Thyroid Autoantibodies in Egyptian Patients with Systemic Autoimmune Connective Tissue Diseases with or without Clinical Thyroid Disorders
Authors: Mansour Howaida Elsayed , AbdElsalam Aly Safaa , Aziz Nermeen Noshy , Aziz Ayat Sami Mohamed Abdel 
Published: October 2021

Abstract

Background
Autoantibodies against the thyroid seem to be more common in patients with rheumatic diseases than in the normal population. Their appearance may be linked to an associated autoimmune thyroid disease, although sometimes they lack a clear clinical meaning. The major antigens driving the appearance of thyroid autoantibodies are thyroglobulin (Tg), thyroid peroxidase (TPO) and thyroid-stimulating hormone receptor (TSH-R).
Rheumatoid arthritis (RA) is a systemic autoimmune disease that is characterized by joint destruction and deformity, affecting millions of people worldwide. However, RA is more than a symmetrical inflammation of the joints, as increasing evidence supports a higher risk of other autoimmune disorders. Systemic lupus erythematosus (SLE) is an autoimmune disease affecting mostly joints, skin, blood vessels, heart, lungs, kidneys, liver, and nervous system, in which the immune system attacks tissues and cells leading to inflammation and damage.

Objective
To estimate the prevalence of thyroid autoantibodies among patients with systemic rheumatic disease (SLE, RA and SSc) with or without thyroid disease and its association with disease activity and functional impairment.

Patients and Methods
In the present study, we aimed to estimate the prevalence of thyroid autoantibodies among patients with systemic rheumatic diseases (SLE, RA and SSc) with or without clinical thyroid disorders and its association with disease activity and functional impairment. Our study was carried out at Ain Shams University Hospital. That was a cross sectional observational study; included 3 groups and compared with 20 healthy persons as control group;

Group I
20 patients with SLE.

Group II
20 patients with RA.

Group III
20 patients with SSc. Our patients were recruited randomly from Rheumatology Outpatient clinic and the inpatient of Internal medicine department, Ain shams University Hospital.

Results
In our study, there was no statistically significant difference between SLE patients with positive & negative thyroid Abs as regard disease activity (SLEDAI score) and SLICC/ACR damage index. No statistically significant difference between RA patients with positive & negative thyroid Abs as regard disease activity and functional impairment (measured by DAS 28 score and HAQ score respectively).And also no statistically significant difference in SSc patients with positive &negative thyroid Abs as regard disease activity and functional impairment (measured by Rodnan modified index and Medsger index respectively).

Conclusion
The prevalence of thyroid autoantibodies thyroglobulin (Tg), thyroid peroxidase (TPO) in SLE and SSc patients were higher than that with RA with and without thyroid disorders. No link could be established between the presence of thyroid autoantibodies and the results from any of the instruments used to measure inflammatory activity and functional impairment in these cases of rheumatic diseases.