Iodine available

Thyroid suppression therapy of euthyroid goiter (B). The cause of goiter (struma) is usually a dietary deficiency of iodine. Due to an increased TSH action, the thyroid is activated to raise utilization of the little iodine avail-Liillmann, Color Atlas of Pharmacology 2000 Thieme All rights reserved. Usage subject to terms and conditions of iicense. 

Derivation Passing fluorine over iodine. Available in cylinders at 98.0% min purity. 

Feinberg School of Medicine. (2006). Nutrition Fact Sheets Iodine (available at http //www.feinberg.northwestern.edu/nutrition/ factsheets/iodine.html). Northwestern University, Chicago, IL. Fineli. (2007). Foods Containing Most and Least (available at http //www.fineli.fi/ topfoods.phplcompid = 21189 lang=en), National Public Health Institute of Finland. 

General Response As far as could be assessed from the increment in body weight (BW), the decrease in iodine availability did not affect the general condition of the animals until it became severe (LID and LID with trace amounts of potassium perchlorate [LID ] groups). Despite... 

As summarized in Figure 58.1 the iodine concentration fell markedly and progressively with decreasing iodine availability. The Total T4 and T3 decreased rapidly and progressively with a five-fold decrease in iodine intake between the LID-I-5.0 and the LID-I-1.0 group. The Free T4 decreased even more markedly, whereas the Free T3 was still 25% of the control (C) values in the group with the lowest iodine availabifity. 

LID+5.0 group (C group), and then decreased to the values in the LID+0.5 and LID groups. Serum T3 was still 50% of the C value in the LID animals in whom iodine available to the thyroid gland was more than 200-fold less that that available to the C rats. 

Figure 58.6 Changes, with decreasing iodine availability, in the concentrations of T4 and T3 plasma, ovary and adrenal. The values oorresponding to C rats (LID+5.0 group) were T4 22.9 3.9ng/ml and T3 0.31 0.02ng/ml for plasma ovary 1.18 0.07ng T4 and 0.15 0.01 ng T3 adrenal 0.30 0.04 ng T4 and 0.20 0.07 ng T3. The values shown for the ovary and adrenal are the total T4 and T3 contents, as the recorded weights were considered unreliable. The meaning of symbols is the same as in Figure 58.1.

In summary, despite a 100-fold decrease in iodine availability, a combination of intra- and extrathyroidal adaptive mechanism still mitigates T3 deficiency, and presumably hypothyroidism, in most, but not all, tissues. 

As discussed elsewhere in more detail (Morreale de Escobar et ai, 2004), it is inaccurate to assume, which has been very frequently done, that inhabitants of areas of ID are chnically hypothyroid individuals. The present experimental model supports the epidemiological findings that inhabitants of areas of ID are not clinically hypothyroid individuals, as their normal circulating T3 ensures euthyroidism of most tissues by extrathyroid adaptive mechanisms known to be operative in man when iodine availability decreases. But, as shown experimentally here, this does not avoid selective hypothyroidism of tissues, such as the brain, that depend mostly on T4 for their intracellular T3 supply. This selective hypothyroidism is aheady present in conditions of mildly decreased iodine availability, and may already negatively affect mental functions (Delange, 2001 Vitti et al., 2003 Vermiglio et ai, 2004). Indeed, inhabitants of areas of ID are often described as dull. Whole populations appear to wake up when their ID — and the consequent hypothyroxinemia — are corrected (Dunn, 1992). 

Until recently, studies following the effects of enhanced supply of bromide into the body of experimental animals were carried out mostly on adult individuals and at normal iodine availability. Buchberger et al (1990) were among the first who studied the effects of chronic administration of large bromide doses on the biosynthesis of thyroid hormones in iodine-deficient rats. The results of this study... 

FOOD STANDARDS AGENCY (FSA) UK - 2000. Total Diet Study - Fluorine, Bromine and Iodine, Available from... 

The iodine available for external release is 91 per cent elemental, 5 per cent partieulate and 4 per cent organic iodide (methyl iodide). 

With only naturally occurring iodine available, it would have been impossible to detect the dynamic equilibrium. By using as a radioactive tracer, you can easily follow the substitution of radioactive iodine into the solid by measuring its increase in radioactivity. 

Kelp A seaweed that is rich in iodine. Available in tablet or powder form. As an iodine supplement to prevent a deficiency of the mineral. Very ricb source of iodine. Consumption should be limited to amounts which provide the BOA for iodine. (Toe much iodine may be toxic.)... 

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