Endocrine Abstracts

A 77 year old female was admitted two weeks after an out-patient CT Pulmonary Angiogram showed a subsegmental pulmonary embolism and retrosternal goitre. History was of ten days of confusion, breathlessness, diarrhoea and reduced intake. On admission, she was febrile, tachypnoeic and in new, rate controlled, AF. Burch-Wartofsky Point Scale: 45, this being highly suggestive of a thyroid storm. TFTs were normal one year prior. Thyroid USS showed a multi-nodular goitre. She was commenced on propylthiouracil (PTU), beta blockers and hydrocortisone, followed by cholestyramine and Lugols iodine, but improved slowly. Nine days passed before free T4 <100 pmol/l. Following discharge after three weeks, she was readmitted with PTU induced agranulocytosis & neutropenic sepsis (Neutrophils 0.04 e⁹/l, WCC 2.0 e⁹/l) a month later. She was managed with G-CSF and IV antibiotics for cellulitis. Once stabilised, and after further steroids/lugols iodine, thyroidectomy was performed alongside ureteric stent insertion for an obstructing stone. Treatment for contrast induced thyrotoxicosis can be very difficult given the excess formed thyroid hormone present, with resultant reduced efficacy of standard anti-thyroid disease medications including carbimazole / PTU. In our case, treatment difficulties were further exacerbated/limited by PTU induced agranulocytosis. Her elevated TSH receptor/anti TPO antibody levels, and multinodular goitre, suggest pre-existing thyroid disease, with contribution of the Jod-Basedow phenomenon causing her thyroid storm, rather than a contrast induced acute thyroiditis. Contrast administration delivers large iodine loads. Approximately 35,000 mg of Iodine are given for a CTPA. Recommended daily intake is approximately 150 micrograms. Contrast induced thyrotoxicosis is more likely in iodine deficient countries (up to 0.5% vs 0.025%). Those with pre-existing thyroid disease are at increased risk. Screening is not recommended but some studies suggest uptake scintigraphy imaging can be used to stratify patients as high risk. As more CT/MRI/invasive imaging is performed & more contrast administered, we should be aware of the risks of iatrogenic thyrotoxicosis / thyroid storms, given the high mortality rates associated with this hypermetabolic state. Avoiding a storm by avoiding unnecessary imaging or optimising disease control ahead of time, is a far preferable concept, for both patient and physician.