How Is Fibromyalgia Diagnosed?

Fibromyalgia is a complex and often misunderstood condition that affects millions of people worldwide. Many patients considering their symptoms may be wondering: How is fibromyalgia diagnosed? And who can tell me more about whether I have it?

Despite its prevalence, diagnosing fibromyalgia remains a challenge, partly due to the overlap of its symptoms with other conditions, the lack of a lab-based test, and a lack of doctors who treat the condition.

In this article, we will dive into the current diagnostic criteria for fibromyalgia, how clinicians approach diagnosis in practice, and how to start the journey to getting answers about your own symptoms and their treatment.

Current Diagnostic Criteria for Fibromyalgia

Unlike many medical conditions, fibromyalgia does not have a specific biomarker or laboratory test for confirmation. Instead, healthcare providers use established diagnostic criteria to assess whether a patient’s symptoms align with the hallmarks of the condition.

The American College of Rheumatology (ACR) updated its diagnostic criteria for fibromyalgia in 2010 and again in 2016. The diagnosis of fibromyalgia today is based on a combination of clinical evaluation, patient history, and the exclusion of other potential causes for the symptoms. 

The diagnostic criteria now include the following key components:

1. Widespread Pain Index (WPI): This is a measure of the areas of the body where a patient has experienced pain over the past week. For a diagnosis of fibromyalgia, patients must report pain in at least 4 of the 5 regions of the body (neck, upper back, lower back, left side, and right side) chronically (e.g. for at least three months).
   
2. Symptom Severity Scale (SSS): This scale assesses the severity of other common fibromyalgia symptoms such as fatigue, sleep disturbances, and cognitive difficulties. The SSS is rated from 0 to 12 based on the intensity of these symptoms. To meet the diagnostic criteria, a patient’s symptom severity scores 9 or higher on the SSS.
   
3. Duration of Symptoms and Exclusion of Other Conditions: Symptoms must be present for at least three months and cannot be attributed to other underlying conditions.

These criteria allow for a more standardized diagnosis, focusing on patient-reported pain levels and symptom severity. Importantly, this new approach has removed the previous emphasis on the presence of “tender points,” which were once a key part of the diagnostic criteria.

This revised criteria also highlights that fibromyalgia can exist on a spectrum, with a total score that indicates a level of symptom activity or “fibromyalgianess.” Whereas past criteria have focused on a more “all-or-nothing” approach to diagnosis, clinicians who are familiar with the condition recognize that a patient may have fibromyalgia with more mild or more severe symptoms, depending on the responses to the WPI and SSS. 

The Tender Point Theory and Past Diagnostic Criteria

Before the 2010 updates, the American College of Rheumatology used a set of diagnostic criteria that included the presence of specific “tender points” on the body. These tender points were areas of the body where the patient would feel pain when pressure was applied. There were 18 designated tender points, located at specific sites such as the back of the head, shoulders, knees, and elbows. To be diagnosed with fibromyalgia, patients needed to experience pain in at least 11 of these 18 points.

This approach, established in 1990, was widely used but had limitations. One of the main criticisms was that it was too focused on a physical exam that required the identification of localized tender points, a feature not necessarily present in all patients with fibromyalgia. Furthermore, it did not adequately account for the other symptoms of fibromyalgia, such as cognitive difficulties, fatigue, and sleep disturbances.

The limitations of the 1990 criteria led to the 2010 revision, which placed less emphasis on tender points and instead focused on broader, more subjective symptoms. The shift to the WPI and SSS allowed for a more comprehensive understanding of fibromyalgia and addressed concerns that the old criteria were too narrow.

Clinical Tests Used in Fibromyalgia Diagnosis

Because fibromyalgia shares symptoms with many other chronic pain conditions, it is important for healthcare providers to rule out other potential causes for the pain and discomfort. The diagnostic process often involves several tests and evaluations to ensure that other conditions are not responsible for the patient’s symptoms.

Patients often see rheumatologists for this testing, because many of the tests are used to assess for inflammatory or autoimmune conditions that are routinely treated in rheumatology, like rheumatoid arthritis, lupus, or hypothyroidism. 

Some of the key tests and evaluations used to rule out other conditions include:

1. Antinuclear antibody (ANA) and C-reactive protein (CRP): These tests measure inflammation levels in the body, and abnormal levels may suggest autoimmune or inflammatory diseases instead (or in addition to) fibromyalgia.
2. Thyroid function tests: Tests like TSH, T4 and thyroid antibody tests measure thyroid function. Hypothyroidism, or underactive thyroid, can cause fatigue, muscle pain, and other symptoms similar to fibromyalgia.
3. Vitamin D levels: Low vitamin D is associated with musculoskeletal pain and may contribute to fibromyalgia-like symptoms.
4. Imaging Studies: While fibromyalgia is not diagnosed based on imaging, X-rays, MRIs, and CT scans may be used to rule out other conditions such as osteoarthritis or disc herniations in the spine, which could cause similar symptoms.
5. Sleep Studies: Many patients with fibromyalgia experience sleep disturbances, and sleep disorders such as sleep apnea or restless leg syndrome can exacerbate fibromyalgia symptoms. A sleep study may be ordered to diagnose sleep-related issues that could contribute to the patient’s overall symptoms.
6. Other Specialized Tests: In some cases, rheumatologists may use muscle biopsy (though rarely) or nerve conduction studies to rule out conditions like neuropathy or myositis (muscle inflammation).

