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Element 53Where does it exist in nature?Other FactsUses of IodineThe ThyroidThe Thyroid 2Iodine and the Thyroid GlandIodine and the Thyroid Gland 2Iodine and the Thyroid Gland 3Iodine and the Thyroid Gland 4What happens when you don’t consume enough iodine?Iodine deficiency disorders: MalformationsIodine Deficiency Disorders (I.D.D.): StatisticsWhat causes I.D.D.?Case Study: Iodine Deficiency and England in the 20th CenturyCase Study: Maring of New GuineaEvidence from Research in GeochemistryHow do you know if you have I.D.D.?More Research Methods: Clinical Assessment of Iodine StatusNormal Clinical Values of Iodine for Healthy AdultsWhat does this all mean?Preventative MeasuresSummary and ConclusionIODINEPresentation byChristopher LoveIAP2006, 12.091 Medical Geology/GeochemistryMassachusetts Institute of TechnologyJanuary 30, 2006Element 53 Greek---‘iodes’---meaning violet Group 17/VII of the periodic table---halogen Atomic weight is 126.9045 grams Melting point is 113.7 ˚C Boiling point is 184.4 ˚C Bernard Courtois discovered iodine in 1811Where does it exist in nature? Iodide ions in brines  An impurity in Chile saltpeter  Main natural source of iodine is kelp 2000 kg seaweed = 1 kg iodineOther Facts Elemental iodine is produced by oxidation with chlorine  It produces a variety of colors in organic solvents Starch is a common indicator Be careful with handling!Uses of Iodine Silver iodide is used in photography  Disinfectant for external wounds  Essential trace element  Iodine is used by the thyroid glandThe Thyroid Largest endocrine gland in the body Synthesizes and stores thyroid hormones: thyroxine (T4) and 3,5,3΄-triiodothyronine (T3)  Located in the neck 2 lobes connected by a narrow isthmus Composed of functional units called folliclesThe Thyroid 2http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/Pictures/Thyroid_gland_explained?OpenDocumentIodine and the Thyroid Gland Normal adult thyroid weighs 20-25g and contains 8-10 mg of iodine Iodine contributes to 65% of T4 molecular size and 59% of T3 molecular size Iodine provides the raw material for hormone synthesis Most ingested iodine is reduced in the gastrointestinal tract and absorbed almost completelyIodine and the Thyroid Gland 2  Iodate Æ iodide Æ completely absorbed Thyroid selectively concentrates iodide in amts. required for adequate hormone synthesis Most of the remaining iodine excreted in urineIodine and the Thyroid Gland 3Iodine in the thyroid gland+ complex series of reactions= thyroid hormonesIodine and the Thyroid Gland 4 Deiodinase helps to recycle iodine within the thyroid gland Thyroid-stimulating hormone (TSH) is the major regulator of thyroid function Pituitary secretes TSH in response to concentrations of thyroid hormone Elevated serum TSH concentration indicates primary hypothyroidism Decrease in TSH concentration reflects hyperthyroidismWhat happens when you don’t consume enough iodine?Iodine Deficiency DisordersIodine deficiency disorders: Malformations Fetus: abortion, perinatal death, infant death, neurological cretinism, severe mental deficiency, deaf-mutism, spastic deplegia,squint, myxedeatous cretinism, growth-stunting, severe mentaldeficiency, psychomotor deficiency Neonate: goiter, hypothyroidism Child and adolescent: hypothyroidism, mental deficiency, low physical development Adult: goiter, mechanical compression of adjacent organs in the neck,endocrine disorders (hyperthyroidism/hypothyroidism), neoplasia(benign tumors/cancer), mental deficiencySource: Essentials of Medical Geology, pg. 190, Table XIodine Deficiency Disorders (I.D.D.): Statistics In 1990, the U.N. and W.H.O. estimated that about 1 billion people are at risk for I.D.D. 211 million with goiter 5.1 with cretinism Mean IQ loss of 13.5 points in the population living in severely iodine deficient areas  Iodine deficiency is the greatest cause of preventable brain damage in childhoodHistorical Advances Chinese were treating goiter with powdered seaweed and sea urchins several thousand years ago BCE: Greeks used burst sponge to treat goiter 1811: discovery of iodine by adding concentrated H2SO4to a seaweed of the type that was used to treat goiter 1819: Fyfe identified iodine in sponge 1820: Coindet treated goiter with iodine 1854: Chatin suggested low iodine in soil, water, and food caused goiter 1896: Baumann showed that the thyroid is rich in iodine; Halsted showed that maternal thyroid removal caused fetal thyroid hyperplasia in dogs 1908: McCarrison characterizes endemic cretinism 1909: Marine shows that maternal iodine deficiency caused goiter in the fetus (dog)Historical Advances, con’t 1915: Kendall discovers thyroxin 1917: Smith shows that maternal iodine deficiency caused “cretinism”(swine) 1921: Marine shows that goiter can be prevented by iodide 1927: Harrington synthesizes thyroxin 1941: Mackenzie shows that sulfanilguanidine inhibits iodide concentration by thyroid (rat) 1943: Mackenzie shows that aminobenzene and thiourea inhibit iodine concentration by thyroid (rat); Mackenzie reveals hyperplasia of pituitary gland in hypothyroid state (rat)Source: Essentials of Medical Geology, pg 190, Table IXWhat causes I.D.D.? Not enough iodine intake Cause: low iodine concentration in soil Goiter: thyroid gland becomes enlarged in an attempt to be more efficient Brain damage: iodine deficiency impairs certain aspects of lipid metabolism in the developing mammalian brainCase Study: Iodine Deficiency and England in the 20thCentury 1920s British research: iodine supplementation reveals improved livestock reproductive performance Rise of the iodine content in milk Government policies of increased consumption of milk Endogenous infant mortality rates decrease as iodine intake increasesCase Study: Maring of New Guinea Georgeda Buchbinder, Department of Anthropology, Queens College Endemic goiter and endemic cretinism a by-product of culture contact Substitution of non-iodized trade salt for locally manufactured salt that was high in iodineEvidence from Research in Geochemistry Geographically defined---high mountain ranges, rain shadow areas, and central continental regions Little iodine in the secondary environment is derived from weathering of the lithosphere Iodine concentration


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