Background: Amiodarone has a high iodine content that can induce persistent iodine excess and may prevent radioiodine (RI) treatment.
Patient: A 55-year-old obese man had taken amiodarone (200 mg/d) for 3 years and stopped 2 years earlier. He underwent total thyroidectomy for papillary cancer with extrathyroidal extension and a metastatic central lymph node, requiring RI treatment. But iodine overload, with no other documented iodinated drug intake, was found (urinary iodine excretion = 472 μg/24 h; normal < 150 μg/24 h), and persisted 3 months later. Plasma exchanges (PE) were prescribed.
Interventions and results: Eight PE over 4 weeks were needed to eliminate 39,295 nmol of iodine. Urinary iodine excretion and serum iodine concentrations, before PE and after eight sessions were, respectively: 230 and 84 nmol/mmol of creatinine, and 811 and 71 nmol/L, enabling RI treatment (4 GBq 131I). Post-therapy whole-body scan revealed cervical uptake (0.48% of the total administered dose) corresponding to usual thyroid remnants. Ablation efficacy was confirmed 6 and 24 months later by cervical ultrasonography combined with an undetectable serum thyroglobulin level after recombinant human thyrotropin stimulation.
Conclusions: When spontaneous iodine elimination is too slow to allow RI treatment of high-risk thyroid carcinoma within a reasonable time after thyroidectomy, PE are reliable and effective to overcome iodine overload.