By performing these tests, healthcare providers aim to identify or exclude other conditions that might explain the symptoms, helping to narrow down the diagnosis to fibromyalgia. Fibromyalgia may also exist alongside these conditions, leading clinicians to discuss fibromyalgia with patients in the context of other conditions they may be experiencing. 

How Fibromyalgia Differs from Other Diagnoses 

Fibromyalgia presents with several distinct patterns that help differentiate it from other chronic pain conditions. These patterns include:

1. Widespread Pain vs Localized Pain: The hallmark of fibromyalgia is widespread pain that occurs on both sides of the body and above and below the waist. This widespread pain is different from other conditions, such as osteoarthritis or rheumatoid arthritis, where pain is usually localized to specific joints, or like chronic lower back pain.¹ It is also different from myofascial pain syndrome, where localized points are more prominent.
   
2. Non-Inflammatory vs Inflammatory Markers: Unlike conditions such as rheumatoid arthritis, blood tests for inflammatory markers like CRP are often normal in fibromyalgia, which helps differentiate it from autoimmune conditions that show elevated markers of inflammation. However, new research suggests that there may be a link in elevated CRP and higher symptom activity in fibromyalgia patients, and more research is needed.²
   
3. Chronic Fatigue vs Pain Alone: One of the most common symptoms reported by individuals with fibromyalgia is profound fatigue, often accompanied by poor sleep quality or unrefreshing sleep. This is a key distinguishing factor from other chronic pain conditions, where fatigue may not be as prominent.
   
4. Cognitive Symptoms vs Bodily Symptoms: Often referred to as fibro fog, cognitive difficulties such as memory problems, poor concentration, and mental fogginess are distinctive features of fibromyalgia. These symptoms are not commonly seen in other chronic pain conditions like osteoarthritis or peripheral neuropathy.
   
5. Response to the “Thumbnail Test”: Patients with fibromyalgia often report heightened sensitivity to pressure and pain in response to stimuli that would not typically be painful for others: for example, putting your thumbnail pressure into your skin until the nail turns white.³ This heightened sensitivity is a hallmark of central sensitization, a mechanism thought to underlie fibromyalgia. 

What Type of Doctors Commonly Diagnose Fibromyalgia?

Fibromyalgia is typically diagnosed by a rheumatologist, a physician specializing in musculoskeletal diseases and autoimmune conditions. Rheumatologists are trained to identify conditions that involve chronic pain, inflammation, and immune dysfunction, making them well-suited to diagnosing fibromyalgia and ruling out other conditions.

However, diagnosing fibromyalgia often involves a multidisciplinary approach, and some rheumatologists don’t treat fibromyalgia long-term after a diagnosis has been established. Finding a fibromyalgia specialist for routine treatment may be beneficial. Treatment for fibromyalgia typically involves a combination of medications, physical therapy, lifestyle medicine, and alternative therapies. 

Summary

Fibromyalgia remains a challenging condition to diagnose due to its complex and often overlapping symptoms with other chronic pain conditions. The current diagnostic criteria, focusing on widespread pain and symptom severity, have helped provide a clearer path to diagnosis, though the condition still requires the careful exclusion of other potential causes through blood tests, imaging, and clinical evaluation. 

While rheumatologists are typically responsible for diagnosing fibromyalgia, a multidisciplinary team of healthcare providers is often involved in its treatment. For patients with fibromyalgia, early diagnosis and a comprehensive treatment plan are key to improving quality of life and managing symptoms effectively.

Sources

¹ Viniol A, Jegan N, Leonhardt C, Brugger M, Strauch K, Barth J, Baum E, Becker A. Differences between patients with chronic widespread pain and local chronic low back pain in primary care–a comparative cross-sectional analysis. BMC Musculoskelet Disord. 2013 Dec 13;14:351. doi: 10.1186/1471-2474-14-351. PMID: 24330525; PMCID: PMC3878755.

² Beiner E, Brenner Miguel S, Friederich HC, Tesarz J; PerPAIN Consortium. Elevated high sensitive C-reactive protein in fibromyalgia. Front Psychiatry. 2023 Nov 30;14:1237518. doi: 10.3389/fpsyt.2023.1237518. PMID: 38098640; PMCID: PMC10720424.

³ Schoen CJ, Ablin JN, Ichesco E, Bhavsar RJ, Kochlefl L, Harris RE, Clauw DJ, Gracely RH, Harte SE. A novel paradigm to evaluate conditioned pain modulation in fibromyalgia. J Pain Res. 2016 Sep 26;9:711-719. doi: 10.2147/JPR.S115193. PMID: 27713648; PMCID: PMC5045220.