Endocrine Abstracts

Background: The prevalence of hypothyroidism is around 1–2% in the UK. Hashimoto’s thyroiditis is thought to cause 0.1–2% of overt disease and 10–15% of subclinical hypothyroidism. This case presents a patient with severe hypothyroidism, secondary to Hashimoto’s thyroiditis, found incidentally on a surgical admission. The case study discusses the challenges and management of severe hypothyroidism in the need for an acute surgical intervention.

Clinical case: A 72 year-old man was brought into the Emergency Department after a road traffic accident. He was found to have right tibial and fibular shaft fractures, and was incidentally discovered to have sinus bradycardia secondary to profound hypothyroidism. Thyroid function tests done on admission showed a thyroid stimulating hormone (TSH) level of 227 mIU/l (0.27–4.2 mIU/l) and free T4 level of 0.8 pmol/l (12–22 pmol/l). Anti-thyroid peroxidase antibody (anti-TPO) level was >1300 IU/ml (positive if >100 IU/ml), suggestive of Hashimoto’s thyroiditis. The patient underwent two surgeries for fixation of fractures, whilst having thyroid hormone replacement. Oral levothyroxine was started and up titrated according to clinical and biochemistry response. Intravenous liothyronine was also used intraoperatively for management of bradycardia and reducing the risk of myxoedema coma.

Discussion and conclusion: Surgery and anaesthesia can precipitate complications associated with hypothyroidism, such as cardiovascular collapse, respiratory failure, and worryingly,myxoedema coma. Altered respiratory physiology and renal clearance of drugs also increase patients’ sensitivity to drugs commonly used in anaesthesia. It is recommended to postpone elective surgeries until a euthyroid state can be achieved, through thyroid hormone replacement. Urgent or emergency surgical admissions should be managed with awareness of complications. Mild or moderate hypothyroidism should be managed with hormone replacement therapy and can continue with surgery. NICE Guidelines recommend treatment of hypothyroidism with levothyroxine replacement. Combination therapy with liothyronine should only be used in selective cases and directed by accredited endocrinologists. Although there is a lack of outcome data to guide management of severe hypothyroidism requiring urgent surgical management, studies support, and have shown success in, the use of combination therapy of levothyroxine and liothyronine to reduce risk of severe complications,particularly myxoedema coma. Our case demonstrates an example of an approach to the management of profound hypothyroidism associated with bradycardia and the risk of developing myxoedema coma. Whilst the patient remained bradycardic intraoperatively, he did not suffer from cardiovascular collapse or develop myxoedema coma. He subsequently recovered uneventfully from both surgeries with no serious surgical complications associated with hypothyroidism.