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MQW U5 > Pharm - Thyroid > Flashcards

Pharm - Thyroid Flashcards

1
Q

[Men/Women] are more likely to suffer from a thyroid condition

A

Women – 5-8x more likely

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2
Q

[Younger/Older] are more likely to suffer from hypothyroidism

A

Older – 17% of women by age 60 have hypothyroid conditions

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3
Q

What is the active metabolite form of thyroid hormone?

A

T3

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4
Q

What is the pro-hormone form of thyroid hormone?

A

T4 – Thyroxine

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5
Q

Where are the 3 deiodinases (D1, D2, D3) expressed?

A 
D1 = liver, kidney
D2 = CNS, pituitary, thyroid, heart, brown fat, skele muscle
D3 = brain, skin, placenta, tissue in disease states (tumors)
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6
Q

Which deiodinase has inactivating function?

A

D3 – inactivates T3 by converting to T2 and reverse T3

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7
Q

Which deiodinase contributes the most to circulating T3?

A

D2 – contributes ~60% of T3 converted from T4

—-D1 only contributes ~ 24%

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8
Q

What happens in Hashimoto’s Thyroiditis?

A

Autoantibodies against symporter affecting iodide transport

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9
Q

High TSH, Low T4

What thyroid state?

A

Primary Hypothyroidism – No feedback inhibition of TSH production

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10
Q

Low TSH, Low T4

What thyroid state?

A

Secondary Hypothyroidism – low TSH made in anterior pituitary is primary cause, leading to no T4 made in thyroid

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11
Q

Low TSH, High T4

What thyroid state?

A

Hyperthyroidism – Thyroid uses up normally made amounts of TSH to make lots of T4

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12
Q

Associated w/ [hyper/hypo] thyroidism:

  • -Goiter
  • -Cold Sensitivity
  • -Heat Intolerance
  • -Exopthalmos
  • -Excessive sweating
  • -Tachycardia
  • -Constipation
  • -Weight gain
  • -Dry/brittle hair
A
  • -Goiter = HypO
  • -Cold Sensitivity = HypO
  • -Heat Intolerance = HypER
  • -Exopthalmos = HypER
  • -Excessive sweating = HypER
  • -Tachycardia = HypER
  • -Constipation = HypO
  • -Weight gain = HypO
  • -Dry/brittle hair = HypO
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13
Q

How is most circulating T3 generated?

A

Peripheral conversion from T4 (80%) – 20% is direct secretion

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14
Q

Adult onset (especially older women) severe form of hypothyroidism is called ___

A

Myxedema

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15
Q

Infant/childhood hypothyroidism that causes mental retardation and Dwarfism is called ___

A

Cretinism

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16
Q

The first synthetic thyroid hormone is called ___ and is specifically the ___ form.

A

Levothyroxine Sodium – T4 replacement

17
Q

T3 form synthetic thyroid hormone is called ___

A

Liothyronine Sodium

18
Q

Synthetic thyroid hormone that is a mixture of T3/T4 called ___ has more ___ form by weight.

A

Liotrix —4:1 ratio of T4:T3

19
Q

Patients with what condition have difficulty converting T4 to T3?

A

Chronic Fatigue Syndrome

20
Q

In what patient population should Levothyroxine be initiated with lower doses?

A

Patients w/ Angina Pectoris

21
Q

Half life and time to peak theraputic effect of Levothyroxine?

A

Half life = 6-7days
Time to Peak theraputic = 3-4weeks
Longer half life compared to Liothyronine

22
Q

Half life and time to peak theraputic effect of Liothyronine?

A

Circulating half life = 1day

Reaches peak levels in 2-4hr after oral administration

23
Q

How do you treat acute emergency hypothyroid conditions (like Myxedema Coma)?

A

IV formulation of Liothyronine

24
Q

[Levothyroxine/Liothyronine] is more potent by weight

A

T3 Liothyronine is 4x more potent on mcg for mcg basis

25
Q 
Heart palpitations
Nervousness
Heat intolerance
Excessive sweating
Insomnia
Tremors
Frequent bowel movments
Excessive weightloss
Are all symptoms of what?
A

Thyroid hormone overdose – similar to hyperthyroidism symptoms

26
Q

What is the most common preventable cause of mental handicap in the world?

A

Iodine deficiency –> goiter (hypothyroidism)

27
Q

What area is referred to as the “goiter belt”?

A

Great Lakes and Northwestern region of US

28
Q

What are 3 common causes of primary and secondary hypothyroidism?

A

Primary: Hashimoto’s, Iodine Deficiency, Thyroid Ablation

Secondary: Pituitary adenoma, pituitary surgery, radiotherapy

29
Q

What is the most common cause of hyperthyroidism and who does it most often affect?

A

Grave’s disease – autoimmune thyroid-stimulating antibodies activating thyrotropin receptor on thyroid cells

Most often affect women 20-40 y/o

30
Q

What are the 4 common causes of hyperthyroidism?

A
  1. Grave’s disease
  2. Nodular goiter –older age 90% of nodules are benign
  3. Thyroiditis – inflammation–> excess release
  4. Thyroid cancer
31
Q

Mechanism of action of antithyroid drugs?

A

Inhibit Thyroid Peroxidase activity – prevent organification of iodide and coupling of iodotyrosine

32
Q

Which antithyroid drug also reduces deiodination of T4 to T3 by inhibiting D1 deiodinase activity?

A

Propylthiouracil

33
Q

What are 3 severe side effects of antithyroid drugs (Methimazole, Propylthiouracil, Carbimazole)

A
  1. Agranulocytosis (granulocyte less than 500/mm3)
  2. Hepatitis
  3. Lupus-like syndrome

**These are absolute contraindications for further antithyroid drug therapy

34
Q

Propylthiouracil vs. Methimazole

  • -Longer half life
  • -Faster excretion
  • -Relatively less transplacental passage
  • -Higher Concentration in breast milk
  • -Higher Agranulocytosis risk
A
  • -Longer half life = Methimazole
  • -Faster excretion = Propylthiouracil
  • -Relatively less transplacental passage = Propylthiouracil
  • -Higher Concentration in breast milk = Methimazole
  • -Higher Agranulocytosis risk = Propylthiouracil
35
Q

Mechanism of action of Radioactive Iodine?

A

131 I = thyroid specific Iodine isotope destroys sufficient thyroid tissue to restore euthyroid

  • -Emits beta particles and gamma rays
  • -5 day half-life
36
Q

Indications and contraindications for radioactive Iodine therapy?

A

Indication: relapsed hyperthyroidism after antithyroid drug therapy

Contraindications: pregnancy, breast-feeding (passes to breast milk)

37
Q

Why are B-blockers used for hyperthyroid therapy?

A

Control symptoms – tremor, anxiety, palpitations

MQW U5 (8 decks)

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