Endocrine Abstracts

Non-thyroidal illness syndrome is the alteration in thyroid function tests (TFTs) that occurs in critically ill patients, including those using thyrotoxic medications. Therefore, it is a challenge to interpret thyroid function tests in a critically ill patient on amiodarone. Case of 66-year-old male with history of heart failure with reduced ejection fraction, atrial fibrillation, and hypertension who presented to the emergency room due to progressive shortness of breath. Physical examination with tachycardia, positive jugular venous distention, crackles on pulmonary auscultation and tachypnea requiring eventual endotracheal intubation. Electrocardiogram showed atrial fibrillation with fast ventricular response. Afterwards, he was transferred to the coronary intensive care unit (CCU) where Amiodarone was started due to lack of response to other rate control medications. TFTs were requested prior initiation of amiodarone which showed thyroid stimulating hormone at 0.01 uIU/ml. During admission, patient developed ventilator associated pneumonia with subsequent septic shock. Thyroid function tests were repeated in 1 week and revealed thyroid stimulating hormone (TSH) at 0.008 uIU/ml, free T4 at 3.2 ng/dl and total T3 at 124 ng/dl. Amiodarone was discontinued and methimazole therapy was started. In the following days, clinical deterioration progressed resulting in the patient’s death. Hyperthyroidism can be significantly detrimental, particularly in critically ill patients with cardiac disease. In contrast, Non-thyroidal illness syndrome needs to be considered in patients with low/normal T3 levels which are expected to be elevated in hyperthyroidism. The most common hormone pattern of Non-thyroidal illness syndrome is low total T3 and free T3 levels, with normal T4 and TSH levels. However, patients on amiodarone therapy might present with increased free T4 levels due to decreased conversion of T4 to T3. This case illustrates the challenges of interpretation of TFTs in a critically ill patient on amiodarone.