Nonorgan-Specific Antibodies in Thyroid Disease, Autoimmune Disorders

Investigators have identified a link between autoimmune thyroid disease (ATD) and multiple nonorgan-specific antibodies, leading to various rheumatic diseases including rheumatoid arthritis (RA) in patients, according to research published in Medicine.

Basant M. Elnady, MD, of the Department of Physical Medicine and Rheumatology at Benha University, Egypt, and colleagues, conducted a 2-phase study of patients with autoimmune thyroid disease to determine the prevalence of various nonorgan-specific antibodies and elucidate the link between antibodies and the occurrence of rheumatic disease.

Sixty-one patients with ATD (65.6% >18 years of age, 83.6% female) who tested positive for antithyroid antibodies and 61 age- and sex matched control subjects (mean age 27±14.9 years) without thyroid, connective tissue, or autoimmune diseases were enrolled in the study.

During phase 1—a case control study—all 61 patients underwent assessment for the presence of antinuclear antibodies (ANA), antidouble-stranded deoxyribonucleic acid (anti-dsDNA), antiextractable-nuclear antigens (anti-ENAs), rheumatoid factor (RF), and anticyclic-citrullinated peptides (anti-CCP). 

During the phase 2 longitudinal clinical follow-up, all patients were followed for 2 years to assess their risk of developing autoimmune diseases.

Within the ATD group, Dr Elnady and colleagues found the highest percentage of ANA (50.8%), followed by RF (34.4%), anti-ENA (21.3%), and anti-CCP (19.7%). During the 2-year follow-up, nearly one-third (32.8%) developed a rheumatic disease: 45% RA, 20% systemic lupus erythematosus (SLE), 10% Sjögren syndrome (SS), and 25% Behcets disease, fibromyalgia, mixed connective tissue disease, and Rhupus syndrome (a combination of lupus and RA), combined.

The researchers also found that patients within the ADT group had a significantly higher prevalence of antibodies than the control group.

Patients who developed rheumatic diseases were overwhelmingly female (85%), older than 18 years, and had the highest percentage of ANA antibodies (55%). 

Summary and Clinical Applicability

ANA—the most frequently identified nonorgan-specific antibody—can be detected in a wide range of autoimmune disorders, including SLE, progressive systemic sclerosis, juvenile idiopathic arthritis (JIA) and autoimmune hepatitis.

Dr Elnady and colleagues noted that this prospective study is—to the best of their knowledge—the first to use nonorgan-specific antibodies to detect the risk of autoimmune disease development. “Our study’s comparable results showed that patients of ATD and positive anti-dsDNA have [a] 2.45 times risk [of developing] rheumatic disease,” they wrote.

“It was obvious in our study that ATD is more associated with rheumatic diseases than previously thought,” Dr Elnady and colleagues concluded. “Early referral to rheumatologists is needed to differentiate the extra glandular ATD manifestations from true associated autoimmune disease. More large-cohort longitudinal studies with stratification of the studied group…are needed to establish this concept in routine serological testing for ATF patients.”

Limitations and Disclosures

• Stratification of the cohort according to age is still needed to further examine the necessity of routine serological testing for ATD patients

The authors report no funding or conflicts of interest.

Reference

Elnady BM, Kamal NM, Shaker RHM, et al. Prevalence and clinical significance of nonorgan specific antibodies in patients with thyroiditis as predictor markers for rheumatic diseases. Medicine. 2016;95(38):e4336. doi: 10.1097/MD.0000000000004336

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