Introduction: Anti-thyrotropin receptor antibodies (TSHR-Abs) stimulating the thyroid (TSAb) are responsible for Graves disease. In some patients, the TSHR-Abs can block thyrotropin action (TBAb) and cause hypothyroidism, the switch between stimulating and blocking activity in Graves disease being well. This reports aims to describe clinical presentation of patients affected directly by hypothyroidism.
Material and methods: Retrospective clinical data collection and literature review.
Results: Between 2010 and 2017 in our center, a functional bioassay assessing TSHR-Abs activity was carried out on 9 patients who did not have prior history of hyperthyroidism or ophthalmopathy. These 9 patients were diagnosed with severe hypothyroidism including a major increase in TSH [median: 125.6 μIU/ml (82132)]. Myxoedema were present in 8 patients and complicated by a cardiac tamponade in one patient. The only patient without myxedema was diagnosed and quickly treated after the onset of hypothyroidism, with a TSH level rising from 0.71 to 46 μIU/ml in two weeks. All patients had a normotrophic gland on ultrasound with features of thyroiditis in 8 patients. Interestingly, three patients had a history of BMT. Series of AITD assessing TRAbs aimed to determinate their frequency, then clinical data are lacking. In case reports describing TBAb-related hypothyroidism, we also observed patients with severe hypothyroidism.
Conclusion: Hypothyroidism induced by TSHR-Abs seems to present often with a severe hypothyroidism. Diagnosing this form could be interesting regarding the risks of switching to hyperthyroidism, orbitopathy and neonatal hypothyroidism in case of pregnancy. Prospective studies are also needed to determinate the prevalence of TBAb in severe hypothyroidism and after BMT and their clinical utility.
18 - 21 May 2019
European Society of Endocrinology