A healthy body creates antibodies to fight infections like bacteria, viruses, and fungi. In people with lupus, antibodies mistake healthy tissue for an invader. The antibodies then cause inflammation that damages those tissues.
Unlike many other diseases, no one blood test result means that you have lupus. Instead, your doctor will diagnose you and measure the severity of your disease by looking at:
- Several tests
- Your medical history
- Your current symptoms
Blood tests track the levels of several kinds of antibodies and proteins often found in the body of someone with lupus. This helps your doctor understand how much inflammation is taking place in your body.
Lupus blood tests
The most common blood tests used to test for lupus include:1-3
- Complete blood count (CBC)
- Blood chemistry panel
- Comprehensive metabolic panel
- Immunologic tests
- Positive antinuclear antibody (ANA)
- AVISE® CTD to confirm a positive ANA test
Complete blood count (CBC)
A CBC measures red blood cells, white blood cells, and platelets. An abnormal CBC is common in people with lupus. The CBC may show that you have:1-3
- High white cell count, which means you have an infection or are taking steroids.
- Low white blood cell count (leukopenia), which can be caused by lupus, a virus, or certain drugs.
- Low platelet count (thrombocytopenia), which means that the bone marrow is not making enough platelets or that antibodies are attacking your platelets.
- Low red blood cell count can indicate you have anemia, a vitamin deficiency, or bleeding. About 40 percent of people with lupus become anemic at some point.
Metabolic panel
Inflammation of the heart, blood vessels, lungs, and kidneys can impact how well your body functions in many ways. A comprehensive metabolic panel measures the level of sugar (glucose), minerals, proteins, electrolytes, and fluid balance in the blood. This gives your doctor an indication of:1-3
- Your kidney function
- Your liver function
- How well your metabolism is working
Immunologic tests
Antinuclear antibody (ANA)
Ninety-seven percent of people with lupus test positive for ANAs. However, the ANA test alone is not enough to diagnose lupus. Between 5 and 10 percent of healthy people test positive for ANA. And 20 percent of healthy women will have a weakly positive ANA test.1-3
People with other types of connective tissue diseases might also have a positive ANA test. These include scleroderma and rheumatoid arthritis. Your doctor will look at other test results, any current symptoms, and medical history to diagnose lupus.1-3
If you test positive for ANAs, your doctor may order a more sensitive blood test called the AVISE CTD and an ANA panel. The ANA panel checks for specific antibodies:1-3
- Anti-double-stranded DNA (anti-dsDNA)
- Anti-Smith (anti-Sm)
- Anti-U1RNP
- Anti-Ro/SSA
- Anti-La/SSB
- Anti-nucleoprotein
- Anticentromere
- Antihistone
Your doctor will only give you the ANA test once. If it turns out that you have lupus, your levels of anti-dsDNA will be checked at every visit to monitor your disease.1-3
AVISE® CTD
If your ANA test is positive, your doctor may order the AVISE CTD. This is a blood test that measures the lupus biomarkers called cell-bound complement activation products (CB-CAPs). It can confirm lupus and other autoimmune diseases such as:1-3
- Rheumatoid arthritis
- Sjogren’s syndrome
- Scleroderma
Anti-dsDNA antibody
Less than 1 percent of healthy people produce anti-dsDNA, but 30 percent of people with lupus do. The presence of anti-dsDNA antibodies suggests more serious lupus, especially lupus nephritis (kidney lupus). The tests used to detect anti-dsDNA include:2
- The enzyme-linked immunosorbent assay (ELISA)
- The Crithidia luciliae immunofluorescence test
- Radioimmunoassay
Anti-Sm antibody
The anti-Sm antibody is found in 20 percent of people with lupus. But it is rarely found in healthy people or those with other rheumatic diseases. This means finding anti-Sm can help your doctor be more certain that what you have is lupus. Tests to measure anti-Sm include:2
- ELISA
- Counter immunoelectrophoresis
- Immunodiffusion
- Hemagglutination
Anti-U1RNP antibody
Anti-U1RNP antibodies are found in 1 percent of healthy people but about 25 percent of people with lupus. Anti-U1RNP antibodies are not specific to lupus. These antibodies are also found in people with other rheumatic conditions, such as:2
- Rheumatoid arthritis
- Systemic sclerosis
- Sjogren’s syndrome
- Polymyositis
Anti-Ro/SSA and anti-La/SSB antibodies
Anti-Ro/SSA and anti-La/SSB antibodies are found in 30 percent to 40 percent of people with lupus and Sjogren’s syndrome. Only about 15 percent of healthy people produce these antibodies. People with lupus who have tested negative for ANAs often test positive for anti-Ro/SSA and anti-La/SSB antibodies. These antibodies are linked to extreme sun sensitivity and a subtype of lupus called subacute cutaneous lupus erythematosus.1-3
Anti-histone antibodies
Anti-histone antibodies are most often found in people with drug-induced lupus. But people with systemic lupus erythematosus also sometimes produce these antibodies.1-3
Complement test
Complements are a group of proteins that help regulate the body’s immune response. A blood complement test measures the levels of these proteins. A low level means inflammation is taking place in the body.1-3
Antiphospholipid antibodies
Antiphospholipid antibodies appear in the blood of about 50 percent of people with lupus. People without lupus can also have antiphospholipid antibodies.1-3
The antiphospholipid antibodies most often found are the lupus anticoagulant and anticardiolipin antibody. They can be found together or alone. Other antibodies that may be found include anti-beta 2 glycoprotein 1 and anti-prothrombin.1-3
The number of antibodies found in a person with lupus may increase and decrease over time. People with these antibodies are more likely to experience:1-3
- Miscarriage
- Antiphospholipid antibody syndrome
- Blood clots, which may cause:
- Stroke
- Heart attack
- Other serious complications
Anti-ribosomal P test
Anti-ribosomal P (Rib-P) is a specific biomarker that can be used to detect lupus in people. The Rib-P test is the newest blood test approved by the US Food and Drug Administration. It works by identifying Rib-P autoantibodies. Autoantibodies attack the body’s own proteins. The autoantibodies wrongly see the proteins as foreign invaders. This sets off an immune response.4
The Rib-P blood test was developed to provide earlier diagnoses for people with lupus, especially for those who test negative for ANAs.4
Other blood tests
Depending on your symptoms, your doctor may also order C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR or sed rate) tests. High CRP levels in the blood suggest liver inflammation. ESR measures a protein that makes red blood cells clump together, making it a test for both inflammation and infection.1-3
