A patient started on amiodarone develops a transient fall in serum T4 and T3 levels over the following days, which later escapes back toward baseline despite continued drug intake. Which physiologic phenomenon explains this sequence?
- A Jod-Basedow phenomenon
- B Wolff-Chaikoff effect followed by escape ✓
- C TSH receptor antibody stimulation
- D Peripheral conversion of T4 to reverse T3
Correct answer: B. Wolff-Chaikoff effect followed by escape
Explanation
An acute surge in intracellular iodide transiently inhibits thyroid peroxidase-mediated organification and hormone synthesis, the Wolff-Chaikoff effect. In normal glands the sodium-iodide symporter downregulates within days, iodide levels fall, and organification resumes, producing escape. The Jod-Basedow phenomenon is the opposite event, iodine-induced hyperthyroidism in autonomous tissue, so option A describes increased rather than decreased output.
Reference: Williams Textbook of Endocrinology, 14th ed.
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