Prevalence of autoimmune thyroiditis and non-immune thyroid disease in multiple sclerosis

Since multiple sclerosis (MS) and autoimmune thyroiditis (AIT) are presumed to be of autoimmune origin the correlation of these two diseases is of special interest. The aim of this study was to determine whether there are differences in the prevalence of thyroid disease with special emphasis on AIT compared with MS and normal subjects and whether the presence of thyroid disease correlates with disability, disease course, age, and disease duration. 353 consecutive patients with clinically definite MS, without interferon-beta treatment and 308 patients with low back pain or headache were extensively examined for the presence of non-immune or autoimmune thyroid disease. We found a significantly higher prevalence of AIT in male MS patients (9.4 %) than in male controls (1.9 %; p = 0.03). The prevalence of AIT in female MS patients (8.7 %) did not differ from female controls (9.2 %). Hypothyroidism, caused by AIT in almost all cases, showed a tendency to be more severe and more often present in patients with MS. There was no association between relapsing-remitting and secondary progressive disease course of MS and the prevalence of AIT. MS patients with AIT were significantly older but did not differ in disease duration and expanded disability status scale (EDSS). Further studies are warranted, to see if there is a difference in sex-hormone levels between MS patients with and without AIT and healthy controls. Longitudinal studies comparing MS patients with or without AIT could show whether there is an influence of AIT on the disease course or progression.