Background The association of autoimmune thyroid disease (ATD) with non-organ specific autoimmune disorders, in particular systemic lupus erythematosus (SLE), is well recognized. Studies have shown that the prevalence of ATD is higher in SLE patients than in the general population. In addition, a significant proportion of SLE patients with ATD had subclinical thyroid disease.
Objectives To report the prevalence of autoimmune thyroid disease (ATD) in 174 Malaysian SLE patients, and its associated clinical manifestations.
Methods Medical records of all SLE patients followed in the Rheumatology Unit of Kuala Lumpur Hospital between 2011 and 2013 were reviewed. All patients had undergone thyroid function test (TFT), and history of thyroid disease was documented. SLE patients with abnormal TFT and/or positive history of thyroid disease were further tested for thyroid autoantibodies i.e. antimicrosomal antibody and antithyroglobulin antibody. Patients who were tested negative for both of these autoantibodies were further tested for thyrotropin (TSH) receptor antibody. We analysed the prevalence of ATD among SLE patients, the frequency of ATD patients with hyperthyroidism and hypothyroidism as well as type of thyroid autoantibodies, and association with clinical manifestations of SLE.
Results Of the 174 SLE patients, 11 (6.3%) had autoimmune thyroid disease. All were females. Five (45.5%) patients had hyperthyroidism, with 3 diagnosed before the onset of SLE and 2 afterwards. Six (54.5%) patients had hypothyroidism with equal number of patients diagnosed before and after the onset of SLE. One patient had subclinical hypothyroidism while the remaining 5 had overt hypothyroidism. All hyperthyroid patients were symptomatic.
The proportion of SLE patients with both antimicrosomal and antithyroglobulin antibodies were found in higher frequency (83.3%) among the hypothyroid subgroup as compared to the hyperthyroid subgroup (20%). Among the patients in the hypothyroid subgroup, only 1 out of 6 (16.7%) SLE patients had antimicrosomal antibody alone while none had antithyroglobulin antibody alone. Among the patients in the hyperthyroid subgroup, 2 out of 5 (40%) SLE patients had antimicrosomal antibody alone while 1 (20%) patient had antithyroglobulin antibody alone. One (20%) patient with hyperthyroidism had neither antimicrosomal antibody nor antithyroglobulin antibody, however had TSH receptor antibody and manifested signs characteristic of Grave's disease. Apart from ATD, 1 patient had a third autoimmune disorder, which was Addison's disease.
Eight (81.2%) of the 11 patients had mucocutaneous manifestations, 7 (72.7%) had haematological involvement, 4 (36.4%) had arthritis, 3 (27.3%) had neuropsychiatric lupus erythematosus, 2 (18.2%) had serositis, 2 (18.2%) had lupus nephritis and 1 (9.1%) had pulmonary involvement manifesting as interstitial lung disease. Two (18.2%) patients had associated antiphospholipid syndrome.
Conclusions This study showed that prevalence of ATD among Malaysian SLE patients was 6.3%, with almost equal proportion of patients with hypothyroidism and hyperthyroidism. Most of the ATD were symptomatic. In conclusion, it is prudent to screen all SLE patients for ATD.
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Disclosure of Interest None declared