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8/6/2019 Iodine Seminar (Somya Srivastava and Smriti Datta)
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We owe a great many thanks to a great many peoplewho helped and supported us during this seminar.
My deepest thanks to our lecturers, dr. Amrit pal KaurMam, Mr. Jai dev Singh sir and Mr. HimanshuKumar Sarathe sir.
We express our thanks to our dean dr. N.D.Shashikaran sir.
And lastly our families who supported us through and
through.
Thanking you.
Smriti Datta (79).
Somya Srivastava (80).B.D.S. Ist year.
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What are minerals?
Classification of minerals
Iodine Sources : rich, good and poor sources
RDA
Absorption, storage and transport
Plasma iodine Biochemical requirements
Biosynthesis of thyroid hormones
Deficiency disease
Toxicity
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A mineral is a naturally occurring solid
chemical substance that is formed through
geological processes and that has acharacteristic chemical composition, a highly
ordered atomic structure, and specific
physical properties
The study of minerals is called Mineralogy.
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Minerals
Principal Elements
Also called Macrominerals.
Required in amounts greater than 100 mg/day.
(Ca, P, Mg, Na, K, Cl, S)
Trace Elements
Also called Micro minerals.
Required in amounts less than 100 mg/day.
Essential Trace Elements
( Fe, Cu, I, Mn, Zn, Mo, Co, F, Se, Cr)
Possibly Essential Trace Elements
(Ni, V, Cd, Ba)
Non-Essential T race Elements
(Al, Pb, Hg, B, Ag, Bi)
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Iodine is an essential trace element.
The total body contains about 20mg iodine,
most of it (80%) being present in the thyroidgland.
Muscle, salivary glands and ovaries alsocontain some amount of iodine.
It is a bluish-black solid.
It is seen apparently sublimating at normaltemperature into a violet-pink gas that hasan irritating odour.
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Rich sources:
Seafood
Sea vegetables
Table salt
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Good sources:
Cod
Sea bass
Perch
Haddock
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Poor sources:
Dairy products
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RDA for In Micrograms Per Day
Infants 40
Children 60 - 110
Men 110 - 150
Women 80 - 115
Pregnant women 125
Lactating women 150
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Iodine as iodide is mainly absorbed from
small intestine.
Normally, about 30% of dietary iodine is
taken up by the intestinal cells.
Iodine absorption also occurs through skin
and lungs.
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About 80% of bodys iodine is stored in theorganic form as iodothyroglobulin (a
glycoprotein) in the thyroid gland. This protein contains thyroxine, diiodotyrosine
and triiodothyronine in different proportions.
Excretion of iodine mostly occurs through
kidney. It is also excreted through saliva, bile, skin,
and milk (in lactating women).
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The normal concentration of plasma iodine is4-10 mg/dl.
Most of this is present as protein boundiodine (PBI) and represents the iodinecontained in the circulating thyroidhormones.
PBI level decreases in hypothyroidism andincrease in hyperthyroidism.
RBC do not contain iodine.
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The only known function of iodine is itsrequirement for the syntesis of thyroid
hormones namely, thyroxine (T4) andtriiodothyronine (T3).
These hormones are involved in severalbiochemical functions.
Functionally, T3 is more active than T4. Stimulates metabolic activities and increases
oxygen consumption in most of the tissues ofthe body (except brain, lungs, testes and
retina).
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Uptake of iodide:
The uptake of iodide by the thyroid gland
occurs against a concentration gradient(about 20:1).
It is an energy requiring process and islinked to the ATPase dependent sodium-
potassium pump. Iodide uptake is primarily controlled by TSH.
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Antithyroid agents such as thiocynate andperchlorate inhibit iodide transport.
Formation of active iodide:
Thyroid is the only tissue that can oxidize I- toa higher valence state I+.
This reaction requires Hydrogen peroxide andis catalysed by the enzyme thyroperoxidase.
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NADPH dependent system supplieshydrogen peroxide.
TSH promotes the oxidation of iodide toactive iodine while the antithyroid drugs(thiourea, thiouracil, methinazole) inhibit.
Thyroglobulin and synthesis of T3 andT4:
Thyroglobulin contains about140 tyrosineresidues which can serve as substrates foriodine for the formation of thyroidhormones.
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Tyrosine (of thyroglobulin) is first iodinated at
position 3 to form monoiodotyrosine (MIT)
and then at position 5 to form diiodotyrosine(DIT).
Two molecules of DIT couple to form
thyroxine (T4).
One molecule of MIT, when coupled with one
molecule of DIT, triiodothyronine (T3) is
produced.
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GOITER: Any abnormal increase in the sizeof the thyroid gland is known as goiter.
Enlargement of thyroid gland is mostly tocompensate the decreased synthesis ofthyroid hormones and is associated withelevated TSH. Goiter is primarily due to a
failure in the auto regulation of T3 and T4synthesis. This may be caused by deficiencyor excess of iodine.
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SIMPLE ENDEMICGOITER: This is due toiodine deficiency in the diet. It is mostly found
in geographical regions away from sea coastwhere the water and soil are low in iodinecontent. Consumption of iodized salt isadvocated to overcome the problem of
endemic goiter. In certain casesadministration of thyroid hormone is alsoemployed.
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CRETINISM:Cretinism is a condition
associated with iodine deficiency and goiter,
commonly characterized by mentaldeficiency, deaf-mutism, squint, disorders of
stance and gait, stunted growth and
hypothyroidism.
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Excess iodide (more than 1.1 mg/day) hassymptoms similar to that in iodine deficiency.
Commonly encountered conditions areabnormal growth of thyroid gland anddisorders in the functioning of the organismas a whole.
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Biochemistry by U.Satyanarayan and U.
Chakrapani
Wikipedia
Internet
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