Hong Kong Med J 2010;16:434–9 | Number 6, December 2010
Amiodarone-induced thyroid dysfunction in the Hong Kong Chinese population
KF Lee, KM Lee, TT Fung
Department of Medicine and Geriatrics, Kwong Wah Hospital, 25 Waterloo Road, Hong Kong
OBJECTIVE. To determine the frequency, risk factors, clinical features, and management of amiodarone-induced thyroid dysfunctions.
DESIGN. Retrospective study.
SETTING. A regional hospital in Hong Kong.
PATIENTS. Patients who had been prescribed amiodarone for at least 6 months from 1 October 2005 to 30 September 2007.
RESULTS. A total of 390 patients (mean age, 70 years; standard deviation, 9 years; 54% male) with a median follow-up of 43 (interquartile range, 25-69) months were studied. Hypothyroidism developed in 87 (22%) of the patients (mean age, 72 years; standard deviation, 7 years; 56% male) and thyrotoxicosis in 24 (6%) of the patients (65 years; 11 years; 54% male). Increased baseline thyrotropin (thyroid-stimulating hormone) level appeared to be predictive of amiodarone-induced hypothyroidism, in which a thyroid-stimulating hormone level of 4 mIU/L or above was associated with a 4.7-fold increase in the risk (95% confidence interval, 1.9-11.7; P
CONCLUSIONS. Amiodarone-induced thyroid dysfunction is common among our population. As the clinical presentations are usually vague and atypical, regular biochemical monitoring of thyroid function is warranted, particularly in patients with elevated baseline thyroid-stimulating hormone level. The disease course of amiodarone-induced thyrotoxicosis is usually benign and remits with timely administration of anti-thyroid medications, with or without corticosteroids.
Key words: Amiodarone; Anti-arrhythmia agents; Hypothyroidism; Thyroid diseases; Thyrotoxicosis
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