Blood Tests for Diagnosing Back Pain

Blood tube sitting on blood results with technician at microscope in lab

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Blood tests are generally not used for diagnosing the cause of back pain, but in some cases, they are—particularly if your doctor suspects an infection or inflammatory arthritis.

When trying to find the reason for your back pain, your doctor will likely take a medical history, do a physical exam, and possibly order some diagnostic tests. While some feel an over-reliance on diagnostic tests exists in our society; such tests generally do not in and of themselves definitely diagnose spine pain. For example, the National Institute of Arthritis and Musculoskeletal and Skin Diseases (which is part of the National Institutes for Health or NIH) says that MRIs can reveal abnormalities in the spine but you may not feel pain or experience other symptoms at all. The National Institute of Arthritis and Musculoskeletal and Skin Diseases also says that healthy, pain-free people can have elevated sed levels.

Common Tests

Below is a list of the most common blood tests used for back pain.

  • Complete blood count (CBC) may point to infections or inflammation.
  • SED Rate, or erythrocyte sedimentation rate is a measure of inflammation that may suggest infection. If your SED Rate indicates that inflammation is present, the possibilities for an underlying cause may be some forms of arthritis or more rarely, a tumor.
  • CRP or C-reactive protein is another blood test that is used to measure inflammation that may indicate an infection or some forms of arthritis.
  • HLA-B27 is a genetic marker in the blood that is more common in people with ankylosing spondylitis and reactive arthritis. A test for this marker may be done if your doctor suspects either disease. Ankylosing spondylitis is one type of inflammatory arthritis that usually first affects the sacroiliac joints and hips, and later the spine. Reactive arthritis is a type of arthritis that occurs after an infection in a different body system or area.
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Article Sources

  • Back Pain. National Institute of Arthritis and Musculoskeletal and Skin Diseases. NIH website. Updated August 20, 2018.