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Clin Med- Endo > Thyroid Disorders Lecture > Flashcards

Thyroid Disorders Lecture Flashcards

1
Q

TSH turns thyroid ON/OFF by binding to receptors on…

A

Follicular cells

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2
Q

Essential for making thyroid hormones

need 0.2 mg daily dietary intake

A

Iodine

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3
Q

MIT + DIT + TG = ?

A

T3 (Triiodothyronine)

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4
Q

DIT + DIT + TG =?

A

T4 (Thyroxine)

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5
Q

The thyroid makes 13x more of which thyroid hormone?

A

13x more T4 than T3

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6
Q

Which is more biologically active…T4 or T3?

A

T3

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7
Q

50% of released T4 is deiodinated for form..

A

T3

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8
Q

T4: only 0.025% free

T3: only 0.3% free

..what does this mean?

A

T3 is more biologically active!

only free hormone enters the cells and exhibits biologic activity

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9
Q

Only ______ (FREE or BOUND) hormone enters cells and exhibits biologic activity?

A

Free!

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10
Q

T4 conversion to T3 occurs in…

A

peripheral tissue

*especially liver, brain, heart

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11
Q

Deiodinase enzymes do what?

A

Convert T4 to T3 (in peripheral tissue)

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12
Q
  • *Made in liver**
  • *Binds 80% of thyroid hormone**; remainder binds to TBPA and albumin
A

Thyroxine Binding Globulin (TBG)

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13
Q

Will changes in TBG, which ultimately cause changes in T4 and T4, cause clinical disease?

A

NO!

ie..TBG increases with estrogen (OCPs and pregnancy)

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14
Q

Bind nuclear receptors in most tissues (brain, muscle, heart, kidneys, liver, pituitary)

Cell differentiation during development (cell growth, maturation, gene expression)

Help maintain thermogenic and metabolic homeostasis
Essential for normal metabolism, protein synthesis, organ function

A

Thyroid hormone actions

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15
Q

MC thyroid disorders are result of…

A

Autoimmune proesses

(over/under stimulate thyroid hormone)

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16
Q

Most informative lab tests when evaluating thyroid function?

A

TSH and T4

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17
Q

Extremely sensitive indicator of thyroid function

Secretion controlled via negative feedback from thyroid hormone

norm= 0.27-4.2

A

TSH

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18
Q

Asymptomatic patients with TSH levels 3-6 should be followed for development of…

A

Hypothyroidism

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19
Q

Does a normal TSH exclude hyper/hypo thyroidism?

A

Majority of time YES!

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20
Q

TSH is low
Free T4 is normal
Pt clinically seems to have hyperthyroidism

..what lab now?

A

T3!

(this is pretty much the only scenario you would check T3 levels)

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21
Q

Anti-thyroid antibodies are elevated in…

A

Hashimoto’s thyroiditis
Graves disease

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22
Q

TSH-R AB (TSAb)- thyroid stimulating hormone receptor antibodies (IgG) that stimulate….

A

gland activity

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23
Q

TSH-R AB (aka TSI, thyroid stimulating immunoglobulin) are elevated in 80% of these patients?

A

Grave’s disease

(these stimulate gland activity)

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24
Q

Definitive test for evaluating thyroid nodules

A

Fine needle aspiration

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25
Q

This drug initially causes an increase in T4 (hyperthyroidism) but then resistance of T4 develops (hypothyroidism)

A

Amiodarone

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26
Q

Causes:

  • *Autoimmune** (Hashimoto’s Thyroiditis)
  • *Iatrogenic** (post radioactive iodine tx)
  • *Congenital** (1/4000 newborns)
  • *Drug induced** (Amiodarone)
  • *Secondary forms** (hypothalamic or pituitary dz)
A

Hypothyroidism

27
Q

Symptoms vary in severity
Goiter often present
4/1000 women, 1/1000 men annually

lymphocytic infiltration of gland
early presentation may be hyerthyroidism (release of stored hormone), BUT END RESULT IS HYPOTHYROIDISM

A

Autoimmune hypothyroidism (ie Hashimoto’s Thyroiditis)

28
Q

TPO and Tg antibodies present, often high titers

Diffusely enlarged, firm, finely nodular thyroid

A

Autoimmune hypothyroidism

29
Q

Fatigue, lethargy
Weakness, arthralgias
Cold intolerance
Constipation
Dry skin, hair loss
Headaches
Menorrhagia

early or late symptoms of HYPOthyroidism?

A

Early

30
Q

Slow speech
Altered mentation
Muscle cramps
Hoarse voice
Weight gain
Amenorrhea

Early or late symptoms of HYPOthyroidism?

A

Late

31
Q

Thin, brittle nails
Thin, dry hair
Delayed reflexes

..early or late sign of hypothyroidism

A

Early

32
Q

Goiter
Facial/eyelid puffiness
Alopecia
Bradycardia
Myxedema (non pitting edema)
Pleural/pericardial effusion

..early or late signs of hypothyroidism?

