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Flashcards in Thyroid Deck (16):
1

thyroid hormones

T3 (triodothyronine)/T4 (tetraiodothyronine): O2 consumption; heat production; carb/fat/protein metabolism; growth & differentiation; stimulation growth hormones

2

biosynthesis of thyroid hormones

iodide uptake by NIS -> oxidation of iodide: T1 (MIT) & T2 (DIT) formed -> coupling to form T3 & T4 -> reabsorption of thyroglobulin (Tg) -> proteolysis of Tg; release of T3 & T4 -> de-iodination of MIT and DIT and recycling of iodide -> conversion of T4 to T3

3

functions of throid hormones

metabolism (uptake of free glucose + others); cardiovascular (incr HR/CO/O2 consumption/vasodilation); CNS - mental acuity; growth (neurogenesis & skeletal formation) cretinism: congenital hypothyroid (maternal) - stunted growth and retardation

4

hypothyroid

hashimoto; iatrogenic (caused by a treatment); congenital; pituitary disorder; pregnancy (autoimmune); iodine deficiency; risks: >60 women; autoimmune disease; +family history; hyperthyroid treatment

5

hypothyroid signs/symptoms

fatigue; dryness; cold intolerance; weight gain; goiter; depression

6

Thyroid Drugs

liothyronine (cytomel); desiccated thyroid (armour thyroid); levothyroxine

7

Liothyronine

synthetic T3; can become toxic; more potent than T4 - sold in combo (liotrix); no evidence of beneficence

8

Desiccated Thyroid (Armour Thyroid)

T4/T3 naturally derived combo from pigs; possible antibody rxn; not stable; variable levels

9

Levothyroxine

Synthetic T4; highly protein bound (1/2 life 7 days); dose varies by patient (50 mcg/day long standing disease or older/25 mcg/day with cardiac disease then increased by 25 mcg/mo to decrease stress on heart); lots of drug interactions - take on empty stomach

10

Hyperthyroid Causes

grave's disease; toxic mutinodular goiter; toxic adenoma; thyroiditis; risks: >60; prev thyroid problems; +history; high iodine intake; pregnancy in last 6 mo

11

Hyperthyroid signs/symptoms

weight loss; heat intollerance; palpitations, anxiety; wetness

12

Antithyroid Drugs

thioamides: methimazole; PTU details: treatment until remission (12-18 mo); preg cat D; inhibit iodine organification; effects take 4 weeks due to T4 stores

13

Methimazole

FIRST CHOICE (except preg & thyroid storm); less risk liver damage; tid until euthyroid then once daily

14

Propylthiouracil (PTU)

USED IN PREGNANCY - more prodein binding so doesn’t cross placental barrier as easily; thyroid storm; MAY SEVERE HEPATITIS; q8h

15

Thioamide Side Effects

nausea; GI; altered taste/smell; rash; fever; rare: AGRANULOCYTOSIS! - sore throat/high fever signs; vasculitis; urticarial rash

16

Hyperthyroid Tx Options

surgery; radioactive destruction (131 I); propranolol in acute phase; diltiazem if B-blocker contraindicated