Autoimmune hyperthyroidism following haematopoietic stem cell transplant for multiple sclerosis in an adult female: a case report and literature review.

Summary: Haematopoietic stem cell transplant (HSCT) is a novel treatment utilised in a number of malignant and non-malignant conditions, with promising results in multiple sclerosis (MS), particularly in those not responding to previous disease-modifying therapies. There is existing evidence to suggest that HSCT has been linked to, in rare cases, autoimmune thyroid dysfunction. Much of the current literature highlights paediatric occurrences. The most common dysfunction noted is hypothyroidism, seen in 40% of cases, with other autoimmune thyroid dysfunctions reported less commonly. A 34-year-old female represents a unique case of autoimmune hyperthyroidism secondary to haematopoietic stem cell transplant completed for relapsing-remitting MS. One year following her HSCT, she presented with fatigue, brain fog, palpitations and tremors, and blood tests revealed thyrotoxicosis with elevated thyroid receptor antibody levels (TSH receptor antibodies). She was diagnosed with Graves' disease and treated with carbimazole and propranolol acutely; she is currently under regular endocrine follow-up. Ongoing multidisciplinary collaboration to holistically support her complex health needs continues, and a symptomatic improvement has been noted. Learning points: Secondary autoimmune diseases, such as Graves' disease, can develop in 2-14% of patients following autologous HSCT for MS. In our case, the timeline for development of Graves' disease post-HSCT is 10-12 months, which aligns with a previous reported case in the literature of between 8 and 32 months. Thyroid function test should be monitored regularly post-HSCT for MS as both autoimmune hyperthyroidism (Graves' disease) and hypothyroidism can develop. We aim to highlight to clinicians about this rare occurrence of Graves' disease post-HSCT.