Some patients treated with amiodarone develop hyperthyroidism. Amiodarone-induced thyrotoxicosis (AIT) consists of 2 forms that differ in underlying cause and therapy.
thyroid gland prior to amiodarone therapy
nodular goiter or "latent" Graves disease
unmasks underlying abnormal thyroid gland
destructive thyroiditis induced by amiodarone, with release thyroid hormone stores
normal, nodular or diffuse goiter; thyroid bruit or ophthalmopathy in Graves
normal or diffuse goiter
thyroid autoantibodies present
may be present in patients with underlying Graves disease
serum interleukin- 6 (IL-6)
normal to slightly increased
color flow Doppler sonography pattern
I, II or III
24 hour radioiodine uptake
low, normal or high
therapeutic response to thionamides
therapeutic response to perchlorate
therapeutic response to glucocorticoids (prednisone)
risk of hypothyroidism as sequelae
possible once thyroid hormone stores depleted
• Mixed patterns with an underlying thyroid disorder and concomitant thyroid destruction can occur).
• Radioiodine uptake in Type I disease tends to be low in areas with sufficient iodine.
• Classical symptoms of thyrotoxicosis may be absent, since amiodarone has an anti-adrenergic action and because it reduces conversion of T4 to T3.
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Specialty: Endocrinology, Clinical Laboratory