Iodine metabolism

Taurog A (2000) Thyroid hormone synthesis Thyroid iodine metabolism. In Braverman LE, Utiger RD (eds) Werner and Ingbar The thyroid. Lippincott Williams Wilkins, Philadelphia, PA, pp 61-85... 

Daburon, F., G. Fayart, and Y. Tricaud. 1989. Caesium and iodine metabolism in lactating cows under chronic administration. Sci. Total Environ. 85 253-261. 

J. R. Arthur, F. Nicol, G. J. Beckett, The role of selenium in thyroid hormone metabolism and effects of selenium deficiency on thyroid hormone and iodine metabolism, Biol. Trace Elem. Res., 33 (1992), 37-42. 

Cobalt most often depresses the activity of enzyme including catalase, amino levulinic acid synthetase, and P-450, enzymes involved in cellular respiration. The Krebs citric acid cycle can be blocked by cobalt resulting in the inhibition of cellular energy production. Cobalt can replace zinc in a number of zinc-required enzymes like alcohol dehydrogenase. Cobalt can also enhance the kinetics of some enzymes such as heme oxidase in the liver. Cobalt interferes with and depresses iodine metabolism resulting in reduced thyroid activity. Reduced thyroid activity can lead to goiter. 

T3) within the protein backbone of the thyroglobuiin protein in the follicular lumen. Endocytosis followed by proteolytic cleavage of thyroglobuiin releases the iodothyronines into the circulation. A schematic outline of iodine metabolism, with emphasis on the formation and secretion of thyroid hormones, is shown in Figure 52-3. 

Eales, J.G. Iodine metabolism and thyroid-related functions in organisms lacking thyroid follicles are thyroid hormones also vitamins Proc. Soc. Exp. Biol. Med. 214 302-317, 1997. 

Taurog, A. Hormone synthesis thyroid iodine metabolism. In Werner and Ingbar s the Thyroid, 8th edition, edited by L.E. Braverman and R.D. Utiger, New York, Lippincott, Williams and Wilkins, pp. 61—84, 2000. 

Cavalier RR. Iodine metabolism and thyroid physiology Current concepts. Thyroid 1997 7 177-181. 

Behne S, Kyriakopoulos A, Gessner H, et al. 1992. Type I iodothyronine deiodinase activity after high selenium intake, and relations between selenium and iodine metabolism in rats. J Nutr 122 1542-1546. 

Zagrodzki P, Szmigiel H, Ratajczak R, et al. 2000. The role of selenium in iodine metabolism in children with goiter. Environ Health Perspect 108(1) 67-71. 

It had been reported earlier (Uthus and Nielsen 1990, Nielsen 1991) that vanadium-deficient nutrition of rats led to increased thyroid weights and thyroid bo-dyweight ratios, and decreased growth. These studies showed that stress factors which alter thyroid status or iodine metabolism also enhance the response to vanadium deprivation. Indeed, it is possible that vanadium is essential in the control not only of certain enzyme reactions but also thyroid metabolism. 

JuGOv VK and Sidora VD (2000) Condition of a function of iodine metabolism and cancer morbidities in locales of the Poltava area, population which one use water with different contents of a fluorine. Ukrainian Radiol J 8 330-331 (in Ukrainian). 

Pavelka S, Babicky A, Vobegky M and Lener J (1999) Effect of high dose of bromide on iodine metabolism in the rat. In Romancik V, ed. Industrial Toxicology, pp. 224-228. Slovak Technical University, Bratislava. 

Miller JK, Swanson EW (1967) Performance and iodine metabolism of dairy cattle with iodine 131 irradiation. J Dairy Sci 50 90-94. 

FIGURE 56-2 Adapted, widi permission, from Taurog A Hormone synthesis thyroid iodine metabolism. In Werner and Ingbar s The Thyroid, Th ed. LE Braverman, RD Utiger (eds). Philadelphia, Lippincott Williams Wilkins, 1996. 

Mathematical Models of Human Iodine Metabolism, Including Assessment of Human Total Body Iodine Content... 

Perhaps the most ambitious early effort of this type was the model of iodine metabolism developed by Douglas Riggs (1952). He presented a theoretical model that included ingestion of iodine as iodide, its absorption into the plasma, and transfer to the thyroid and other tissues, with loss through the kidneys, sweat and expired air. Within the thyroid gland, he described the organification of iodine and production of monoiodothyronine, diiodothyronine, and thyroxine (T4) on the framework of thyroglobufln. 

Figure 19.1 The simplified model of human iodine metabolism presented by Riggs (1952).

However, by combining all organified iodine compounds in his model, he accounted for its metaboflsm. The basic structure for understanding human iodine metabolism presented by Riggs remains helpful. 

Figure 19.2 The thyroid portion of the comprehensive model of human iodine metabolism presented by Berman et ai, (1968). The thyroid is modeled as a series of compartments with progressively slower patterns of thyroid hormone manufacture and release.

Figure 19.7 A model of iodide (inorganic iodine) metabolism, showing the gastrosalivary diversion pattern.

A model, when applied to tracer studies, provides an insight into internal processes that could not otherwise be measured without perturbing the organism, and thus interfering with its physiology. These studies have contributed greatly to our understanding of human iodine metabolism. 

We provided evidence for a marked interference of excessive bromide intake in adult male rats with their whole-body metabolism of iodine (cf. Chapter 61, this volume). Here, we extend our overview on the effects of a high bromide intake in lactating rat dams on their own iodine metabolism, and on the well-being of the afflicted young. There are two main routes of iodine elimination from the... 

The exact mechanism(s) of bromide interference with iodine metabolism and with postnatal developmental processes in the young remains unresolved. 

Pregnancy has an effect on other thyroid functions, with significant changes in iodine metabolism and clearance. This is particularly relevant in areas deficient in iodine. 

Environmental goitrogens may normally be ineffective when in low concentration, and most are not of major clinical importance unless there is coexisting iodine deficiency. However, a vegan diet is likely to include more foods possessing goitrogenic properties, such as brassicas and seaweed, compared with an omnivorous diet, and previous research has shown that vegans are at increased risk of iodine deficiency. Thus, excess intake of these substances may affect iodine metabolism in vegans. 

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