Diagnosis and Tests

Blood Tests for Diagnosing and Measuring Lupus

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Blood tests are a critical part of detecting and measuring lupus. Even though currently available blood tests don’t offer certainty, new biomarker-based options may provide deeper insights.

When you get a blood test, a small sample of blood is taken from a vein or the finger and then analyzed. You may be asked to squeeze your hand or put a band or ribbon on your arm. This helps the clinician extract blood more easily. Otherwise, you also do not need to get ready for the blood tests listed below. There is no fasting or other preparations involved. Here is some information for if you are required to fast prior to the test.

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Can you diagnose lupus with blood tests alone?

Today, you cannot diagnose lupus with a single blood test. Even antinuclear antibody tests are not definitive. They are just part of the puzzle. The current lupus diagnostic workup includes:

  • several different blood tests
  • tests of kidney and liver function
  • symptom records
  • a review of your family history
  • a review of your medical history

You can read more about getting diagnosed on the CDC’s webpage.

 

Behind the scenes: blood tests

After trained professionals take your blood, it is sent off to a lab for testing. The blood samples are kept track of throughout the process with barcodes. These barcodes don’t usually tell the lab technicians much about you, but they do make sure that you receive the correct test results when they are all done. 

For many tests, the blood is first spun very fast in a machine called a centrifuge. The centrifuge forces the blood to separate into two different parts: the plasma (the liquid portion of the blood) and the serum (the solids that are in the blood). Blood tests can use plasma, serum, or whole blood, depending on the tests.   

These days, tests are usually done by a machine which does the analysis under the supervision of a lab technician. The machine can do various things, including acting as a microscope or performing chemical experiments on the blood sample. Exactly what the machine is tasked to do depends on the specifics of the test.

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Commonly used lupus blood tests

Complete Blood Count (CBC)

A complete blood count looks at whole, unseparated blood. The goal of this test is to look at the overall health of the various cells that make up blood, including platelets, white blood cells, and red blood cells. Of particular importance to lupus are the white blood cells, which are a part of the immune response. If white blood cell levels are high, that can mean that there are abnormally high levels of inflammation in the body.

While lupus is not always the cause, a complete blood count test can find signs of immune system distress, potential blood clotting issues, and anemia. These factors can have major impacts on the health of Lupus Warriors.

 

Clotting Test

Blood samples may be tested to see if they clot properly. If they aren’t, this can indicate that there is a problem with the platelets. This can be a sign of lupus, and can also be life-threatening if not investigated and treated.

 

Antinuclear Antibody Test (ANA)

The ANA test (AntiNuclear Antibody) looks for specific antibodies that are the usual culprits in autoimmune disease. Many of these antibodies attack the nucleus of cells, where the DNA is located. 

Although a positive reading for ANA doesn’t mean that a person has lupus, ~97% of people with SLE have positive ANA tests. Still, a positive ANA is part of the clinician diagnosis checklist.

 

Other Autoantibody Tests

But, ANAs are not the only antibodies in the blood. Other antibodies can help clinicians understand problems because they are associated with particular conditions. For example:

  • Anti dsDNA is associated with systemic lupus erythematosus (SLE) and can be used to gauge severity in people with lupus nephritis
  • Anti-ro/SSA and Anti-La/SSB antibodies are associated with SLE and Sjogren’s syndrome
  • Anti-histone antibodies are associated with both drug-induced lupus and SLE

Because these antibodies are associated with other conditions, they are usually used to confirm a diagnosis, not make one.

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C3 and C4 Reactive Protein Test

This blood test measures proteins called “complement” proteins in your blood. These proteins are masters at teamwork – they are called complement proteins because they assist each other in tracking down, marking, and killing disease-causing organisms like bacteria. Some act like triggers for others, causing a chain reaction that protect the body. This is known as an immune system cascade.

However, in autoimmune diseases such as lupus, the whole system is turned on its head and some of these complement proteins might be tracking down, marking, and killing a person’s own cells. 

This is usually tested by causing a chemical chain reaction in the sample that mimics an immune response. The analyzing machine then measures how much of the complement proteins were consumed. There are many different complement proteins, labeled from C1 to C9, but the ones most commonly measured are C3 and C4. These are particularly low in people with lupus, so this test can be used to confirm lupus in at-risk people. 

 

Erythrocyte Sedimentation Rate

This test measures the speed and amount of red blood cells (erythrocytes) that naturally settle to the bottom of the test tube without being centrifuged. If a lot of blood cells settle at the bottom over a short period of time, then it can hint at many body issues such as infections, cancer, and lupus.

 

New Technology: Biomarker Tests

Advances in predictive modeling and laboratory equipment are helping unlock new testing strategies. Researchers and companies are working on improving the accuracy of blood tests with the help of biomarkers. For example, Progentec is developing 3 new lupus blood biomarker tests:

  • a flare prediction tool
  • lupus disease activity level
  • a lupus diagnosis tool

These new tests provide Lupus Warriors and their treatment teams with actionable insights into lupus. Are treatments working? Is it really lupus? Progentec is working to help provide answers to those questions and more which can radically improve the management of lupus.

[Editor’s note: Progentec owns LupusCorner]

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Should I get blood tests?

In general, yes. Get blood tests done for lupus as recommended by your doctor. 

If you are worried about side effects, only a few test tubes of blood are taken so it is rarely harmful. You may feel pain or soreness at the site. But, other side effects such as swelling, bleeding, fainting, and infection are very rare.

There are many methods to help distract you from the needle stick if that bothers you. There are even special devices that use cold and vibration to cancel out the pain of the needle. Though you should always make sure that you can handle the vibration and temperature change before using it.

Blood tests are low-risk and don’t take much time. They can help confirm a diagnosis and help you better understand your unique lupus symptoms. In the end, this enables you to create a treatment plan that is right for you. 

Comments (4)

4 thoughts on “Blood Tests for Diagnosing and Measuring Lupus

  1. I had all the tests my md wanted me to have. Only the ANA was off. Why don’t they look at the whole patient, their symptoms, and actually take time to look, and talk about symptomolgy with the patient. I was told it would be 8 months to see a Rheumatologist. Also, I was told to move to a dryer climate like Arizona. What is wrong with our MD’s? Any suggestions will be great!!

    1. I have waited months to see specialists as well and after only 10 minutes of trying to descibe my symptom history they cut me off and want to run bloodwork that, until recently, all came back normal. This, they concluded nothing was wrong in spite of my 50 different symptoms involve every system of my body. It is totally ridiculous! After 20+ years of being sick and finding no answers, my bloodwork is FINALLY displaying abnormalities and the doctors are FINALLY paying attention and trying to help me. But I had to get to the point were I’m half-dead for this to happen.

    1. Hi Deanna,
      These tests are primarily used to provide a more accurate picture into the current level of disease activity with lupus. By doing so, they will help your clinicians better measure the success of treatments and develop better plans.
      Thank you for writing in and being part of the LupusCorner community — If there are other topics that would be helpful for us to cover, please let me know
      -Brett

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