Fibromyalgia is usually diagnosed by documenting the patient's medical history, ruling out disorders and diseases that may be mimicking or exacerbating fibromyalgia, and by utilizing the criteria last updated by the American College of Rheumatology (ACR) in 2010.
The ACR criteria evaluate pain location and severity but are less focused on specific tender points. They also take into account a person's symptoms — how the person feels. A person would be considered to have fibromyalgia if that person met the following:
- Has had pain and symptoms over the past week, based on the total of the following:
- Number of painful areas out of 19 parts of the body
- Plus the level of severity of these symptoms:
- Waking unrefreshed
- Cognitive (memory or thought) problems
- Plus the number of other general physical symptoms
- Symptoms have been present at a similar severity level for at least 3 months.
- The person does not have another disorder that would explain the pain.
Laboratory tests can be useful to help diagnose conditions with symptoms similar to fibromyalgia, such as rheumatoid arthritis, Sjögren syndrome, thyroid disease, and lupus. It is not usually cost effective or necessary to do extensive screening. General tests that may be ordered include:
- CMP (comprehensive metabolic panel) – to examine electrolytes, proteins, liver and kidney function, calcium, and glucose
- CBC (complete blood count) – to look for anemia, a possible cause of weakness and fatigue
- TSH (thyroid stimulating hormone) and/or other thyroid testing since hypothyroidism can cause symptoms similar to fibromyalgia
- ANA (anti-nuclear antibody) - to rule out autoimmune disorders, such as lupus or Sjogren syndrome
- CK (creatine kinase) - to rule out other conditions that can cause muscle weakness or pain
A healthcare practitioner will typically consider the following in developing a diagnosis: results of the general tests, the patient's history (including family history and risk factors for certain diseases), and results of the physical examination. Based on these findings, some additional tests could be done.
Meanwhile, researchers continue to look for new testing protocols that may be more specific for fibromyalgia.
Electromyography (EMG) may be performed to assess the health of muscles and the nerves that control them. For more on this procedure, read the Electromyography article on the Mayo Clinic web site. Occasionally, an imaging scan such as an MRI (magnetic resonance imaging) may be ordered to help rule out the possibility of multiple sclerosis or other diseases that may cause symptoms similar to fibromyalgia.