Thyroid and Anti Thyroid Drugs Flashcards

1
Q

what are the thyroid hormones

A

T3 - Liothyronine (triiodothyronine)

T4 - Levothyroxine (thyroxine)

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2
Q

what are the thyroid hormones used for? (name them)

A

Liothyronine and Levothyroxine

Cretinism (thyroid hormone synthesis defect - kid hypothyroidism)
adult hypothyroidism (myxedema)
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3
Q

AE of thyroid hormones

A

tremors, tachycardia, arrhythmias, heat intolerance

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4
Q

what are the different levels of hypothyroidism

A

primary - due to thyroid itself not producing T3 or T4 as seen in Hashimoto’s thyroiditis –> anti TPO with Iodine deficiency

secondary - due to pituitary - low TSH

tertiary - due to hypothalamus - low TRH

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5
Q

features of hypothyroidism

A

weight gain, cold intolerance, bradycardia, constipation, poor memory, hoarse voice, Queen Anne’s sign

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6
Q

what is Queen Anne’s sign

A

thinning of hair in lateral third of eyebrows

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7
Q

presentation of cretinism

A
6 Ps
Pot belly
Pale
Puffy faced child
Protruding Umbilicus
Protuberant tongue
Poor brain development (mentally retarded)
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8
Q

causes of cretinism

A

lack of dietary iodine
defect in T4 synthesis
developmental failure of thyroid

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9
Q

some causes of hyperthyroidism

A
Grave's
Toxic multinodular goiter
Toxic adenoma
Molar pregnancy
Post partum thyrotoxicosis
Post viral thyroiditis
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10
Q

presentation of hyperthyroidism

A
weight loss
heat intolerance
palpitation
bowel frequency
insomnia
abnormal menses
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11
Q

drugs used for hyperthyroidism

A

BIT DIG

Beta blocker: propanol and esmolol
131-I
Thioamides: Propythiouracil and Methimazole

Diatriazote
Iodine and Iodine salts: Lugol solution and Potassium Iodide
Glucocorticoids

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12
Q

what are thioamides and what other names are they called and why

A

Propythiouracil (PTU) and Methimazole

AKA goitrogens because they can cause goiter

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13
Q

mechanism of thioamides (name them)

A

Propythiouracil and Methimazole

block iodination of thyroglobulin and inhibit coupling reaction of DIT with MIT (to form T3) or with another DIT (to form T4) by inhibiting the enzyme used, TPO –> thyroperoxidase

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14
Q

why do thioamides have a slow onset of action

A

they inhibit formation of newly formed T3 and T4 by inhibit TPO, thyroperoxidase

they don’t inhibit the preformed thyroid hormones so takes about 2-3 weeks to see full effect

propythiouracil does inhibit formation of T3 from T4 (but not methimazole)

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15
Q

why is propythiouracil (PTU) preferred over methimazole during thyroid storms and in preggos

A

it also has inhibitory effect on 5-deiodinase so T4 cannot be turned to active T3

also less teratogenic so used in pregnancy

SN: most thyroid hormones released are T4 and need to be activated/deiodinated to T3 to be active

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16
Q

AE for thioamides (name them)

A

propythiouracil and methimazole

HHARV

Heptotoxicity
Hypoprothrombinemia
Agranulocytopenia
Rash
Vasculitis
17
Q

AE seen with methimazole

A

Teratogenic – not used in pregnancy

Aplastic Cutis Congenita (absence of hair and epidermal layer of skin on head)

18
Q

What are the iodine and iodine salts

A

Lugol solution

Potassium Iodide

19
Q

mechanism of iodine and iodine salts (name them)

A

lugol solution and potassium iodide

large amount of iodine –> TPO thyroperoxidase inhibition –> inhibit thyroid hormone synthesis –> decrease organification and release —> Wolff Chaikoff Effect

also reduce size and vascularity of hyperplastic glands

20
Q

when does Wolff Chaikoff effect wear off? What happens after it wears off?

A

it wears off after 10-14 days –> Jod Basedow Effect which is hyperthyroidism after administering iodine –> goiter

hence Iodine and its salts are used short term

21
Q

AE of iodine and iodine salts (name them)

A

lugol solution and potassium iodide

CABE
Chronic Iodide intoxication
Anaphylactoid reaction - angioedema and swelling
Brassy taste and Burning of teeth and gums
Enlargement of parotid and maxillary glands

22
Q

mechanism of radioactive 131-I

A

taken up and sequestered in thyroid gland –> damages tissues by emitting toxic beta rays –> only damages thyroid tissue

23
Q

AE of 131-I

A

hypothyroidism

24
Q

contraindication of 131-I

A

pregnant women

nursing mothers

25
Q

what are beta blockers used for in hyperthyroidism (name them)

A

propanolol (inhibits T4 to T3) and esmolol

control nervousness, palpitation, fatigue, weight loss, heat intolerance, and tremors

26
Q

what can you give to patients who have asthma or COPD and cannot tolerate beta blockers

A

give them CCB Diltiazem or Verapamil

27
Q

other than propythiouracil, what inhibits peripheral conversion of T4 to T3

A

PA-DIGS

Propanolol
Amiodarone

Diatrizoate
Iohexol
Glucocorticoids
Sodium Iodide IV

28
Q

drugs that inhibits iodine concentration in thyroid gland by blocking its transportation

A

Perchlorate
Thiocyanate
Pertechnetate

29
Q

what are some more anti thyroid drugs that can provoke autoimmune or destructive inflammatory thyroiditis hence leading to hypothyroidism

A

Amiodarone
Interleukin 2
Interferon alpha
Lithium

30
Q

what is Grave’s disease

A

Ab that binds to TSH receptor and stimulates the release of thyroid hormones

31
Q

only medical therapy that produces permanent reduction in thyroid activity

A

131-I