Association of Vitamin B12, Vitamin D, and Thyroid-Stimulating Hormone With Fatigue and Neurologic Symptoms in Patients With Fibromyalgia

OBJECTIVE: To assess the association between vitamin B12 (B12) deficiency and the prevalence of fatigue and prespecified neurologic symptoms in patients with fibromyalgia. PATIENTS AND METHODS: A retrospective chart analysis of patients diagnosed with fibromyalgia in the years 2015-2020 was performed. The values of B12 were collected. The chart reviews assessed reported fatigue and neurologic symptoms, including brain fog, memory loss, cognitive impairment, paresthesias, numbness, and tingling, to assess their correlation with B12 levels. Concurrent vitamin D and thyroid-stimulating hormone levels were reviewed to assess their association with fibromyalgia. RESULTS: A total of 2142 patients with fibromyalgia with documented levels of B12 and vitamin D were included. Of them, 42.4% had B12 deficiency (<400 ng/L). Fatigue and memory loss were more common in the B12 deficiency group. After adjusting for vitamin D levels, B12 deficiency remained statistically significantly associated with the presence of fatigue (odds ratio, 1.39; 95% confidence interval, 1.11-1.75; P=.004). CONCLUSION: This is the first study to report the association of B12 in patients with fibromyalgia complaining of fatigue. This symptom was prevalent in our group of patients with fibromyalgia with B12 deficiency, regardless of whether the cutoff point was 400 or 350 ng/L.