Endocrine: Thyroid Flashcards by Shaquan Moore

•Drugs to treat HYPOTHYROIDISM

a. Levothyroxine
b. Liothyronine, desiccated thyroid
c. Methimazole
d. Propylthiouracil (PTU)
e. Potassium iodide
f. Radioactive Iodine

a. Levothyroxine

b. Liothyronine, desiccated thyroid

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•Drugs to treat HYPERTHYROIDISM

a. Levothyroxine
b. Liothyronine, desiccated thyroid
c. Methimazole
d. Propylthiouracil (PTU)
e. Potassium iodide
f. Radioactive Iodine

c. Methimazole

d. Propylthiouracil (PTU)

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Thyroxine (T4)
• Longer half life ~ ? days
• Pro-hormone (?potency)

Thyroxine (T4)
• Longer half life ~ 7 days
• Pro-hormone (low potency)

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? Potent (3-4 times more potent than T4)

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GOLD STANDARD:?

Thyroid Stimulating Hormone (TSH)
Other options:
T4
T3

Thyroid Stimulating Hormone (TSH)

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◦ Thyroid Stimulating Hormone (TSH)
◦ Normal Range
◦ ? to ? milliunits/L per ATI

◦ Thyroid Stimulating Hormone (TSH)
◦ Normal Range
◦ 0.3 to 5 milliunits/L per ATI

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Thyroid preparations are given to replace what the
thyroid gland cannot produce to achieve normal
thyroid levels (euthyroid to TSH?).

euthyroid

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•USED TO TREAT:
• Myxedema Coma
a. Levothyroxine
b. Liothyronine, desiccated thyroid
c.  Methimazole

a. Levothyroxine

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•MECHANISM OF ACTION:
• Simply synthetic T4 (thyroxine)
• Body will store and convert to T3 in ratios
a. Levothyroxine
b. Liothyronine, desiccated thyroid
c.  Methimazole

a. Levothyroxine

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◦ FIRST: Start low, go slow
◦ Overdose- “Hyperthyroidism
a. Levothyroxine
b. Liothyronine, desiccated thyroid
c.  Methimazole

a. Levothyroxine

b. Liothyronine, desi

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ADVERSE EFFECTS
◦ H eat intolerance
◦ E xcitement (insomnia)
◦ A ngina
◦ R estless
◦ T achycardia/Tremor
a. Levothyroxine
b. Liothyronine, desiccated thyroid
c.  Methimazole

a. Levothyroxine

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a. Levothyroxine
ADVERSE EFFECTS
HEART

◦ H eat intolerance
◦ E xcitement (insomnia)
◦ A ngina
◦ R estless
◦ T achycardia/Tremor

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ADVERSE EFFECTS Continued
◦ Boxed Warning: FDA recommends not to use as treatment for
obesity/weight loss
◦ Can see toxicity- concern with dysrhythmias like atrial fibrillation
(and other organ issues too!)
a. Levothyroxine
b. Liothyronine, desiccated thyroid
c.  Methimazole

a. Levothyroxine

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Levothyroxine
ADMINISTRATION
◦ Start with a ? dose and increase based on TSH
◦ Check a pulse before giving (hold if >?)
◦ This drug requires an ? stomach (acidic pH)
◦ Give first thing in the ?

ADMINISTRATION
◦ Start with a low dose and increase based on TSH
◦ Check a pulse before giving (hold if >100)
◦ This drug requires an empty stomach (acidic pH)
◦ Give first thing in the morning

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Do not give with cations (zinc, iron, calcium,
magnesium), these can bind to ?
This means supplements and foods-such as
milk, yogurt, etc.
a. Levothyroxine
b. Liothyronine, desiccated thyroid
c.  Methimazole

a. Levothyroxine

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Levothyroxine
Do not administer with bile acid
sequestrants (cholestyramine) separate by ?
hours- these will also bind to the drug

Do not administer with bile acid
sequestrants (cholestyramine) separate by 4
hours- these will also bind to the drug

