Plasma exchanges overcome persistent iodine overload to enable 131I ablation of differentiated thyroid carcinoma.
BACKGROUND
Amiodarone has a high iodine content that can induce persistent iodine excess and may prevent radioiodine (RI) treatment.


METHODS
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 microg/24 h; normal < 150 microg/24 h), and persisted 3 months later. Plasma exchanges (PE) were prescribed.


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 (131)I). 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.
Toubert
Marie-Elisabeth
ME
Nuclear Medicine Department, Saint-Louis Hospital AP-HP, 1, avenue ClaudeVellefaux, 75475 Paris Cedex 10, France. marie-elisabeth.toubert@sls.aphp.fr
Dib-Deperrest
Anne
A
Houzé
Pascal
P
Parquet
Nathalie
N
Hindie
Elif
E
Moretti
Jean-Luc
JL
D000638:Amiodarone / Q000009:adverse effects; D000889:Anti-Arrhythmia Agents / Q000009:adverse effects; D006801:Humans; D007455:Iodine / Q000009:adverse effects / Q000097:blood / Q000652:urine; D007457:Iodine Radioisotopes / Q000009:adverse effects / Q000627:therapeutic use*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications; D010951:Plasma Exchange / Q000379:methods*; D019275:Radiopharmaceuticals / Q000009:adverse effects / Q000627:therapeutic use; D013964:Thyroid Neoplasms / Q000532:radiotherapy*; D013965:Thyroidectomy; D013997:Time Factors; D016896:Treatment Outcome
D000889:Anti-Arrhythmia Agents; D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D007455:Iodine; D000638:Amiodarone