Two Weeks of a Low-Iodine Diet Are Equivalent to 3 Weeks for Lowering Urinary Iodine and Increasing Thyroid Radioactive Iodine Uptake

Morsch, Eveline Predebon; Vanacor, Roberta; Furlanetto, Tânia Weber; Schmid, Helena

doi:10.1089/thy.2010.0232

Cited by 20 publications

(18 citation statements)

References 14 publications

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“…We hypothesize that one of the reasons for these equivalent data between 15-and 30-day RID is the lack of compliance of patients who went on an RID for 30 days, which made the UI results in this group similar to those of the patients who went on the diet for 15 days. Our results confirm the findings of Morsch et al [34] , who compared RID for 2 and 3 weeks and observed a significant UI decrease in both groups, with no difference between them.…”

Section: Discussionsupporting

confidence: 92%

Assessment of the Effect of Two Distinct Restricted Iodine Diet Durations on Urinary Iodine Levels (Collected over 24 h or as a Single-Spot Urinary Sample) and Na+/I- Symporter Expression

et al. 2015

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pression before and after the RID. Results: Of 306 patients, only 125 properly complied with both the RID and 24U collection. We observed a correlation between sU and 24U UI before the RID (n = 306, ρ = 0.47, p < 0.001), after a 15-day RID (n = 79, ρ = 0.49, p < 0.001), and after a 30-day RID (n = 46, ρ = 0.73, p < 0.001). There was a significant decrease in UI after the RID. The median UI measurement was 275 μg/l at baseline and 99 and 80 μg/l after a 15-and 30-day RID, respectively. There was a significant increase in NIS expression after a 15-day RID. Conclusions: A 15-day RID is sufficient to deplete the iodine pool. sU can replace 24U UI as a marker for assessing the iodine pool. NIS expression was increased after a 15-day RID.

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Section: Discussionsupporting

confidence: 92%

Assessment of the Effect of Two Distinct Restricted Iodine Diet Durations on Urinary Iodine Levels (Collected over 24 h or as a Single-Spot Urinary Sample) and Na+/I- Symporter Expression

et al. 2015

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“…However, no studies have convincingly demonstrated whether an adequate or slightly elevated iodine nutritional status has a negative impact on the treatment of hyperthyroidism. A single recent study compared the impact of an iodinerestrictive diet for 2 or 3 weeks on patients referred for investigation based on suppressed TSH levels associated with thyroid nodules and goiters (17). In this study, 2 and 3 weeks of a LID similarly decreased urinary iodine levels by 60%, which was accompanied by an approximately 40% increase in 131 I uptake by the thyroid.…”

Section: Discussionmentioning

confidence: 76%

“…To increase 131 I uptake, a stringent low-iodine diet (LID) is recommended and its efficacy is easily monitored by measuring urinary iodine levels (17,18). A LID reduces plasma iodine levels, leading to increased expression of sodium-iodide symporter (NIS), thereby increasing 131 I uptake (19,20).…”

Section: Introductionmentioning

confidence: 99%

Low iodine diet does not improve the efficacy of radioiodine for the treatment of Graves’ disease

Santarosa

Orlandi

Fiorin

et al. 2015

Arch. Endocrinol. Metab.

