Fibromyalgia Workup

Updated: Jul 26, 2023
  • Author: Chad S Boomershine, MD, PhD, CPI, CPT; Chief Editor: Herbert S Diamond, MD  more...
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Approach Considerations

Patients with fibromyalgia do not have characteristic or consistent abnormalities on laboratory testing. However, routine laboratory and imaging studies are important to help rule out diseases with similar manifestations and to assist in diagnosis of certain inflammatory diseases that frequently coexist with fibromyalgia. In addition to complete blood cell (CBC) count and differential count, basic metabolic panel, and urinalysis, the following limited evaluation is reasonable.

  • Thyroid-stimulating hormone: Hypothyroidism shares many clinical features with fibromyalgia, especially diffuse muscle pain and fatigue.

  • 25-Hydroxy vitamin D level: Low levels can cause muscle pain and tenderness.

  • Vitamin B12 level: Very low levels can cause pain and fatigue.

  • Iron studies, including serum iron, total iron-binding capacity, percent saturation, and serum ferritin: Iron deficiency is very common in fibromyalgia patients and can cause or worsen fatigue, poor sleep, and depressive symptoms.For patients with restless legs syndrome, percent saturation should be maintained above 20% and serum ferritin should be kept above 50 ng/mL.

  • Magnesium: Low levels can lead to muscle spasms, which are common in fibromyalgia patients; magnesium supplementation can also improve symptoms in some fibromyalgia patients; recommended magnesium levels in fibromyalgia patients are at least 2 mEq/L.

The erythrocyte sedimentation rate (ESR) is often recommended as a routine laboratory test in fibromyalgia patients to rule out the presence of inflammatory disorders that may mimic symptoms. The upper limit of normal for the ESR in women is half their age (eg, a level of 40 in an 80-year-old women is normal), and in men is half their age minus 10.

While the ESR is usually normal in patients with fibromyalgia, it is a nonspecific measure of inflammation and mild elevations may not be meaningful. For example, the ESR can be mildly elevated in obese patients. However, a high ESR may be indicative of an inflammatory disorder or occult malignancy that should be thoroughly evaluated.

Routine antinuclear antibody (ANA) or rheumatoid factor (RF) testing in not recommended unless patients have signs or symptoms concerning for systemic lupus erythematosus (SLE) or rheumatoid arthritis. A low-titer positive ANA or RF level is common in the general population, so these findings may be of no clinical significance in a fibromyalgia patient.

Formal sleep studies may be useful in patients whose sleep does not improve with the usual conservative measures (eg, elimination of caffeine, prescription of hypnotics or nighttime tricyclics). These studies can be performed as part of a formal assessment by a neurologist or pulmonologist experienced in sleep disorders.

Serum transferrin saturation and serum ferritin screening can be useful for detecting the unusual cases of hemochromatosis in which patients present with diffuse arthralgias and myalgias. Consider screening with a serum transferrin saturation and a serum ferritin concentration in patients aged 40-60 years, especially those with small-joint arthropathy in the hands and/or calcium pyrophosphate dihydrate deposition disease (CPPD).

The antipolymer antibody assay is a blood test. Antipolymer antibodies are present in approximately 50% of patients with fibromyalgia. This biologic marker may provide conclusive evidence for a subgroup of people with fibromyalgia.

There are no histologic abnormalities seen in fibromyalgia syndrome. Earlier belief that fibromyalgia was associated with inflammation in muscle fascia has been disproved.

Carefully assess all possible causal or perpetuating factors. Investigate psychological and sociocultural factors and identify any specific regional sources of ongoing nociceptive pain (eg, degenerative spondylosis, bursitis).


Self-Report Forms

While waiting to see the physician, the patient, in a few minutes, can complete a simple self-report form [103] that incorporates visual analogue scales for pain and fatigue and a global self-assessment of overall status, along with validated scales for physical and psychological health status such as the following:

  • Modified Health Assessment Questionnaire
  • Fibromyalgia Impact Questionnaire
  • Checklist of current symptoms
  • Scales for helplessness and cognitive performance
  • The Physician Health Questionnaire–9 for depression
  • The Generalized Anxiety Disorder–7 questionnaire for anxiety
  • The Mood Disorder Questionnaire to screen for bipolar disease

Easily adaptable to a busy practice, the use of self-report forms provides information that is invaluable for the psychosocial assessment of pain, both for aiding with diagnosis and monitoring response to therapy.


Psychometric Testing

Psychometric testing includes the following:

  • Minnesota Multiphasic Personality Inventory
  • Social Support Questionnaire
  • Sickness Impact Profile
  • Multidimensional Pain Inventory (MPI)

In multidisciplinary settings, information obtained from these tests is useful for a more comprehensive assessment. For example, subgroups of patients with chronic pain can be identified based on MPI responses that appear to predict response to interdisciplinary therapeutic interventions.