There are no specific tests that can be used to diagnose fibromyalgia. Instead, doctors look for a variety of diagnostic criteria determined by a physical exam as well as a medical and family history questionnaire. They may also order lab tests and imaging studies to rule out other conditions.
Because fibromyalgia can be so hard to diagnose (since there is no single objective test that can confirm a diagnosis), it takes about five years on average for a person to get an accurate diagnosis.
American College of Rheumatology Diagnostic Criteria
According to the ACR, the diagnostic criteria for fibromyalgia include:
- A score on the Widespread Pain Index and Symptom Severity Scale when (WPI) of ≥7 and a score on the Symptom Severity Scale (SSS) score of ≥5, OR WPI 4–6 and SSS score ≥9
- The presence of generalized pain, defined as pain in at least four of five regions (left upper, right upper, left lower, right lower, low back)
- Symptoms that have been present and consistent for at least three months
The presence of at least 11 out of 18 tender points used to be considered diagnostic of fibromyalgia. But since the ACR updated their diagnostic guidelines in 2010, these tender points are no longer required (although they still can be counted).
A variety of blood tests can help doctors figure out if a person’s symptoms are due to fibromyalgia or something else. Lab work can really diagnose fibromyalgia “by exclusion,” meaning that other disorders are ruled out. These tests may include:
- Tests for hypothyroidism, RA, SLE, or other underlying health conditions
- Tests for inflammation, including C-reactive protein and erythrocyte sedimentation rate (these tests should be negative in people with fibromyalgia but positive in people with RA, for instance)
Currently, research is examining a type of blood test called vibrational spectroscopy, which may help identify specific proteins that can help differentiate fibromyalgia from something else. Although, since this test is still under evaluation, it isn’t available yet for public use.
Like lab work, imaging studies may help doctors diagnose fibromyalgia by “exclusion,” meaning that they can help rule out other conditions. For example, joint damage due to arthritis can show up on an X-ray, but X-rays won’t show fibromyalgia.
In a research setting, scientists have used magnetic resonance spectroscopy to examine biochemical changes in the nervous system. They have observed that people with fibromyalgia have higher concentrations of a certain type of neurotransmitter in certain pain-related regions of the brain. But doctors aren’t currently able to use this technology to help them diagnose fibromyalgia in a clinical setting.
Who can diagnose fibromyalgia?
Only a licensed and board-certified medical doctor can diagnose fibromyalgia, such as a family physician, internist, or rheumatologist.
What can be mistaken for fibromyalgia?
Many conditions can present like fibromyalgia, and these are generally the conditions that a doctor must rule out first before confirming a diagnosis of fibromyalgia. These conditions include:
- polymyalgia rheumatica,
- myofascial pain syndrome, and
- chronic fatigue syndrome.