Endocrine Abstracts

Aim: To re-evaluate the prevalence of autoimmune associations in Hashimoto’s thyroiditis (HT).

Subjects and methods: The study was performed on 469 consecutive patients with HT and 536 without. The diagnosis of HT was based on an antithyroperoxydase antibodies (ATPO) level above 34 IU/ml. The subjects were evaluated for other associated immune diseases. The statistical analysis used the χ² test.

Results: Fifty-seven patients with HT (≈12%) associated one or more immune diseases. The most important associations were: chronic hepatitis in 13 cases (22%), vitiligo in 9 patients (17%), Biermer anemia in 6 cases (11%), rheumatoid arthritis in 5 cases (9%), diabetes mellitus type I (IDDM) in 3 patients, immune vasculitis in 2 cases. In the control group 8.3% of cases had an immune disorder. These were mainly: 16 cases with rheumatoid arthritis, 7 with hepatitis, 4 vitiligo, 3 systemic lupus erythematosus, IDDM, bronchic asthma, 2 cases with vasculitis and psoriasis. χ² test (one degree of freedom) =3.09, P=0.079. 60 patients with increased ATPO (with HT) presented also hyperthyroidism with Graves-Basedow’s disease (GBD). Prevalence was about 25%. Immune associations (other than GBD) did not modify the echographic and functional patient phenotype.

Discussions: In our previous paper (9th ECE), we found a prevalence of immune associations in HT of 15.8% compared with 5.19% in the control group. Now, in the control group we found more immune diseases. If increased ATPO levels (acting through antibody-dependent cellular cytotoxicity) mean HT and increased thyroid stimulating immunoglobulins (acting at receptor level) mean GBD, then it is obvious that there could be two distinct concomitant immune thyroid diseases.

Conclusions: Contrary to those expected and already communicated, in HT immune associations seem not to be higher than in controls, but the most common immune association in HT is GBD.