Endocrine Abstracts

A 31 year old female with no prior history of thyroid disease presented to hospital four days after 2nd dose Pfizer vaccination with fever, myalgia, neck discomfort and chest pain; which was relieved by sitting forwards. A small goitre and tachycardia were noted on physical examination. CXR and echocardiogram were normal. ECG revealed sinus tachycardia. Troponin T was elevated (32 ng/l, normal <5). Free T4 was raised (26.6 pmol/l, reference 10-22) with an undetectable TSH concentration. The working diagnoses were acute pericarditis/myocarditis and subacute thyroiditis. Naproxen and Carbimazole were prescribed and the patient was discharged home from the Cardiology Unit. The patient was readmitted 10 days later with symptomatic hyperthyroidism, chest discomfort, anterior neck pain and odynophagia. Clinical examination identified hyperthyroidism and a large firm tender macronodular goitre. Inflammatory markers were elevated (CRP 92, ESR 55), Thyroid function tests had deteriorated (free T4 71.8 pmol/l, free T3 19.1 pmol/l, TSH undetectable) and auto-antibodies were negative (TRAb, anti-TPO). Propranolol and Prednisolone were introduced with good symptomatic relief. Sub-acute thyroiditis classically presents with neck pain, goitre and features consistent with hyperthyroidism. It is most commonly triggered by viral infection but is a well-recognised complication associated with other mRNA vaccines. Safety data for the Pfizer vaccine has been reassuring to date, although more serious 2nd dose side-effects such as myocarditis and pericarditis have been reported. A small number of thyroiditis cases have been reported following the 2nd dose of the Pfizer-BioNTech vaccine and it has been postulated that the spike protein of the vaccine may demonstrate thyroid peroxidase molecular mimicry that could potentiate thyroiditis via this mechanism. Clinicians should be mindful of possible immune-mediated complications of vaccination as it is taken up by the wider population - as these conditions can present with non-specific symptoms, as demonstrated in this case.