Endocrine Abstracts

A 34-year-old patient was referred to the endocrinology department after a routine blood test revealed an overactive thyroid. Initially, he received Adalimumab for Crohn’s disease, but when this proved ineffective, his treatment was changed to Ustekinumab in December 2023. His past medical history includes Crohn’s disease and anxiety. He has no family history of thyroid disease. He reported worsening palpitations, feeling hot with increased breathlessness on exertion. On clinical examination, his observations were: height 182 cm, weight 73.9 kg, BMI 22.1, blood pressure 144/77, heart rate 83 beats per minute. His pulse was regular on examination and there was a mild tremor on outstretched hands. There was no sign of proptosis or ophthalmoplegia and there was no swelling of the neck. His heart sounds were normal and there were no added murmurs. Initial thyroid function tests showed a TSH 0.01 mu/L (0.27-4.2), T4 44.2 pmol/l (11.1-22), thyroid peroxidase antibodies 210 iu/ml (0-34) and positive thyroid receptor antibodies 3.5 iu/L (0-3.3). He was commenced on carbimazole 20 mg and prn propranolol which was then reduced to 10 mg daily following improvement in symptoms and thyroid function tests. Post commencing carbimazole his thyroid function tests have improved to TSH < 0.01 mu/l, T4 level 24.4 pmol/l. He is currently under routine endocrinology follow-up for on-going surveillance. Ustekinumab is a monoclonal antibody targeting interleukin-12/23 used in the treatment of psoriasis and inflammatory bowel disease. Ustekinumab’s inhibition of Th1/Th17 pathways may disrupt the Th1/Th2 balance, leading to the production of thyroid autoantibodies. Limited long-term data exist on its thyroid effects, with only two previously reported cases of ustekinumab-associated thyrotoxicosis. In conclusion, this case underscores the importance of early identification and treatment, as well as the need for further research into this association.