Autoimmune thyroid disease in a cohort of Malaysian SLE patients: frequency, clinical and immunological associations

Autoimmune thyroid disease (ATD) has been associated with other systemic autoimmune diseases. To date, there is limited data on thyroid disorders and autoimmune thyroid disease in Malaysia. The frequency of ATD among 189 systemic lupus erythematosus (SLE) patients was 6.3%, with 2.6% in the hyperthyroid group and 3.7% in the hypothyroid group. Hypothyroidism developed at a much younger mean age (24.3 years), suggesting that SLE might be a predisposing factor for the development of Hashimoto's thyroiditis. There was a higher rate of thyroid peroxidase antibody (TPO) positivity compared with anti-thyroglobulin antibody (Tg) in the hyperthyroid subgroup. This study also demonstrated a greater proportion of ATD patients who demonstrated high titres (≥ 1:6400) of TPO compared with high titres of Tg. Although there was an association between ATD and the presence of anti-Ro/SSA and/or anti-La/SSB antibodies, the absence of sicca symptoms and negative Schirmer's tests suggest a lack of association with secondary Sjogren's syndrome. A novel association between ATD and antiphospholipid syndrome (APS) was detected in our cohort. Hence we propose that patients affected by APS be routinely screened for ATD.