In the context of differentiated thyroid cancer management with radioiodine, a gradual description of low iodine diets (LIDs) is undertaken. A more ample and autoexplicit one is reported, as well as the mechanisms of uptake increase, based on iodine depletion. The efficiency of LIDs in favoring iodine depletion and scanning, as potentially useful for 131I ablation, but unsettled for 131I treatment, is examined under the distress of wanting research on the subject. The usefulness of urinary iodine assay to avoid contamination, to appraise adherence to, and efficiency of LIDs, is stressed. In face of increased intake of iodine in the USA, UK and Pacific regions, it is to regret the scarce LID adoption in reports, whose credibility stands only on the belief of tacit informal LID prescription, rarely inserted in "Material and Methods". It is disapproved too the increase in 131I dose, in case of contamination, since quick depletion of iodine by LID is harmless and efficient. As there is an endemic deficiency of iodine in some regions, it is to doubt the need of LID in Brazil, where no one has been published. Nevertheless, as neither the iodine content of foods, nor the existence of fortuitous excess in some foods are known, the author dares to suggest the following algorithm: 1. To estimate populations food iodine content, or 2. To obviate contamination, by urinary iodine assay, or 3. To prescribe a LID. The author presents the axiom: "Maybe LIDs are sometimes unhelpful, contamination is always harmful."
Thyroid neoplasms; Iodine radioisotopes; Iodine; Iodine deficiency; Iodine