Blood tests can help diagnose and monitor systemic lupus erythematosus (SLE). These include tests for antinuclear antibodies (ANAs), anti-double-stranded DNA (anti-dsDNA) antibodies, and more.

While doctors cannot use laboratory tests alone to diagnose lupus, blood tests are an important part of the process for confirming the diagnosis.

Blood tests can also help monitor lupus. This can be useful for assessing whether current treatments are effective in managing the chronic condition.

Read on for more information about the role of blood tests in diagnosing and monitoring lupus.

Doctors may order various blood tests to help diagnose lupus.

Antibody tests

Antibody tests check for the presence of certain antibodies. Lupus causes the body to make antibodies, known as autoantibodies. These mistakenly attack the body’s healthy cells.

Around 97% of people with lupus have antinuclear antibodies (ANAs). However, ANAs can also be present with other conditions, so a positive test for ANAs does not always indicate lupus.

Around half of people with lupus have anti-double-stranded DNA (anti-dsDNA) antibodies. However, you can still have lupus even if blood tests are negative for anti-dsDNA antibodies.

Other antibodies that may indicate lupus include:

  • histone antibodies, which attack the protein histone, an important part of chromosomes
  • phospholipid antibodies (aPLs), which attack phospholipids, part of cell membranes
  • ribonucleoprotein antibodies (anti-RNPs), which attack ribonucleoprotein, a protein that helps control chemical activity in cells
  • anti-Smith (anti-Sm) antibodies, which are present in around 3 in 10 cases of lupus
  • anti-Ro/SSA and anti-La/SSB, which may be present in cutaneous lupus, or lupus affecting the skin

Other blood tests

Other blood tests that can help diagnose lupus include:

  • Complete blood counts: Complete blood counts check the levels of red blood cells, while blood cells, and platelets. Lupus can cause low levels.
  • Complement blood tests: Complements are proteins that help protect against infections and strengthen the immune system. Inflammation due to lupus can cause low complement levels. Common complement tests include C3 and C4 tests.
  • Erythrocyte sedimentation rate (ESR): ESR blood tests check for inflammation. Active lupus may cause high ESR.
  • C-reactive protein (CRP): When there is inflammation, the liver produces CRP. High CRP levels could indicate lupus.

Doctors may recommend blood tests if you have symptoms of lupus. The main symptoms of lupus include:

Doctors can use blood tests to monitor lupus and assess the effectiveness of treatment plans.

For example, effective treatments can help improve anti-dsDNA levels. Monitoring these levels can indicate whether the treatment is working as doctors expect it to.

There is currently no blood test to predict a lupus flare. However, studies are currently looking into the LuGENE blood test. The LuGENE blood test uses artificial intelligence (AI) to look at gene activity. It may be able to predict when a flare-up might happen.

Depending on ongoing research, the LuGENE blood test has the potential to predict lupus flares in the future.

Blood tests alone cannot confirm a lupus diagnosis.

If a doctor suspects lupus, they may recommend other tests, such as:

  • urine tests to check kidney function
  • tissue biopsies, such as kidney and skin biopsies
  • X-rays or other scans of the kidneys, heart, or other organs

While there is no single blood test for diagnosing lupus, one of the main blood tests is the antinuclear antibody (ANA) test. Around 97% of people with lupus have a positive ANA test.

It is possible to have lupus with a negative ANA test. However, this is uncommon.

Blood results with lupus may fluctuate if you are experiencing a lupus flare or if treatment becomes more or less effective.

For example, anti-dsDNA antibodies and complement levels may change if you are experiencing a flare-up of symptoms or if there are any changes to your treatment plan.

Blood tests can help diagnose and monitor lupus. Two of the main blood tests check for antinuclear antibodies (ANAs) and anti-double-stranded DNA (anti-dsDNA) antibodies.

Other antibody blood tests look for histone antibodies, phospholipid antibodies (aPLs), ribonucleoprotein antibodies (anti-RNPs), anti-Smith (anti-Sm) antibodies, and anti-Ro/SSA and anti-La/SSB.

Doctors may also recommend a complete blood count, complement blood tests, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) tests.

Blood tests can help monitor how effective a treatment plan for lupus is. While it is currently not possible to predict when a flare-up of symptoms will happen, the LuGENE blood test has the potential to predict flares in the future.

A doctor may recommend blood tests if you have symptoms of lupus. These include joint and muscle pain, extreme tiredness, and rashes. If you have a lupus diagnosis, your doctor can advise on how frequently they recommend blood tests to monitor the condition.