Frequency of Fibromyalgia in Hypothyroidism: A Cross-Sectional Study

Fibromyalgia is a syndrome characterized by chronic musculoskeletal pain, tenderness, and other physical symptoms. We determined the frequency of Fibromyalgia in hypothyroid patients and the relationship between FM symptoms and hypothyroid status.

The current study is a cross-sectional descriptive study investigating the prevalence and demographic characteristics of fibromyalgia in hypothyroid patients referred to University clinic in Sari in 1401-1402. Ninety-one hypothyroid patients were included in the study. The sampling method was convenience sampling. The sociodemographic features and the clinical features of hypothyroid patients were recorded. Thyroid tests included T4, TSH, and Anti Tpo Ab. Patients were examined for Fibromyalgia using American College Rheumatology (ACR) criteria for FM 2010 and 1990. For the patients who were classified as FM, the FIQR questionnaire was completed. To analyze the data, descriptive statistics indicators such as central and dispersion indicators and calculation of ratios were used, and to check the relationship between qualitative variables, chi-square test and quantitative variable comparison in different groups were used by t-tests and ANOVA in SPSS-25 software was used.

The mean age and duration of hypothyroidism were 48.35 ± 13.8 and 9.84± 6.6 years respectively. The frequency of fibromyalgia in hypothyroid patients was 7(8%) patients based on ACR 2010 criteria. In patients with hypothyroidism and fibromyalgia, 6 patients (85.7%) were positive for Anti Tpo Ab, while in patients with hypothyroidism without fibromyalgia, 29 patients (34.5%) had this antibody (P=0.007).

It seems that Anti Tpo Ab is more important than thyroid dysfunction, and it is suggested to check this antibody in fibromyalgia patients in addition to thyroid function tests.