Thyroid

Question 1

RX list

Answer 1

• L-triiodothryonine (T3)
• L-thyroxin (T4)
• Propylthiouracil
• Methimazole
• Anion inhibitors
• Iodide
• I131

Question 2

Anion inhibitors target

Answer 2

Inhibit Na/I channel

Question 3

TSH target

Answer 3

Uptake iodide, lysosome

Question 4

MMI/PTU target

Answer 4

Inhibit Iodide synthesis

Question 5

Li, high I- targets

Answer 5

Inhibit lysosomes

Question 6

Inhibit D1 activity

Answer 6

• illness
• starvation/malnutrition
• Glucocorticoids
• B-blocker
• Oral cholecystographic
• Amiodarone
• Propylthiouracil
• fatty acid
• Fetal period
• Selenium deficiency

Question 7

T4/t3 bound to

Answer 7

TBG, long half life

Pituitary responds to free, not bound

(Also albumin, TBPA = not binding as much)

Question 8

How to increase binding proteins

Answer 8

*Rx = estrogen, methadone, preg, heroin, liver dz, HIV, inheritence

LESS FREE
==> lowers free, more TSH made, free levels normalize

Question 9

How to decrease binding proteins

Answer 9

*Corticoids, androgens, danazol, asparaginase , salicylates, anti-seizure, illness

=>low binding more free, less TSH, less free

Question 10

All thyroid hormones are __ isomer

Answer 10

L

Question 11

T4 absorbed from

Answer 11

Duodenum/ileum

Question 12

More potent, higher affinity, lower circulating

Answer 12

T3

Question 13

MC adult hypothryoidism

Answer 13

Hashimoto’s = autoimmune destruction of gland

Question 14

Infantile hypo

Answer 14

CRETINISM

*neuro, deaf/mute, development

Question 15

Endemic goiter tx

Answer 15

*iodine, hasten with full replacement of thyroid hormone

Question 16

Levothyroxin sodium

Answer 16

T4 (L-Thyroxin)
TX:HYPOTHYROID
*long t1/2 = ONce per day
*S.E. = cardio, angina, palpitations

Question 17

Liothyronine sodium

Answer 17

T3 (L-triiodothyronine)
TX: HYPOTHYROID
*short half life, multiple per day
*$$, hard to monitor, CARDIOTOXIC

Question 18

THIOAMIDES: Methimazole (MMI) + Propyltiouracil

Answer 18

TX: HYPERTHYROID
THYROTOXICOSIS
*stop hormone synth (binds TPO, stops), stop idodotyrosine coupling
*3-4 weeks to start
*rapidly absorbed, concentrate in thyroid
*urine excretion
*~CURE: suppress gland 2 yrs
*S.E. = rash, joint pain, agranulocytosis
BIRTH DEFECTS

Question 19

Liotrix

Answer 19

TX: HYPOTHYROID
(T4:T3 —> 4:1)
*not necessary, body converts
*UK = better w/ D enzyme genetic issue

Question 20

Other Rx effect on T4

Answer 20

• Rifampin = clears T4
• Cholestyramine = decreased GI absorption
• preg, elderly

Question 21

Thyroid storm Tx

Answer 21

PTU + KI (suppress) + BBlocker

Question 22

Nursing mothers hyperthyroid Tx

Answer 22

PTU (but low MMI can)

Question 23

Hyperthyroid in Pregnancy Tx

Answer 23

1st trimester PTU (Less defect risk)

After: MMI (less liver tox risk)

Question 24

Refractive Hyperthyroid Tx

Answer 24

• Surgery

* radioactive iodide

Question 25

Anion Inhibitors

Answer 25

Tx: HYPERTHYROID = IODIDE (amiodarone)-INDUCED

• block iodide uptake
• S.E.: APLASTIC ANEMIA (rarely used)

Question 26

Iodide (KI)

Answer 26

TX: HYPERTHYRIOD (rare), THYROID STORM
*high iodide dose suppresses Thyroglobulin synth + lysosomes
*1st = ThyGlb suppresion (high intrathyroid iodide, Wolff-Chaikoff effect)
2nd = ThyGlb escape (low intrathyroid iodid, escape)
S.E.: rash, swollen salivary glands, mucous membrane ulcer, FETAL GOITER in PREG

Question 27

Subtotal Thyroidectomy

Pre-op Tx

Answer 27

• Thioamide until euthyroid
• KI 10 prior to reduce size/vasculature
• Bblocker = antagonize catecholamines (thyrototoxicosis)

Question 28

Radioactive Iodide (I131)

Answer 28

Tx: THYROTOXICOSIS

• oral
• to thyroid follicle, Beta particles selectively destroy gland
• 6-8 weeks —> euthyroid
• S.E.: hypothyroid, NO KIDS/PREG, no cancer risk