Autoimmune diseases are a broad category of diseases that occur when the immune system attacks healthy cells in the body. Although there are many symptoms that are used to help diagnose these conditions, your doctor may also use blood tests to help reach a diagnosis.

SED-Rate And CRP

Elevated inflammation levels can be the result of any number of acute or chronic conditions. Since autoimmune diseases cause your immune system to be hyperactive, inflammation levels usually rise, as well. There are two common tests to determine inflammation in the body, the erythrocyte sedimentation rate (ESR) (also called the SED rate) and the c-reactive protein (CRP).

The ESR measures how rapidly red blood cells fall to the bottom of the collection tube. As the rate increases, it is indicative of inflammation throughout the body. The CRP is another test of inflammation that works differently. Your liver makes c-reactive protein because of inflammation. Higher levels of this protein are also an indication of systemic inflammation. Both tests can be elevated for other reasons, such as an infection.

Antinuclear Antibody (ANA) Test

The antinuclear antibody (ANA) test is frequently used in the diagnosis of some autoimmune disease. Sometimes a more sophisticated form of the test is used to determine the specific type of ANAs. ANAs are a special type of antibody that is produced when your immune system attacks your own tissues. Although ANA can be found in several autoimmune diseases, it is frequently associated with lupus.

Higher levels of ANA are generally consistent with a more severe disease process. Although it is uncommon, someone with lupus may test ANA-negative or whether they test positive or negative may fluctuate throughout the years. There are many subtypes of ANA, with most of them considered highly consistent with other autoimmune diseases. For example, antinuclear ribonucleoprotein (anti-nRNP) tends to correlate with the presence of mixed connective tissue disorder, whereas anti-Ro/anti-La antibodies are often seen in Sjogren's syndrome.

RF And Anti-CCP

The level of rheumatoid factor (RF) is frequently used to diagnose rheumatoid arthritis (RA). Much like other tests, RF levels can be elevated in several other diseases or can be negative in people who actually have the disease (seronegative RA). RF is another type of protein that is created when your immune system attacks healthy cells. People with Sjogren's syndrome may also have high RF levels.

The anti-cylic citrullinated protein (anti-CCP) test is another test of a protein that is commonly found in people with RA, but like the RF, it can be negative in people with RA. Anti-CCP is more often associated with RA, but can also be high in people with other autoimmune diseases like lupus.

There are many blood tests that are frequently used together with symptom presentation to help diagnose various autoimmune diseases. Once the condition is diagnosed, regular blood tests may be used to help monitor the disease and determine whether treatment is effective. Talk to a blood-testing lab if you need one of these tests.