Fibromyalgia and Its Endocrine Comorbidities

A study from Israel takes a closer look at the association between fibromyalgia and endocrine disorders, including thyroid dysfunction, diabetes, pituitary and adrenal disorders, metabolic bone diseases, and vitamin D deficiency.

Patients with fibromyalgia have a significantly higher prevalence of endocrine comorbidities compared with healthy controls, suggesting overlapping pathophysiological mechanisms, the findings from a recent study suggest

The Bottom Line

• A new population-based, case-control study matched adults with fibromyalgia by age and sex to control subjects without fibromyalgia in a 1:5 ratio.
• Compared to controls, individuals with fibromyalgia had higher rates of endocrine comorbidities, including osteoporosis and diabetes mellitus type 1 and 2.
• The findings suggest that it may make sense for clinicians to initiate routine endocrine screenings in their patients with fibromyalgia.
• Although prior studies have reported associations between fibromyalgia and selected endocrine disorders, comprehensive large‐scale analyses across a broad range of endocrine comorbidities are lacking,” Magen and colleagues, a team of experts based in Israel, noted in Clinical Endocrinology. “Our study addresses this gap.
• Characteristics of the study population

  This observational, population-based, case-control study included 9232 adults with fibromyalgia ages 18 to 90 years who were compared with 46,160 age- and sex-matched individuals without fibromyalgia.

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  Patients were members of a large, nationwide health maintenance organization. Throughout the study, fibromyalgia diagnoses were confirmed by board-certified rheumatologists using American College of Rheumatology criteria.

  Average age (47.6 years) and sex (86.8% female) were balanced between individuals with and without fibromyalgia. There were no significant differences by age category or socioeconomic status.

• Patients with fibromyalgia had a higher average body mass index (28.5 versus 27.6 kg/m2; P<.001), with obesity reported in 36.6% of individuals with fibromyalgia compared with 30.2% without it (odds ratio [OR] 1.34, 95% confidence interval [CI] 1.28 to 1.40; P<.001). Additionally, more patients with fibromyalgia, compared with those without fibromyalgia, said they currently smoke: 21.4% versus 17.0% (OR 1.33, 95% CI 1.26 to 1.41; P<.001).

  A greater prevalence of endocrine comorbidities

  Patients with fibromyalgia had significantly more-frequent diagnoses of several thyroid disorders compared with healthy controls, as follows (P<.001 for all):

  • Hashimoto’s thyroiditis: 13.3% versus 10.0% (OR 1.38, 95% CI 1.29 to 1.48)
  • Graves’ disease: 4.1% versus 3.0% (OR 1.38, 95% CI 1.22 to 1.55)
  • Thyroid nodules: 13.3% versus 7.1% (OR 2.01, 95% CI 1.87 to 2.16)
  • Multinodular goiter: 8.1% versus 4.9% (OR 1.72, 95% CI 1.57 to 1.87)

  Less-common thyroid conditions were also more frequently reported among patients with fibromyalgia, with varying effect sizes, and some associations did not achieve statistical significance. For instance, type 1 and 2 diabetes were significantly more common among patients with fibromyalgia compared with healthy controls; however, no differences were observed for gestational diabetes.

  • Type 1 diabetes: 0.90% versus 0.25% (OR 3.64, 95% CI 2.72 to 4.87; P<.001)
  • Type 2 diabetes: 23.5% versus 18.6% (OR 1.34, 95% CI 1.27 to 1.42; P<.001)
  • Gestational diabetes: 1.6% versus 1.8% (OR 0.89, 95% CI 0.74 to 1.06; P=.241)
  • Regarding adrenal disorders, Cushing’s syndrome (OR 5.01, 95% CI 2.14 to 11.72; P<.001) and Addison’s disease (OR 2.73, 95% CI 0.83 to 8.05; P=.050) were more frequently diagnosed among patients with fibromyalgia, whereas rates of primary aldosteronism and pheochromocytoma were not significantly different.

    Other significant differences, in prevalence of pituitary and parathyroid disorders, polycystic ovary syndrome, and metabolic bone and mineral disorders, were reported in patients with fibromyalgia versus those without fibromyalgia, as follows:

    • Prolactinoma: 0.28% versus 0.16% (OR 1.81, 95% CI 1.11 to 2.87; P=.014)
    • Primary hyperparathyroidism: 1.9% versus 1.1% (OR 1.75, 95% CI 1.46 to 2.09; P<.001)
    • Polycystic ovary syndrome: 1.1% versus 0.8% (OR 1.36, 95% CI 1.08 to 1.70; P=.045)
    • Osteoporosis: 19.1% versus 11.6% (OR 1.80, 95% CI 1.69 to 1.91; P<.001)
    • Paget’s disease of bone: 0.16% versus 0.05% (OR 3.00, 95% CI 1.47 to 5.93; P=.002)
    • Vitamin D deficiency: 39.9% versus 30.3% (OR 1.53, 95% CI 1.46 to 1.60; P<.001)

    Limitations and final thoughts

    In this study, Magen and colleagues demonstrated a significant association between fibromyalgia and endocrine disorders, including a higher prevalence of thyroid dysfunction, diabetes, pituitary and adrenal disorders, and metabolic bone and mineral diseases, among individuals with fibromyalgia compared with age- and sex-matched healthy controls.

  • These findings support the concept of fibromyalgia as a systemic condition with frequent endocrine comorbidities,” the authors noted. “However, causality cannot be inferred, and the associations may reflect shared risk factors rather than direct mechanistic links.”

    Limitations of the study include its retrospective design; reliance on ICD-9 codes for diagnoses, without imaging or laboratory confirmation; the possibility of detection bias, since patients may have been evaluated more frequently than controls; and lack of generalizability due to the study population being drawn from a single healthcare system in Israel.

    “This study highlights the considerable burden of endocrine disease in fibromyalgia, reframing fibromyalgia as a condition with both neuroimmune and endocrine dimensions,” the authors concluded. “Future research should focus on prospective longitudinal studies to clarify temporal and causal pathways, explore mechanistic links between endocrine dysfunction and fibromyalgia, and identify therapeutic targets that may improve outcomes.

  • reference<https://www.medpagetoday.com/resource-centers/fibromyalgia-focus/fibromyalgia-and-its-endocrine-comorbidities/6240