Low-iodine diet

PCB 77 given 20 mg/kg BW 3 times over a 28-day period Thyroid hyperplasia caused by low iodine diet was not enhanced by PCB 77 14... 

In adult cattle, deficiency signs of a low-iodine diet may not appear for up to one year (Swanson 1972). Long-term iodine defi-... 

A Low-Iodine Diet Prior to Radioiodine Administration in the Management of Differentiated Thyroid Cancer... 

Preparation for Radioiodine Scans and Therapy, and the Rationale for a Low-Iodine Diet... 

There have only been a limited number of studies that have addressed the value of a low-iodine diet prior to radioiodine administration, summarized in Table 99.2. It is difficult to define the optimal extent of reduction in iodine intake and consequently urinary excretion when a low-iodine diet is used in preparation for radioiodine administration. Park and Hennessey (2004) classified a reduction in urinary iodine/creatinine ratios to <50p,g/g as excellent, and to 51—100p,g/g as adequate preparation prior to radioiodine treatment. Comparison between studies is further compfic-ated by the different measures used to measure urinary iodine, including 24 h urinary iodine, iodine/creatinine ratios and spot urine iodine measurements. Spot urinary iodine concentrations which are not normalized to urine creatinine are... 

Efficacy in reducing urinary iodine excretion Multiple studies confirm the efficacy of a low-iodine diet in reducing urinary iodine excretion. Goslings (1975), Maxon (1983a), Lakshmanan etai., (1988), Morris eta/, (2001), Pluijmen etai., (2003), Tomodaefa/, (2005). 

Morris etai., (2001) Retrospective study, n = 94. Nonsignificant increase (68% vs. 62%) in thyroid remnant ablation with low-iodine diet... 

Note-. The use of a low-iodine diet in combination with radioiodine as part of the treatment of differentiated thyroid cancer is supported by studies investigating a variety of surrogates for clinical outcomes. 

Morris et al. (2001) retrospectively reviewed the ablation rates following initial radioiodine treatment postthyroidectomy for differentiated thyroid cancer patients in a single institution in the US. In this center a written comprehensive low-iodine diet was introduced in 1996 to replace a policy of limited simple verbal advice to avoid iodized foods, enabling a retrospective comparison between two different cohorts. Successful ablation was deemed to have occurred if there was no radioiodine uptake in the area of the thyroid bed on a diagnostic uptake scan performed between 4 and 42 months post-ablation. The was no statistically significant difference in ablation rates between 50 patients treated prior to 1996 who received minimal dietary advice with a 62% successful ablation rate, and with 44 patients post-1996 who received the... 

Determining the importance of the low-iodine diet prior to radioiodine ablation therapy and scans is hampered by the limited size and retrospective nature of the studies performed. Overall these studies, with the study in the Netherlands leading the way, generally suggest that a... 

Low-Iodine Diet in Combination with rTSH and Thyroid Hormone Repiacement Prior to Radioiodine Administration... 

Although a 2-week low-iodine diet appears to be necessary when a patient is prepared for radioiodine with rTSH... 

The key features of most low-iodine diets with reference to the major sources of iodine contributing to daily iodine intake are discussed below, and are summarized in Table 99.4. As discussed, there is only limited uniformity between sources of information as to the content of a low-iodine diet, partly due to geographical and dietary variations. The recommendations of the British Thyroid Association (2002) for patients, adapted in Table 99.5, are for example not identical to the much lengthier advice provided by the Thyroid Cancer Survivors Association. Patients need to be aware that ingredient lists cannot be used reliably to determine whether a product contains significant levels of iodine. 

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