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34 Cards in this Set
- Front
- Back
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What is the leading cause of preventable mental retardation?
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Iodine deficiency
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how is Iodate metabolized?
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Through reduction to iodide. Then iodide is taken up by kidney and thyroid through iodine pumps. TSH regulates iodine pumps.
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What hormones does iodine help produce?
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T4 - thyroxine
T3 - triiodothyronine T3 and T4 are a mix of monoiodotyrosine and diiodotyrosine |
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preceding hormones
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TSH and TRH, Thyroid stimulating hormone and Thyrotropin releasing hormone
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T3 and T4 circulate primarily as what?
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TG, or thryroglobulin
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What conditions affect TBG levels of total T4?
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T4 increased by estrogens and acute hepatitis
T4 decreased by glucocorticoid therapy, illness, nephrotic syndrome |
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Brain development role of Iodine Hormones
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Not enough thyroid hormones during pregnancy --> mental retardation
T3 regs specific brain genes: 1st phase= 3rd - 5th month gestation. 2nd phase=glial cell multiplication |
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Goiter
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Enlarged thyroid gland --> Response to insufficient iodine.
Less T4 leads to Increased TSH, which causes hyperplasia of thyroid to increase uptake of iodine |
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How to distinguish goiter
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lateral lobes larger than terminal phalanx of thumb
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Clinical manifestations of IDD
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Cretinism, - physical and neurological manifestations
Neurological cretinism: normal stature, mental retardation, squint, deaf-mute, motor spasticity Hypothyroid cretinism: severe growth retard, mental retard, coarse, dry skin |
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Sources of iodine
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Seaweeds, seafoods
iodized salt plants in iodine-rich soils |
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Methods of assessing iodine status
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-Urinary iodine concentration
-Serum TG -Goiter rate -Serum TSH (indirect) |
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How is thyroid measurement done?
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By palpitation and by thyroid ultrasound
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What indicates severe iodine deficiency?
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less than 20 micrograms per liter
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EFFECTS OF IODINE DEFICIENCY THROUGH THE LIFE CYCLE
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Childhood: Decrease intellectual function, somatic growth impaired, increased TSH can lead to increased CVD risk.
Adult: iodine deficiency (mid-moderate) leads to thyroid cancer, diffuse goiter, nodular goiter |
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An inherited zinc disorder
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Acrodermatitis enteropathica: defect in zinc absorption, growth retardation, treatable with supplemental zinc
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Absorption of Zn
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Absorbed by passive diffusion - carrier on brush border of intestinal cells - called transmucosal transport
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What increases and decreases Zinc absorption?
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Increased: CAPi: amino acid, picolinate
Decreased: POF: Phytic acid, oxalic acid, fiber |
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Condition where excessive Zn causes copper deficiency
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Sideroblastic anemia
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Zn distribution, by percentage
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Skeletal muscle, then bone, then blood, then skin
Also: choroid of eye and prostatic fluid have highest concentration |
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Role of Zn in immunity
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Helps block HIV from entering the cell.
Also, zinc deficiency leads to lower T and B cell function. |
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Causes of Zn deficiency
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low intake
Absorption interference imparied utilization high requirements Humid climate (sweat) genetic disease |
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Zn interactions with other nutrients
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may cause Copper deficiency
High iron reduces Zn absorption high calcium intake --> reduce Zn absorption Zn is component of retinol binding protein. needed for enzyme converting retinol to retinal. low zn can lead to night blindness. |
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Clinical manifestations of ZD
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-growth retard, alopecia, delayed sex mat, skin lesions, night blindness, diarrhea,
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Individuals at risk
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infants and children, pregnant women, patients receiving intravenous feeding, alcoholic liver disease ppl, older adults.
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Evaluation of Zn status
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plasma or serum levels.
hair zinc concentration also: taste acuity, immune status |
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Prevention of Zinc deficiency
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zinc supplements, exclusive breast feeding, food prep that reduces phytates
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What is the most common cause of anemia?
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Iron deficiency
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Where is greatest overlap of iron def, anemia, and IDA?
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with hookworm infested populations: high blood loss, absorbability is low.
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Causes of anemia
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usually iron def, then malaria, vit A, folic acid, vit B12
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Factors contributing to ID&A
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pregnancy, prematurity, LBW, rapid growth, low meat consumption, menstruation, phytate consumption, nematode infection
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Major regulator of Iron
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Hepcidin.
Hemojuvelin regulates Hepcidin. |
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Consequences of Iron deficiency
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Anemia, increase risk LBW, dec psychomotor develop, inc risk depression, dec work performance, inc risk heavy metal poisoning (lead)
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Tests for iron deficiency
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Hemoglobin
Seum ferritin Serum transferrin receptor |
