Prevalence of autoimmune thyroid disorders in a Spanish multiple sclerosis cohort E. Munteis a , J. F. Cano b , J. A. Flores b , J. E. Martinez-Rodriguez a , M. Miret b and J. Roquer a a Neurology Service, b Endocrinology Service, Hospital Universitari del Mar, IMAS, Barcelona, Spain Keywords: multiple sclerosis, thyroid autoimmunity Received 25 January 2007 Accepted 29 May 2007 The aim of the study was to determine the prevalence of thyroid autoimmune disor- ders in a cohort of untreated multiple sclerosis (MS) patients and compare it with a stratified sample of an adult population. We prospectively studied 93 untreated MS patients. The control group included 401 healthy subjects selected by stratified sampling in a non-iodine-deficient area. Antithyroid antibodies (ATA) (antibodies against peroxidase and thyroglobulin) were considered positive at titres ‡149 IU/ml. Antibodies were positive in 11 MS patients (11.8%; 95% CI 5.3–18.4%). This pre- valence was five times higher (P ¼ 0.0001) when compared with that in the control population. We found six cases with subclinical hypothyroidism (6.45%; 95% CI 11.4–1.5) in contrast to 2.24% in the control group. Comparing MS with positive and negative ATA, there was a non-significant, slightly higher frequency of low Expanded Disability Status Scale (EDSS) score in the ATA-positive group (81% vs. 73.2%). One year after start of interferon (IFN) treatment, only one patient developed subclinical thyroid dysfunction. MS patients have a higher prevalence of ATA compared with the general population. An initial ATA and thyroid-stimulating hormone (TSH) deter- mination is recommended in all MS patients. A periodic assessment of thyroid func- tion during IFN treatment only seems to be justified in those cases where positive ATA or dysfunction is present before treatment. Introduction Multiple sclerosis (MS) is a chronic demyelinating dis- ease of the central nervous system of unknown etiology. The presence of autoantibodies and the coexistence of other autoimmune disorders in patients and first-degree relatives suggest an autoimmune physiopathological hypothesis [1–3]. Autoimmune thyroid disease is one of the most frequently studied disorders in MS patients. The presence of thyroid dysfunction and antithyroid anti- bodies (ATA) in MS patients has been assessed by several studies showing a prevalence of 2.5–10% for hormonal dysfunction [4–7] and 4–21% for antibodies [5,6,8,9]. However, some studies were performed after the start of interferon (IFN) treatment, lacked a control group [6,10], or they used patients admitted to Hospital for general consultation as controls, who are not represen- tative of the general population [4,7,8]. The aim of our study was to evaluate in our region the prevalence of thyroid autoimmune disorders in a cohort of untreated MS patients, comparing it with a stratified adult sample of the general population and to evaluate the possible influence of thyroid disorders on the clinical MS course. Patients and methods We prospectively studied consecutive patients admitted to our Neurology Department with a diagnosis of MS according to the McDonald criteria [11]. The degree of disability was assessed by the Kurtzke Expanded Dis- ability Status Scale (EDSS). None of the patients had been previously treated with IFN or immunosuppres- sant drugs. Thyroid function and ATA were evaluated at base- line in all patients before any treatment was initiated. Clinical symptoms of thyroid dysfunction were evalu- ated according to Billevicz [12] and Crooks [13] scales. The follow-up period of the study was 24 months. Pa- tients were examined every 6 months by a neurologist evaluating the presence of MS relapses, the EDSS and clinical thyroid disorders. Thyroid function and ATA were assessed again 1 year after the start of treatment in those patients who started IFN in the follow-up period. An unfavourable clinical MS course was defined as a sustained increment of at least one point in the EDSS or the need for immunomodulatory treatment based on the current criteria used by our local committee of IFN treatment. The control group included 401 healthy subjects representative of the adult population of the area of Lleida (Catalunya) [14], who were selected by stratified sampling from a study of the prevalence of goitre and Correspondence: Dra. E. Munteis, Servei de Neurologia, Hospital Universitari del Mar, IMAS. Passeig Marı´tim, 25-29, 08003 Barcelona, Spain (tel.: +34 932483235; fax: +34 932483376; e-mail: 91774@ imas.imim.es). Ó 2007 EFNS 1 European Journal of Neurology 2007 doi:10.1111/j.1468-1331.2007.01882.x