Hashimoto thyroiditis, anti-thyroid antibodies and systemic lupus erythematosus

Area of Science:

• Endocrinology
• Rheumatology
• Immunology

Background:

• Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with complex pathogenesis.
• Thyroid dysfunction, particularly autoimmune thyroiditis, is frequently observed in patients with autoimmune disorders.
• The co-occurrence of Hashimoto thyroiditis (HT) and SLE warrants investigation due to potential shared immunological pathways.

Purpose of the Study:

• To determine the prevalence of Hashimoto thyroiditis (HT) and anti-thyroid autoantibodies (TgAb, TPOAb) in patients with SLE.
• To analyze the association between HT, anti-thyroid antibodies, and clinical/serological profiles in SLE patients.
• To evaluate the impact of HT and anti-thyroid antibodies on SLE disease activity and cumulative damage.

Main Methods:

• A cohort of 301 SLE patients and 141 controls were assessed for thyroid function and autoantibodies (TgAb, TPOAb) using chemiluminescence and immunometric assays.
• Patient records were reviewed for clinical and serological data, including SLE Disease Activity Index (SLEDAI) and Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SLICC/ACR DI).
• SLE patients were categorized based on the presence of HT, anti-thyroid antibodies, and compared across groups.

Main Results:

• The prevalence of HT was significantly higher in SLE patients (12.6%) compared to controls (5.6%, P=0.02), indicating a 2.4-fold increased risk.
• SLE patients with HT exhibited a lower incidence of malar rash (P=0.02) but a higher prevalence of anti-Sm antibodies (P=0.04).
• Anti-Sm antibodies were more common in SLE patients with two positive anti-thyroid antibodies. Neither HT nor the number of positive autoantibodies correlated with disease activity or cumulative damage.

Conclusions:

• There is a significantly increased risk of Hashimoto thyroiditis in patients with systemic lupus erythematosus.
• The presence of anti-Sm antibodies is associated with HT in SLE and may correlate with double antibody positivity.
• Hashimoto thyroiditis and associated anti-thyroid autoantibodies do not appear to influence the disease activity or cumulative damage in SLE patients.