How to Diagnose Fibromyalgia

4 minutes

Since there isn't yet a specific study that helps detect fibromyalgia, the diagnosis is made based on the symptoms. For this reason, the interview with the patient is key.

Written by Maite Córdova Vena

Last update: 16 December, 2022

As with many other diseases, talking to the patient and a physical examination are essential in order to diagnose fibromyalgia. The doctor must take into account the symptoms that the patient mentions to them during the appointment.

In general, the symptoms are a combination of generalized pain and fatigue with somatic and cognitive symptoms. This combination is what constitutes the clinical criteria of the American College of Rheumatology. Before commenting on them, we must first consider part of their history.

How to diagnose fibromyalgia

Diagnosing fibromyalgia can be difficult. — The diagnosis of fibromyalgia is primarily clinical, and is implied by the diagnostic criteria used by physicians.

The diagnostic criteria approved in 1990 were based mainly on the presence of generalized pain (for more than 3 months) and tenderness to palpation in any of the 18 tender points that are located in the body.

However, over time it was necessary to update the criteria, given the difficulties they posed for physicians when making the evaluation, as stated in the MSD Manual.

In 2011, the new diagnostic criteria were approved, and according to the Madrid Fibromyalgia Association (AFIBROM) these now include:

Pain during the last 2 weeks
Symptom severity (tiredness, unrefreshing sleep, cognitive symptoms, and others) for at least 3 months.
There is no underlying cause (other diseases) to explain the pain and the rest of the above symptoms.

However, the change in criteria doesn’t mean that sensitive points are no longer taken into account. On the contrary, what was done was to update the body map of painful areas in order to continue taking into account hypersensitivity, which is also quite common in patients.

Hypersensitivity to touch is still being systematically evaluated.

Differential diagnosis

The diagnosis of fibromyalgia implies ruling out more frequent pathologies — Some neurological and rheumatological diseases can be confused with fibromyalgia, which is why they are taken into account as differential diagnoses.

Fibromyalgia is suspected when the patient reports asthenia as the predominant symptom (a fatigue that isn’t relieved with rest), and generalized pain (which is disproportionate to the stimuli and physical findings), despite laboratory tests with normal results.

But, in order to avoid reaching hasty conclusions, the doctor must first rule out other diseases that may have similar symptoms. The most prominent would be the following:

Myositis
Osteoarthritis
Polymyalgia
Sleep apnea
Rheumatoid arthritis
Lyme’s disease
Addison’s disease
Chronic Fatigue Syndrome
Systemic lupus erythematosus
Guillain-Barré syndrome
Post-traumatic stress disorder

To be able to rule these out, the doctor will have to ask the patient for several tests. According to the MSD Manual, these can include complete blood tests, and also:

Erythrocyte sedimentation rate (ERS) or C-reactive protein
Creatine kinase (CK)
Studies for hypothyroidism and hepatitis C (which can cause asthenia and generalized myalgias).
Serological tests for rheumatic disorders.

The functional magnetic resonance imaging of the brain isn’t a diagnostic test for fibromyalgia, but in some rare cases, it may be requested to confirm/rule out suspicions.

There’s no single test to diagnose fibromyalgia. However, research is ongoing in this regard.

Generalized pain index to diagnose fibromyalgia

The Generalized Pain Index (Widespread Pain Index [WPI]) is based on a body map that includes 19 points in which the patient experiences pain for at least one week prior to the consultation:

For each area that is identified as painful, 1 point is counted.
The total number of areas can range from 0-19.

Symptom severity scale

The Symptom Severity Score [SS-Score] allows the degree of severity of symptoms to be measured from 0-3. These fall into 3 categories: fatigue, cognitive symptoms, and non-restorative sleep.

Apart from the results of the index and scale, other somatic symptoms are taken into account, such as the fact that there’s no underlying cause to explain them and the persistence of all complaints for at least 3 months.

Confirming the diagnosis

Fibromyalgia is a disease that continues to be a challenge for the medical community given its uncertain origin, the difficulties involved in diagnosis (mainly due to the wide heterogeneity of the clinical symptoms) and other aspects.

There are various positions regarding fibromyalgia. Therefore, not all specialists approach it in the same way, and not all give the same importance to certain parameters. For this reason, the approved diagnostic criteria are often a frame of reference. In addition, these aren’t fixed, but are subject to regular updates.

Even though this disease isn’t a form of arthritis (because it doesn’t cause inflammation or joint damage), due to the pain it causes and other symptoms, consultation with the rheumatologist is valuable.

If you have already visited your family doctor and they have referred you to another specialist (such as a rheumatologist or neurologist) to evaluate your situation more thoroughly, don’t forget to go for the consultation. This will help you to specify what is happening , as well as to receive the appropriate help.

Finally, you should keep in mind that it isn’t uncommon for people who suspect that they suffer from fibromyalgia to request a second opinion.