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Fibromyalgia: A diagnosis of exclusion?


You don’t understand: I hurt somewhere in my body all the time. I have trouble sleeping because of it. I can’t exercise because I have no energy. My friends avoid me because they know I won’t go out with them. My family accommodates me, but I feel bad making them adjust everything. The pain has taken over my life, while everyone else I know is actually living life.

I see patients in this frustrating and life-sapping situation routinely. They may be 25, they may be 65 — but what they all want to know is “Why?”

This is often a challenging medical question to answer. Fibromyalgia is one of the most well-known diagnoses of widespread chronic pain. Fibromyalgia is characterized as migrating joint and muscle pain that’s related to the central nervous system, without any observable cause of that pain, such as inflammation. It’s estimated that 2% to 8% of the world’s population is affected by fibromyalgia, with 2 to 3 females affected for every male. Fibromyalgia is most common between ages 25 and 60.

There is currently no diagnostic study or blood test that definitively proves a person has fibromyalgia, though research is underway to find such a test. That’s one reason why fibromyalgia remains a challenging diagnosis to make for many health care providers — with misinformation and the stigma that has been attached to the disorder being additional reasons.


What to rule out

A description of your symptoms and a physical exam testing for pain sensitivity at certain points on the body are ways health care providers can help make a fibromyalgia diagnosis. Still, the syndrome is also often considered a “diagnosis of exclusion.” This means that part of the diagnostic process is ruling out other potential causes of symptoms.

What could this include? This list is long, but can include conditions such as systemic lupus erythematosus, rheumatoid arthritis, spondyloarthritis, osteoarthritis, polymyalgia rheumatica, a side effect of drug therapy such as statin therapy and gluten intolerance. Other conditions to consider include spinal cord compression, Sjögren’s syndrome, thyroid disorders, adrenal dysfunction and vitamin D deficiency.

A blood test and imaging studies can raise suspicion of — or rule out — most of these conditions, though working with your health care provider to determine appropriate testing is important.

At Mayo Clinic, the laboratory tests and diagnostic studies listed below are typically performed prior to a patient being evaluated at our Fibromyalgia and Chronic Fatigue Clinic. Blood tests often include:

  • A complete blood count (CBC) with differential, the basic breakdown of types of white blood cells seen on the sample. This screens for anemia, infections, blood cancers or immune system concerns.
  • A basic metabolic panel (BMP). This looks for imbalances, such as high or low chemistry levels (e.g., sodium, potassium, calcium).
  • A connective tissue disease panel that screens for diseases such as lupus, rheumatoid arthritis, CREST syndrome, scleroderma, mixed connective tissue disease and polymyositis.
  • A celiac disease panel to look for signs of gluten intolerance.

Other blood tests look to measure:

  • Cortisol (early morning), which helps assess adrenal function
  • Dehydroepiandrosterone (DHEA) to assess adrenal function and certain problems related to female hormones
  • Ferritin for determining iron stores and as a marker for inflammation
  • Vitamin D levels, which can be in deficiency or excess
  • Serum protein electrophoresis (SPEP), which measures specific protein levels
  • Sedimentation rate and C-reactive protein (CRP), which are markers of inflammation
  • Creatine kinase (CK) to indicate muscle injury

Additional tests may include:

  • Overnight oximetry to screen for sleep-disordered breathing such as obstructive sleep apnea.
  • X-rays and other imaging tests, depending on the pain location


These tests and studies often don’t directly diagnose a condition, but they may direct your health care team to consider additional diagnostic studies based on their results. For example, if a person has findings in the tests that raise suspicion of a connective tissue disease, a specialist such as a rheumatologist may be consulted.

Keep in mind that findings of a potential additional diagnosis based on testing doesn’t mean you don’t have fibromyalgia. For example, you may have a diagnosis of lupus and are properly treated for the condition to the extent you have no evidence of active disease. If you continue to have symptoms that match those of fibromyalgia, however, it’s reasonable to still consider a fibromyalgia diagnosis.

Fibromyalgia remains a challenging diagnosis to make by many health care providers in spite of so much more being known about the condition compared to years past. While more research is underway and necessary, health care providers now have a diagnostic path to pursue so that diagnosis is made in a timely manner and treatment can be instituted sooner rather than later, which has been shown to improve outcomes and quality of life.

Lasonya T. Natividad, APRN, C.N.P., M.S.N

Lasonya Natividad is a nurse practitioner currently working in the Department of General Internal Medicine where part of her time is spent working with the Fibromyalgia and Chronic Fatigue Clinic. She has been on staff at Mayo Clinic for a total of 19 years. She is heavily involved in the Rochester arts community with music and theater.

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