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48 Cards in this Set

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Tyrosine and iodine form
Monoiodotyrosine (MIT)
MIT + Diiodotyrosine =
T3
DIT + DIT =
T4
What happens to T4 when it enters cells?
It is converted to T3
What happens to T3 inside the cell
Binds nuclear receptors and stimulates transcription and translation
Actions of thyroid hormone
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
Hypothyroidism in children
Cretinism
Children who had mothers w/untreated hypothyroidism
IQ avg. 7 points lower
Myxedema
Hypothyroidism in adults
Symptoms of myxedema
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
Causes of primary hypothyroidism
Idiopathic
Hashimotos (#1 in US)
131 I radioactive iodine
Inheritance or dietary iodine insufficiency
Antithyroid agents
Cause of secondary hypothyroidism
TSH def
e.g. Sheehan's syndrome
Cause of tertiary hypothyroidism
TRH
~expect low levels of TSH corrected by TRH
5 thyroid hormone preparations
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)
Treatment of choice for myxedema
Synthroid
Symptoms of Hyperthyroidism
Heat intolerance
Wt. loss
Sweating
Palpitations
Nervousness
Insomnia
Diarrhea
Most common causes of hyperthyroidism
Toxic adenoma
Grave's dz
Who gets toxic adenoma? Whats the prognosis?
Older people
Benign neoplasm, secretes xs T4 and T3
3 types of treatments for hyperthyroidism
1. (-) thyroxine biosynthesis
2. High levels of iodide
3. Radioactive iodine
6 inhibitors of thyroxine biosynthesis
1. Thiouracil
2. Thiourea
3. Methylthiuracil(Methiacil)
4. Methimazole(Tapazide)*
5. Propylthiouracil(Propacil)*
6. Mercaptomidazole
Which thyroxin inhibitor can be used in pregnancy?
Propylthiouracil only, doesn't cross placenta
*no breast feeding though
Which thyroxin inhibitors gets into breast milk?
Methimazole
Propylthiouracil
High level iodide mixtures that interfere w/thyroid gland fxn
Potassium iodide
Sodium iodide
Lugol's soln (KI and I2)
What are high level iodide solutions used in combination with?
Thiourea
Drug of choice for toxic adenoma? Contraindication
131 Iodine

NEVER DURING PREGNANCY
Drugs affecting Ca metabolism
Parathyroid hormone
Calcitonin
1,25 dihydroxycholeciferol
How does PTH increase plasma Ca
Increase bone reabsorption by activating osteoclasts

Increase syn of 1,25 (OH)2D3 in kidneys

Increase renal tubular reabsorption
How does 1,25(OH)2D3 increase plasma Ca
Increase synthesis of Ca binding transport protein in the mucosal cells of the gut

Increase Ca transport from bone
How does calcitonin decrease plasma Ca
Decrease bone reabsorption by (-) osteoclasts

Decrease tubular reabsorption of Ca
Principal regulator of PTH synthesis and release
Plasma Ca
MA of PTH
Stimulates adenyl cyclase in target tissues
Follow vit D synthesis
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
Which form of vit. D is derived from yeasts and fungi?
Ergocalciferol (D2), can be converted to 1,25(OH)2D2, used to replace 1,25(OH)2D3
Which synthetic steroid can also be used for treatment of 1,25(OH)2D3 deficiency?
Dihydrotachysterol
What does 1,25(OH)2D3 do in the cell
Binds cytosolic receptors--transported to nucleus and induces transcription
Treatment of hypoparathyroidism
Dietary Ca and 1,25(OH)2D3
i.v. PTH and Ca gluconate after surgical parathyroidectomy
Pseudoparathyroidism and treatment
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)
Treatment for rickets or osteomalacia
D2 or D3
What do you have if you have 1 alpha hydroxylase deficiency?
Treatment?
Vitamin D dependent rickets
1,25(OH)2D3
Name 4 kinds of drugs that can give drug induced osteopenia
Anticonvulsants:Phenytoin Phenobarbital
Corticosteroids
How does lg. doses of corticosteroids decrease bone mass?
(-) osteoblast differentiation and collagen synthesis
How do you treat drug induced osteopenia?
25(OH)D3, D2, or D3
How do you treat Paget's dz
Calcitonin-taken as nasal spray (not orally) called Miacalin

Bisphosphonates: sodium etidronate, alendronate, risedronate
How do bisphosphonates work? Which are recommended for Paget's?
Slow demineralization of hydroxyappetite

Alendronate and Risedronate
Osteoporosis treatment
HRT- risk of CVD
Alendronate or risedronate
Teriparatide- (+) osteoblasts
How is Teriparatide administered?
S.C. injection daily
Treatment for Vit D intoxication?
Stop Vit. D admin

Glucocorticoids (prednisone)block intestinal absorption of Ca
Primary cause of hyperparathyroidism? Treatment?
Adenoma
Surgical resection