Endocrine Abstracts

A 72-year-old man with a past medical history of hypertension, atrial fibrillation and ischemic heart disease presented to cardiology outpatients for his routine visit. His regular medications included atorvastatin 80 mg daily, enalaparil 5 mg daily, amlodipine 5 mg daily, aspirin 75 mg daily and amiodarone 200 mg daily. Endocrinologists were involved after noticing abnormal thyroid function tests (TFTs) on his routine check. TFTs showed a suppressed thyroid stimulating hormone (TSH) at a level of 0.019µIU/ml (referance range 0.3-3) and elevated free thyroxine (T4) and triiodothyronine (T3) at a level of 47.58 pmol/l(11-18) and 7 pmol/l(3.5-6.5) respectively. Previous TFTs over the years were always normal. The patient was completely asymptomatic and denied any recent illness or neck pain or swelling. He has no family history of thyroid disorders and was a non-smoker. Physical examination was unremarkable with a resting heart rate of 80 beats per minute, irregularly irregular. A diagnosis of amioderone-induced hyperthyroidism (AIT) was made. He was initially started on carbimazole (CBZ) 20 mg daily and prednisolone 20 mg daily. Amioderone was stopped and atenolol at a dose of 12.5 mg daily was started after discussion with his caring cardiologist. TSH receptor antibodies came back negative and an ultrasound doppler of the thyroid gland showed a normal size gland with reduced vascularity. A diagnosis of type 2 AIT was made. Patient was reviewed after 3 weeks of treatment. He remained clinically well. Biochemically there was a slight decrease in T4, down to 36.49 pmol/land T3 down to 6.2 pmol/l. TSH suppressed at 0.008µIU/ml. CBZ was stopped and kept on the same dose of prednisolone. After 7 weeks of treatment, there was worsening in his TFTs, with T4 level of 52.18 pmol/land T3 of 9.4 pmol/l. Prednisolone was increased to 30 mg daily and kept off CBZ. After 16 weeks of treatment, T4 came down to 26.77 pmol/land T3 to 6.9 pmol/l, with TSH still suppressed at 0.008µIU/ml. During this visit, prednisolone was decreased to 20 mg daily. TFTs continued to improve gradually and became euthyroid after 5 months of treatment (TSH 0.382µIU/ml, T4 14.43 pmol/l& T3 4.9 pmol/l, currently on prednisolone 5 mg daily). A morning serum cortisol was taken more than 24 hours after his last dose of prednisolone and showed normal adrenal response with a cortisol level of 511nmol/l. Prednisolone was stop completely after a total of 26 weeks of treatment. During follow-up visits the patient remained well and TFTs remained within range.