Features of type 1, type 2, and mixed amiodarone-induced thyrotoxicosis
| Type 1 AIT | Type 2 AIT | Mixed AIT | |
|---|---|---|---|
| Mechanism of disease | Excess iodine | Destructive inflammatory thyroiditis | Features of both |
| Underlying thyroid disease | Present | Absent | Features of both |
| Goiter | Multinodular or diffuse goiter normally present | Infrequent; may have small, diffuse, firm, or tender goiter | Features of both |
| TSH, early disease course | Elevated | Normal | Variable |
| TSH, late disease course | Elevated | Normal | Variable |
| Thyroid autoantibodies | Present | Absent | Features of both |
| Radioactive iodine studies | Normal or increased uptake | Little or no update | Features of both |
| 99mTc-MIBI | Increased uptake | Decreased uptake | Features of both |
| Color-flow Doppler ultrasonography | High vascularity | Absent vascularity | Features of both |
| Treatment | Thionamides | Steroids | Combination of both |
| Spontaneous remission | No | Possible | Features of both |
| Late hypothyroidism | No | Extremely rare | Features of both |
99mTc-MIBI = technetium Tc 99m methoxyisobutylisonitrile; TSH = thyroid-stimulating hormone