Serum Thyroid Hormone Antibodies Are Frequent in Patients with Polyglandular Autoimmune Syndrome Type 3, Particularly in Those Who Require Thyroxine Treatment.

Roberto Vita,Maria Segni,Salvatore Benvenga,Marco Centanni,Marina Galletti,Maria Giulia Santaguida,Camilla Virili,Flavia Di Bari,Mattia Mandolfino

doi:10.3389/fendo.2017.00212

Abstract

Polyglandular autoimmune syndrome (PAS) type 3 consists of autoimmune thyroid disease (AITD) coexisting with ≥1 non-thyroidal autoimmune disease (NTAID) other than Addison’s disease and hypoparathyroidism. We evaluated the prevalence and repertoire of thyroid hormones antibodies (THAb) in PAS-3 patients. Using a radioimmunoprecipation technique, we measured THAb (T3IgM, T3IgG, T4IgM, and T4IgG) in 107 PAS-3 patients and 88 controls (patients with AITD without any NTAID). Based on the selective coexistence of AITD with one NTAID (chronic autoimmune gastritis, non-segmental vitiligo or celiac disease), patients were divided into group 1 (chronic autoimmune gastritis positive, n = 64), group 2 (non-segmental vitiligo positive, n = 24), and group 3 (celiac disease positive, n = 15). At least one of the four THAb was detected in 45 PAS-3 patients (42.1%) and 28 controls (31.8%, P = 0.14), with similar rates in the three PAS-3 groups. The rates of T3Ab, T4Ab, and T3 + T4Ab were similar in groups 1 and 2, while in group 3, T3Ab was undetected (P = 0.02). In PAS-3 patients, the rate of levothyroxine treatment was greater in THAb-positive patients compared to THAb-negative patients (76.7 vs. 56.1%, P = 0.03, RR = 1.4, 95% CI 1.03–1.81). Not unexpectedly, levothyroxine daily dose was significantly higher in group 1 and group 3, namely in patients with gastrointestinal disorders, compared to group 2 (1.9 ± 0.4 and 1.8 ± 0.3 vs. 1.5 ± 0.2 μg/kg body weight, P = 0.0005 and P = 0.004). Almost half of PAS-3 patients have THAb, whose repertoire is similar if chronic autoimmune gastritis or celiac disease is present. A prospective study would confirm whether THAb positivity predicts greater likelihood of requiring levothyroxine treatment.

Highlights

Polyglandular autoimmune syndromes (PAS) are defined by the coexistence of different clusters of autoimmune diseases [1]
We have shown that in PAS-3 patients, thyroid hormones autoantibodies (THAb) are found frequently, namely in 4 out of 10
By comparing data of PAS-3 patients with only Hashimoto’s thyroiditis, we infer, as mentioned earlier, that the presence of non-thyroidal autoimmune diseases (NTAID) in the background of Hashimoto’s thyroiditis adds little influence on the propensity to form THAb, with negligible influence of associated NTAID on thyroid hormones bound by THAb and classes of immunogloblulin

Summary

INTRODUCTION

Polyglandular autoimmune syndromes (PAS) are defined by the coexistence of different clusters of autoimmune diseases [1]. A decline in prevalence and serum levels of thyroid autoantibodies was noticed over the last decades in patients with Hashimoto’s thyroiditis, together with a specular increase in the prevalence of thyroid hormones autoantibodies (THAb) [6]. On the basis of the three most prevalent NTAID (chronic atrophic gastritis, non-segmental vitiligo, and celiac disease), we divided the 107 patients into three mutually exclusive groups. The control group was previously studied to serve as a control group in another setting [9] It consisted of a previously cohort of 88 Hashimoto’s thyroiditis patients (77 women, 11 men, F:M ratio = 7:1; age 42 ± 9 years) who had never been treated with levothyroxine (L-T4) and, importantly, had no NTAID.

RESULTS

DISCUSSION

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