Thyroid Dysfunction in Patients with Systemic Lupus Erythematosus, Correlation with Disease Activity

Abstract

Background: The relationship between autoimmune thyroid disease and systemic lupus erythematosus (SLE) has been revealed but the prevalence of thyroid disease in lupus patients is controversial. The aim of this study is to assess thyroid dysfunction and the presence of anti-thyroid antibodies in patients with SLE, and its association with disease characteristics and disease activity. Methods: Sixty patients with SLE ≥ 18 years who satisfied the American College of Rheumatology (ACR) criteria and thirty age and sex matched normal volunteer were included, all underwent laboratory evaluation for serum free T3, free T4, TSH, Antithyroglobulin antibody (Ab TG) and Antithyroid peroxidase antibody (Ab TPO). Clinical and serological characteristics and disease activity of SLE were assessed; correlation with thyroid dysfunction was studied. Results: 2(3.33%) patients had subclinical hyperthyroidism, 24 (40%) were euthyroid, 12 (21.67%) had subclinical hypothyroidism and 22 (35%) had overt hypothyroidism. All the control group was euthyroid. The patients with thyroid dysfunction had more arthralgias, arthritis, changes of voice, bowel habits and weight, irregular menstruation, sleep disturbance, nervousness and tremors than the euthyroid lupus patients (p<0.05). The lupus patients with subclinical and overt hypothyroidism had statistically significant higher Ab TG than the euthyroid patients and patients with subclinical hyperthyroidism and control group (p<0.05) but no statistically significant difference between all groups as regard Ab TPO. SLE patients with subclinical & overt hypothyroidism had statistically significant higher ESR and SLAM score than the euthyroid patients and patients with subclinical hyperthyroidism (p<0.05). There was a positive correlation between Ab TG levels and body mass index BMI, ESR and disease activity measures by SLAM score (p<0.05). Conclusion: The thyroid dysfunction is more frequent in SLE patients than control group. Subclinical and overt hypothyroidism are more likely to occur in SLE patients. There are a positive correlation between Ab TG level and disease activity and negative correlation with free T3 & free T4.