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HRM Final Exam > Hellekant Thyroid > Flashcards

Hellekant Thyroid Flashcards

1
Q

What hormones decrease the release of TSH?

A

Somatostatin, dopamine, and high glucocorticoids

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2
Q

Where are receptors for TRH found? What kind of receptors are they?

A

Anterior pituitary; transmembrane Gq receptors

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3
Q

TSH is similar to what other hormones? Why?

A

Alpha chain of TSH is same as LH, FSH, placental hormone hCG

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4
Q

What chain is specific to TSH and confers specificity of hormonal action?

A

Beta chain

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5
Q

What cells have TSH receptor?

A

Thyroid follicular cells

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6
Q

What type of receptor is the TSH receptor?

A

Plasmamembrane receptor; GCPR

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7
Q

What dietary requirement is needed to synthesize thyroid hormones?

A

Iodide

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8
Q

How is iodide brought into the thyroid follicular cell?

A

Via active transport with Na+

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9
Q

After iodide is brought into the thyroid follicular cell, what happens next?

A

Iodide is transported to follicular lumen and undergoes oxidation to become iodine

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10
Q

What enzyme is responsible for oxidation of iodide in thyroid hormone synthesis?

A

Thyroid peroxidase

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11
Q

After oxidation to iodine, what is the next step in thyroid hormone synthesis? What enzyme is responsible for this?

A

Organification of iodine via thyroid peroxidase

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12
Q

After organification, what is the next step in thyroid hormone synthesis? What enzyme is responsible for this?

A

Coupling via thyroid peroxidase

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13
Q

What does thyroid peroxidase do?

A

Oxidation, organification, and coupling reactions

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14
Q

What enzyme is responsible for converting T4 to T3?

A

5-deiodinase

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15
Q

What thyroid hormone is more active? Has a shorter half life?

A

T3 is more active and has a shorter half life

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16
Q

What proteins bind thyroid hormones?

A

Thyroid binding globulin (t3=t4), transthyretin (T4>T3), albumin (T3>T4)

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17
Q

What increases the amount of thyroxine binding globulin?

A

Pregnancy or OCP use (estrogen)

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18
Q

What decreases thyroxine binding globulin?

A

Hepatic failure, steroid use

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19
Q

What is the function of deiodinase?

A

Converts T4 to T3

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20
Q

Where is deiodinase I found?

A

Prevalent in liver and kidney

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21
Q

What is the MOA of propylthiouracil?

A

Inhibits both thyroid peroxidase and 5-deiodinase

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22
Q

Where is deiodinase II found?

A

Brian, pituitary, skeletal and cardiac muscle

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23
Q

Where is deiodinase III found?

A

Brain, skin, placenta

24
Q

What is the function of deiodinase III?

A

Deactivates hormones

25
Q

What does TSH stimulate in the thyroid gland?

A

Secretion of mature thyroid hormones, increases thyroid peroxidase synthesis, thyroglobulin transcription, and Na/I transport activity

26
Q

What are the main functions of thyroid hormones?

A

Regulation of BMR, increased heat production, increased glucose utilizatin, uptake, and synthesis; increases HR and contractility

27
Q

What is Cretinism?

A

Congenital lack of thyroid hormone

28
Q

What are the symptoms of cretinism?

A

Profound mental retardation, short stature, delay in motor development, coarse hair, protuberant abdomens

29
Q

What are the signs of cretinism in newborns?

A

Resp difficulty, cyanosis, jaundice, horse cry, umbilical hernia, marked retardation of bone maturation

30
Q

What is the importance of assessing thyroid function at birth?

A

Early diagnosis can prevent permanent mental retardation; development can proceed normally

31
Q

What effect does thyroid hormones have on the sympathetic system?

A

Increases beta-1 receptors, resulting in increased HR and contractility

32
Q

What are the 4Bs of T3?

A

Brain maturation, bone growth, beta adrenergic effects, basal metabolic rate

33
Q

What effect does excess thyroid hormone have on bone?

A

Promote bone turnover, with net bone loss and hypercalciuria

34
Q

What effect does excess thyroid hormone have on cholesterol?

A

Increases in LDL receptor number, accelerating LDL clearance

35
Q

The thyroid-stimulating immunoglobulin test is used to diagnose what disease?

A

Graves

36
Q

What is a difference in release of TSH and T3/T4?

A

TSH has circadian rhythm, but T3/T4 do not

37
Q

Why does a goiter develop in iodine deficiency?

A

TSH stimulates Na/I transporter synthesis, thyroid peroxidase and thyroglobulin synthesis; this buildup can result in a mass

38
Q

Why does a goiter develop in Graves diseas?

A

Antibodies stimulate TSH receptor, resulting in lots of T3/T4 production

39
Q

What is levothyroxine?

A

T4

40
Q

What is liothyronine?

A

T3

41
Q

What drug can be used as T3 replacement?

A

Liothyronine

42
Q

What drug class is used for treatment of hyperthyroidism?

A

Thioamides

43
Q

What drugs are in the class thioamides?

A

Methimazole, carbimazole, propylthiouracil, potassium iodide

44
Q

What is used for thyroid ablation?

A

Iodine 131

45
Q

What radioactive iodine is used for thyroid imaging?

A

Iodide 123

46
Q

What decreases the absorption of levothyroxine?

A

Iron, calcium, AlOH, soy

47
Q

What drug is more potent, methimazole or PTU?

A

Methimazole is 10x more potent

48
Q

What is the MOA of propylthiouracil?

A

Inhibits thyroid peroxidase and inhibits deiodinase I

49
Q

What is the MOA of methimazole?

A

Inhibits thyroid peroxidase

50
Q

What are the uses for iodine in antithyroid therapy?

A

Thyroidectomy, to treat thyroid storm, and protection from radioactive iodine

51
Q

What is iodide 123 used for?

A

Thyroid scan

52
Q

What is Iodide 131 used for?

A

Destroy thyroid

53
Q

What is a major AE caused by propylthiouracil?

A

Hepatotoxicity

54
Q

What thioamide can cause ANCA associated antibodies?

A

PTU

55
Q

What thioamide is avoided in in 1st trimester?

A

Methimazole

56
Q

What is used to treat hyperthyroidism in 1st trimester of pregnancy?

A

PTU

57
Q

What teratogenic effects does methimazole have?

A

Aplasia cutis

HRM Final Exam (21 decks)

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