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Objective: Consuming a low-iodine diet (LID) is a widely accepted practice before administering radioiodine ( 131 I) to evaluate and to treat thyroid disease. Although this procedure is well established for the management of patients with differentiated thyroid cancer, its use in patients with benign disease is unclear. So, we aimed to evaluate the influence of a LID on the outcome in patients with Graves' disease (GD) treated with 131 I. Subjects and methods: We evaluated 67 patients with GD who were divided into 2 groups: one group (n = 31) consumed a LID for 1-2 weeks, and the second group (n = 36) was instructed to maintain a regular diet (RD). Results: The LID group experienced a 23% decrease in urinary iodine after 1 week on the diet and a significant 42% decrease after 2 weeks on the diet. The majority (53%) of the patients in the LID group had urinary iodine levels that were consistent with deficient iodine intake. However, there was no difference in the rate of hyperthyroidism's cure between the LID and the RD groups 6 months after 131 I therapy. Furthermore, the therapeutic efficacy did not differ in patients with varying degrees of sufficient iodine intake (corresponding urinary iodine levels: < 10 μg/dL is deficient; 10-29.9 μg/dL is sufficient; and > 30 μg/dL is excessive). Conclusion:In the present study, we demonstrated that although a LID decreased urinary iodine levels, those levels corresponding with sufficient or a mild excess in iodine intake did not compromise the therapeutic efficacy of 131 I for the treatment of GD. Arch Endocrinol Metab. 2015;59(6):501-6

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“…Among studies that examined the LID, varying degrees of detail were provided about the implemented LID protocols. However, strict prohibition of all seafood and avoidance of all dairy products were commonalities observed among existing protocols . Many studies also restricted the consumption of canned foods as well as eating out at restaurants.…”

Section: Methodsmentioning

confidence: 99%

“…The current literature supports 1–2 weeks as the length for LID. There appear to be little to no benefit from greater than 2 weeks of a LID, as one study showed that the proportion of patients with UIC <100 mcg/l on a 3‐week LID (60·9%, n = 25) was not significantly different from that of patients on a 2‐week LID (63·2%, n = 21, P = 0·96) . Lastly, intense patient education and improved accessibility to medical staff may improve LID success rates and allow for a reduction in LID duration to 1 week, even in iodine‐replete areas.…”

Section: Methodsmentioning

confidence: 99%

Low iodine diet in differentiated thyroid cancer: a review

Bansal

et al. 2015

Clinical Endocrinology

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SummaryRadioactive iodine (RAI) ablation is a beneficial, adjuvant therapy for the management of differentiated thyroid cancer (DTC) after thyroidectomy. The goal of RAI is to destroy remnant thyroid and microscopic cancerous tissue. Radioactive iodine uptake is enhanced by elevating TSH levels and initiating a low iodine diet (LID) prior to ablation. An ideal LID should preferably not exceed 50 mcg/day of dietary iodine for 1-2 weeks, although the duration may be shortened to a week with a structured patient education programme. A pre-ablation spot urinary iodine concentration (UIC) of <100 mcg/l and/or a urinary iodine to creatinine ratio (UICR) of <100 mcg/gCr would support an adequate LID preparation. Hyponatraemia, most likely due to iatrogenic hypothyroidism, is a potential side effect associated with LID and occurs during and a few days after the LID. Although the overall incidence of hyponatraemia is low, patients at high risk (older age, female sex, use of thiazide diuretics) may benefit from serum sodium monitoring. The existing evidence on the impact of LID on RAI ablation has been largely inconsistent due to retrospective study designs and the lack of an objective measurement of urinary iodine levels. Future large prospective randomized control trials are needed to elucidate and confirm the crucial role of LID in achieving successful RAI ablation and greater disease-free survival in DTC.

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Two Weeks of a Low-Iodine Diet Are Equivalent to 3 Weeks for Lowering Urinary Iodine and Increasing Thyroid Radioactive Iodine Uptake

Cited by 20 publications

References 14 publications

Assessment of the Effect of Two Distinct Restricted Iodine Diet Durations on Urinary Iodine Levels (Collected over 24 h or as a Single-Spot Urinary Sample) and Na<sup>+</sup>/I<sup>-</sup> Symporter Expression

Assessment of the Effect of Two Distinct Restricted Iodine Diet Durations on Urinary Iodine Levels (Collected over 24 h or as a Single-Spot Urinary Sample) and Na<sup>+</sup>/I<sup>-</sup> Symporter Expression

Low iodine diet does not improve the efficacy of radioiodine for the treatment of Graves’ disease

Low iodine diet in differentiated thyroid cancer: a review

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