Do not administer with bile acid
sequestrants (cholestyramine)
a. Levothyroxine
b. Liothyronine, desiccated thyroid
c.  Methimazole

a. Levothyroxine

Danger with other sympathomimetic drugs

a. Levothyroxine
b. Liothyronine, desiccated thyroid
c. Methimazole

a. Levothyroxine

Can increase the effects of warfarin

a. Levothyroxine
b. Liothyronine, desiccated thyroid
c. Methimazole

a. Levothyroxine

Educate patients that it will take several weeks to notice improvement (we generally
check levels around ? weeks after starting)

Educate patients that it will take several weeks to notice improvement (we generally
check levels around 4-6 weeks after starting)

Used when someone has an issue converting to T4 to T3
• Used when someone is not sufficiently controlled with T4
a. Levothyroxine
b. Liothyronine, desiccated thyroid
c. Methimazole

Liothyronine

Used for hypothyroidism
• Some patients prefer a more “Natural” Route
• Not recommended by Leading Associations
a. Levothyroxine
b. Liothyronine, desiccated thyroid
c. Methimazole

desiccated thyroid

Synthetic T3

b. Liothyronine, desiccated thyroid

Liothyronine

Ground down animal thyroid (pig)
◦ Ratio of 4.2:1 of T4 to T3 (does not match human ratio)
b. Liothyronine, desiccated thyroid

desiccated thyroid

``` H eat intolerance E xcitement (insomnia) A ngina R estless T achycardia/Tremor a. Levothyroxine b. Liothyronine, desiccated thyroid c. Methimazole ```

a. Levothyroxine | b. Liothyronine, desiccated thyroid

Graves’ disease HYPERTHYROIDISM or HYPOTHYROIDISM

HYPERTHYROIDISM

``` Thyroid storm (induced by stress or infection) ◦ Severe and potentially life threatening ``` HYPERTHYROIDISM or HYPOTHYROIDISM

HYPERTHYROIDISM

``` USED TO TREAT • Hyperthyroidism • Graves Disease • Thyroid Storm c. Methimazole + Propylthiouracil (PTU) e. Potassium iodide f. Radioactive Iodine ```

c. Methimazole + Propylthiouracil (PTU)

◦ Prevents coupling of iodinated tyrosine's in the thyroid c. Methimazole + Propylthiouracil (PTU)

Methimazole

``` ◦ Prevents coupling of iodinated tyrosine’s , but also prevents peripheral conversion of T4 to T3 c. Methimazole + Propylthiouracil (PTU) ```

Propylthiouracil (PTU)

``` ADVERSE EFFECTS: ◦ Liver and Bone Marrow Suppression c. Methimazole + Propylthiouracil (PTU) e. Potassium iodide f. Radioactive Iodine ```

c. Methimazole + Propylthiouracil (PTU

- BOXED WARNING- hepatotoxicity ◦ monitor for s/s, routine LFT monitor doesn't seem to help ◦ has resulted in multiple liver transplants and death c. Methimazole + Propylthiouracil (PTU) e. Potassium iodide f. Radioactive Iodine

Propylthiouracil (PTU)

``` Avoid eating foods high in iodine (seafood, soy sauce, tofu, and iodized salt) c. Methimazole + Propylthiouracil (PTU) e. Potassium iodide f. Radioactive Iodine ```

c. Methimazole + Propylthiouracil (PTU)

Monitor for Liver & Bone Marrow Suppression: ◦ leukopenia (manifested as fever, sore throat, lesions) ◦ Don’t forget other bone marrow lineages c. Methimazole + Propylthiouracil (PTU) e. Potassium iodide f. Radioactive Iodine

c. Methimazole + Propylthiouracil (PTU)

works by destroying the thyroid gland c. Methimazole + Propylthiouracil (PTU) e. Potassium iodide f. Radioactive Iodine

f. Radioactive Iodine

``` USED TO TREAT Thyroid Tumor ◦ Goiter e. Potassium iodide f. Radioactive Iodine ```

f. Radioactive Iodine

Sometimes used as marker for procedures (Diagnostic Agent) e. Potassium iodide f. Radioactive Iodine

f. Radioactive Iodine

USED TO TREAT Following radioactive iodine exposure, potassium iodide blocks the uptake of radioactive iodine by the thyroid, reducing the risk of thyroid cancer and thyroid destruction e. Potassium iodide f. Radioactive Iodine

e. Potassium iodide

◦ Nuclear Medicine testing- if target is other than the thyroid e. Potassium iodide f. Radioactive Iodine

e. Potassium iodide