s syndrome. If you have rheumatoid arthritis, you can also get Sjögren’s syndrome. Therefore, you may need to have an anti-SSA or anti-SSB test.

Mothers who are pregnant and who have high levels of these antibodies may have babies who have problems with their heart rhythm. That is because these antibodies can cross from the mother’s circulation, over the placenta, and get into the baby in the uterus. They may affect the tissues that are part of the conducting system of the baby’s heart.

Anti-scleroderma Antibody & Anti-centromere Antibody

Your doctor may order one of these tests to see whether you have scleroderma, or a related condition called the CREST syndrome.

Anti-Jo-1 Antibody

Having this antibody shows that you may have a special type of myositis, called polymyositis. This antibody is especially common in people with polymyositis and lung problems.

Anti-U1-RNP Antibody

You may need to get this test, if you have symptoms typical for several different autoimmune diseases. Patients with lupus may have this antibody. There is also a disease called mixed connective tissue disease (MCTD). Patients with MCTD have symptoms of a number of diseases, including lupus, scleroderma, and myositis. They often have very high levels of this antibody.

Rheumatoid Factor (RF)

Most people with rheumatoid arthritis have RF in their blood. If you have high levels of RF, you may get worse quickly. Therefore, you may need to get more serious medications early on. There are many patients who have a positive RF test who do not have RA. Patients with other connective tissue diseases such as SLE may have a positive RF. Patients with chronic infections may have a positive RF, and older patients may have a positive RF as well and be healthy. In that case, we call the result a false positive.

Cyclic Citrullinated Protein (CCP)

This is another test used to see whether you have rheumatoid arthritis. When this test is positive, it almost always means the patient has RA, and perhaps a greater likelihood of severe disease. Therefore, you may need to get more serious medications.

Complement Tests (C3, C4, CH50)

These tests can show whether you have an ongoing autoimmune disease. It is often used in people who may have lupus, especially lupus together with kidney problems.

ANCA Tests

These tests may help in the diagnosis of some types of vasculitis, and to monitor the activity of vasculitis.

Anti cardiolipin or anti phospholipid antibody tests

These antibodies may cause an increased chance of blood clots, because they may affect how platelets behave. They are common in lupus patients, but may also occur in other auto immune diseases, or by themselves. Patients who have these types of antibodies may have a false positive blood test for syphilis. By doing the right types of tests, doctors can determine if a positive syphilis test means an infection or is due to autoimmunity.