Marker Could Separate Fibromyalgia from Two Types of Arthritis

Is This Our Long-Sought Diagnostic Marker?

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Analysis of a particular type of immune-system cell may provide diagnostic markers differentiating three common and often overlapping pain conditions: fibromyalgia (FMS), rheumatoid arthritis (RA), and spondyloarthritis (SpA). (RA and SpA are both forms of autoimmune arthritis.)

Researchers compared mucosal-associated invariant T cells, also called MAIT cells, from people with these three illnesses along with healthy donors.

They say FMS, RA, and SpA all were linked to decreased MAIT cells. Additionally, they found several markers that appeared to differentiate each of the three conditions from healthy people:

  • Seven markers that appeared to differentiate FMS, including three chemokine receptors and a natural killer receptor;
  • Two markers that appeared to differentiate RA;
  • And one marker that appeared to differentiate SpA.

Researchers say that these MAIT-cell markers could, along with current diagnostic procedures, provide a more objective standard for diagnosing FMS, RA, and SpA.

Telling These Pain Conditions Apart

Doctors and patients would all benefit from better diagnostic criteria when it comes to these similar pain conditions. Doctors could be more confident in their conclusions and may be more willing to diagnose these disorders — which could speed up the diagnostic process and get patients matched up with treatments sooner.

Those of us with FMS generally know all too well what it means to have a condition that lacks objective diagnostic criteria. The authors of this study said it well:

"While many rheumatologists and pain physicians have considered it to be a pain disorder, psychiatry, psychology, and general medicine have deemed it to be a syndrome (FMS) or psychosomatic disorder. The lack of concrete structural and/or pathological evidence has made patients suffer prejudice that FMS is a medically unexplained symptom, implying inauthenticity." –Sugimoto, et al.

Objective diagnostic markers become even more important when you have more than one of these conditions, which many of us do (including me). They each require different treatments, so if only one is diagnosed, you're likely to have a high symptom load. Sometimes, it's difficult to get a doctor to pay attention when you bring up new pains because they attribute it to your previously diagnosed condition.

When it comes to the people in your life, a blood test showing an abnormality can go a long way toward getting them to accept your illness and the disability that may come with it. It would also likely help in legal matters as well as getting reasonable accommodation at work.

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Sugimoto C, et al. PLoS One. 2015 Apr 8;10(4):e0121124. Mucosal-associated invariant T cell is a potential marker to distinguish fibromyalgia syndrome from arthritis.

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