Suppression of Thyroid Radioiodine Uptake by Various Doses of Stable Iodide

Abstract

We studied the effect of various doses of sodium iodide on thyroid radioiodine uptake in euthyroid volunteers by giving single doses of 10, 30, 50, and 100 mg and then daily doses of 10, 15, 30, 50, or 100 mg for 12 days thereafter. All single doses above 10 mg suppressed 24-hour thyroid uptake of 123I to 0.7 to 1.5 per cent. Continued daily administration of 15 mg of iodide or more resulted in values consistently below 2 per cent. A small but statistically significant fall in serum thyroxine (T4) and triiodothyronine (T3) and a rise in serum thyrotropin (TSH) concentrations were observed after eight and 12 days of iodide treatment. These data suggest that the thyroid uptake of radioactive iodine can be markedly suppressed by single-dose administration of 30 mg of stable iodide and that suppression can be maintained with daily doses of at least 15 mg. This study provides guidelines for stable iodide prophylaxis in the event of exposure to radioactive iodine.

Pilot study of urinary iodine concentration and of biochemical thyroid parameters before and after cautious public health intervention on salt iodide content: The Swiss longitudinal 1996–2000 iodine study

“…Correcting iodine deficiency (ID) in particular, especially in the event of exposure to radioactive iodine, is such a sound investment in both health and social development (Sternthal et al, 1980;Report ETA, 1985;Tiwari et al, 1996;Van den Briel et al, 2000;Als et al, 2002;Black, 2003) that 'yin medical history, iodine prophylaxis has an unsurpassed cost-benefit advantagey' (David Marine, Chicago, 1920s). In populations with severe ID, reversibility of profound hypothyroidism could indeed be obtained with as little as a single injection of iodized oil, even at low doses (Tonglet et al, 1992).…”

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“…Iodide-131 and Iodide-123 Positive: reduce the uptake Sternthal et al (1980) Perchlorate and pertechnetate ions…”

Radiopharmaceuticals drug interactions: a critical review

“…Inorganic iodine-containing medications such as Lugol's iodine as well as some vitamin/mineral supplements, are thought to release iodine thereby decreasing the specific activity of iodide in the body pool. This would also decrease uptake of radioiodine into the thyroid gland (Sternthal et al 1980, Laurie et al 1992. Similarly, use of mitomycin C decreased the uptake of 99m Tc-GHA by the thyroid (Gomes et al 2001).…”