What are the approach considerations in the workup of fibromyalgia?

Updated: Apr 23, 2020
  • Author: Chad S Boomershine, MD, PhD, CPI, CPT; Chief Editor: Herbert S Diamond, MD  more...
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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 B-12 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.

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