A

Late

33
Q

Clinical syndrome associated with excessive levels of thyroid hormone

A

Thyrotoxicosis

34
Q

MC cause of hyperthyroidism

A

Grave’s disease

35
Q

Causes:

Toxic/”hot” adenomas/nodules
Early Hashimotos or subacute thyroiditis
Factitious- excessive thyroid hormone intake
TSH secreting adenoma
Amiodarone

A

Hyperthyroidism

36
Q

Does amiodarone cause hyper or hypo thyroidism?

A

can cause both

37
Q

Antibodies directed to TSH receptor

Over active gland, which leads to: hypersecretion, hypertrophy, hyperplasia

**Goiters common!

8x more common in women
onset 20-40 yo

A

Graves disease

38
Q

Hyperactivity, irritability, restlessness, anxiety
Sweating, heat intolerance
Palpitations
Fatigue, weakness
Decreased appetite, weight loss
Diarrhea
Decreased libido, oligomenorrhea

A

Symptoms of Graves disease (hyperthyroidism)

39
Q

Tachycardia
Arrhythmias
Fine tremor
Goiter/bruit
Warm/moist skin
Oily, fine hair
Proximal muscle weakness
Opthalmopathy
Dermopathy
Hyperreflexia

A

Signs of Graves dz (hyperthyroidism)

40
Q

Opthalmopathy and dermopathy are unique to…

A

Graves disease

41
Q

proptosis/exophthalmos, “lid lag” occurs because of lymphocytic infiltration of orbit, muscles, eyelids

*may cause diplopia and compression of optic nerve

A

Opthalmopathy in graves disease

42
Q

Occurs in 3%

Non inflammatory induration and plaque formation of pre-tibial areas leading to edema, thickened skin and “orange skinned” apperance (myxedema)

A

Dermopathy in graves disease

43
Q

Cardiac arrhythmias (STs, PACs, PVCs, new A fib)

High output cardiac failure

Thyroid storm and crises: extreme thyrotoxicosis with delerium, high fever, dehydration, death

A

Complications of Graves/hyperthyroidism

44
Q 
Tx: Refer to endocrinology!
Propranolol
Thiourea drugs (ie Methimazole)
A

Tx for Graves/hyperthyroidism

45
Q

Methimazole works by inhibiting thyroid peroxidase and blocking organification of…

A

iodine!

(used in tx of graves dz/hyperthyroid)

46
Q

Used to treat hyperthyroidism
SE of pruritus
Must monitor T4 levels
Tx for 12-18 months
recurrent thyrotoxicosis in 50% after drug D/C’d

A

Thiourea drugs

47
Q

First line thiourea drug for hyperthyroidism?

A

Methimazole

(if pregnant or cant tolerate, use PTU)

48
Q

Definitive therapy for hyperthyroidism

tx of choice for Graves dz!!

A

Radioactive iodine (I-131)

*but not during pregnancy!

49
Q

What will a pt develop within 1 year of radioactive iodine tx?

A

HYPOthyroidism

will need thyroid replacement for life

50
Q

Opthalmopathy may WORSEN after tx, especially in….

A

smokers

can tx with prednisone, 2/3 will improve with prednisone

51
Q

Is thyroid surgery the first line treatment for Graves?

A

No..not anymore

*only used now in kids and pregnant women with graves

52
Q

If a pt with Graves failed radioactive iodine treatment..now what?

A

Can remove thyroid gland (but preserve parathyroid glands)

53
Q

Do cardiac, ocular and psych problems always go away with treatment of Graves?

A

NO

54
Q

If single..usually benign adenoma or colloid cyst

A

Thyroid nodule

(can be cancer even if single tho, must do fine needle aspiration)

55
Q

How do you rule out thyroid cancer if you feel a nodule?

A

Fine needle aspiration

56
Q

Tx of nodules

A

Can tx with radioactive iodine

(some nodules may hypersecrete thyroid hormone so you want to tx)

57
Q

3x more common in women

Well differentiated, slow growing

76% papillary
16% follicular

at risk if prior history of head/heck radiation

A

Thyroid cancer

58
Q

Dx: fine needle aspiration, ultrasound

Tx: thyroidectomy with preservation of parathyroid glands

A

Thyroid cancer

59
Q

MC thyroid disease in the US

6x more common in females. can be familial

thyroid is diffusely enlarged with firm, small nodules

A

Hashimoto thyroiditis

60
Q

MC type of thyroid cancer

A

Papillary

(least aggressive and spreads by local extension)

61
Q

Diffuse uptake of radioactive iodine

Graves Dz or Toxic nodule?

A

Graves!

toxic nodule has high uptake by nodule, none by rest of gland

62
Q

TPO and Tg antibodies

A

Hashimoto’s thyroiditis (autoimmune hypothyroidism)

63
Q

TSH-R Ab (TSAb)- IgG antibodies

A

Graves Dz

Clin Med- Endo (7 decks)

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