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48 Cards in this Set
- Front
- Back
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Tyrosine and iodine form
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Monoiodotyrosine (MIT)
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MIT + Diiodotyrosine =
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T3
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DIT + DIT =
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T4
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What happens to T4 when it enters cells?
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It is converted to T3
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What happens to T3 inside the cell
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Binds nuclear receptors and stimulates transcription and translation
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Actions of thyroid hormone
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Increased O2 consumption by cells
Regulate lipid and CHO metabolism Enhance cell growth and development Promote development of CNS Increased heat production Increased heart rate and contractility Increased CHO, protein, and lipid metabolism Increased cholesterol metabolism |
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Hypothyroidism in children
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Cretinism
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Children who had mothers w/untreated hypothyroidism
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IQ avg. 7 points lower
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Myxedema
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Hypothyroidism in adults
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Symptoms of myxedema
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Sensation of cold-dry skin
Edema of eyelids Puffiness of hands/feet/face Skin pallor Thinning/dryness/loss of hair Lethargy Fatigue Slowed speech Poor memory, anxiety, decreased reflexes, bradycardia, hoarseness, wt. gain, constipation, menstrual abnormalities |
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Causes of primary hypothyroidism
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Idiopathic
Hashimotos (#1 in US) 131 I radioactive iodine Inheritance or dietary iodine insufficiency Antithyroid agents |
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Cause of secondary hypothyroidism
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TSH def
e.g. Sheehan's syndrome |
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Cause of tertiary hypothyroidism
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TRH
~expect low levels of TSH corrected by TRH |
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5 thyroid hormone preparations
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1. Thyroid USP (desiccated thyroid)
2. Thyroglobulin 3. Sodium levothyroxine, USP (Synthroid) 4. Sodium liothyronine (Cytomel)(T3) 5. 4:1 mixture T4:T3 (Liotrix Euthyroid, Thyrolar, overpriced) |
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Treatment of choice for myxedema
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Synthroid
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Symptoms of Hyperthyroidism
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Heat intolerance
Wt. loss Sweating Palpitations Nervousness Insomnia Diarrhea |
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Most common causes of hyperthyroidism
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Toxic adenoma
Grave's dz |
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Who gets toxic adenoma? Whats the prognosis?
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Older people
Benign neoplasm, secretes xs T4 and T3 |
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3 types of treatments for hyperthyroidism
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1. (-) thyroxine biosynthesis
2. High levels of iodide 3. Radioactive iodine |
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6 inhibitors of thyroxine biosynthesis
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1. Thiouracil
2. Thiourea 3. Methylthiuracil(Methiacil) 4. Methimazole(Tapazide)* 5. Propylthiouracil(Propacil)* 6. Mercaptomidazole |
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Which thyroxin inhibitor can be used in pregnancy?
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Propylthiouracil only, doesn't cross placenta
*no breast feeding though |
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Which thyroxin inhibitors gets into breast milk?
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Methimazole
Propylthiouracil |
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High level iodide mixtures that interfere w/thyroid gland fxn
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Potassium iodide
Sodium iodide Lugol's soln (KI and I2) |
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What are high level iodide solutions used in combination with?
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Thiourea
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Drug of choice for toxic adenoma? Contraindication
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131 Iodine
NEVER DURING PREGNANCY |
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Drugs affecting Ca metabolism
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Parathyroid hormone
Calcitonin 1,25 dihydroxycholeciferol |
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How does PTH increase plasma Ca
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Increase bone reabsorption by activating osteoclasts
Increase syn of 1,25 (OH)2D3 in kidneys Increase renal tubular reabsorption |
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How does 1,25(OH)2D3 increase plasma Ca
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Increase synthesis of Ca binding transport protein in the mucosal cells of the gut
Increase Ca transport from bone |
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How does calcitonin decrease plasma Ca
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Decrease bone reabsorption by (-) osteoclasts
Decrease tubular reabsorption of Ca |
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Principal regulator of PTH synthesis and release
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Plasma Ca
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MA of PTH
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Stimulates adenyl cyclase in target tissues
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Follow vit D synthesis
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1. 7 dehydrocholesterol (in skin) converted to cholecalciferol (vit D3) by UV light
2. D3-- 25(OH)D3 in liver 3. 25(OH)D3-- 1,25(OH)2D3 in kidneys by 1-alpha-hydroxylase |
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Which form of vit. D is derived from yeasts and fungi?
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Ergocalciferol (D2), can be converted to 1,25(OH)2D2, used to replace 1,25(OH)2D3
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Which synthetic steroid can also be used for treatment of 1,25(OH)2D3 deficiency?
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Dihydrotachysterol
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What does 1,25(OH)2D3 do in the cell
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Binds cytosolic receptors--transported to nucleus and induces transcription
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Treatment of hypoparathyroidism
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Dietary Ca and 1,25(OH)2D3
i.v. PTH and Ca gluconate after surgical parathyroidectomy |
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Pseudoparathyroidism and treatment
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PTH normal Ca low, due to insensitvity to PTH (may be b.c. of defective Gs)
Treat w/1,25(OH)2D3 (won't necessarily fix bone dz) |
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Treatment for rickets or osteomalacia
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D2 or D3
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What do you have if you have 1 alpha hydroxylase deficiency?
Treatment? |
Vitamin D dependent rickets
1,25(OH)2D3 |
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Name 4 kinds of drugs that can give drug induced osteopenia
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Anticonvulsants:Phenytoin Phenobarbital
Corticosteroids |
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How does lg. doses of corticosteroids decrease bone mass?
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(-) osteoblast differentiation and collagen synthesis
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How do you treat drug induced osteopenia?
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25(OH)D3, D2, or D3
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How do you treat Paget's dz
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Calcitonin-taken as nasal spray (not orally) called Miacalin
Bisphosphonates: sodium etidronate, alendronate, risedronate |
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How do bisphosphonates work? Which are recommended for Paget's?
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Slow demineralization of hydroxyappetite
Alendronate and Risedronate |
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Osteoporosis treatment
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HRT- risk of CVD
Alendronate or risedronate Teriparatide- (+) osteoblasts |
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How is Teriparatide administered?
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S.C. injection daily
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Treatment for Vit D intoxication?
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Stop Vit. D admin
Glucocorticoids (prednisone)block intestinal absorption of Ca |
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Primary cause of hyperparathyroidism? Treatment?
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Adenoma
Surgical resection |
