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Clin Med- Endo > Thyroid Disorders Lecture > Flashcards

Thyroid Disorders Lecture Flashcards

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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
This drug initially causes an increase in T4 (**hyperthyroidism**) but then resistance of T4 develops (**hypothyroidism**)
Amiodarone
26
Causes: * *Autoimmune** (Hashimoto's Thyroiditis) * *Iatrogenic** (post radioactive iodine tx) * *Congenital** (1/4000 newborns) * *Drug induced** (Amiodarone) * *Secondary forms** (hypothalamic or pituitary dz)
Hypothyroidism
27
Symptoms vary in severity Goiter often present 4/1000 women, 1/1000 men annually ## Footnote **lymphocytic infiltration of gland early presentation may be hyerthyroidism (release of stored hormone), BUT END RESULT IS HYPOTHYROIDISM**
Autoimmune hypothyroidism (ie Hashimoto's Thyroiditis)
28
TPO and Tg antibodies present, often high titers Diffusely enlarged, firm, finely nodular thyroid
Autoimmune hypothyroidism
29
Fatigue, lethargy Weakness, arthralgias Cold intolerance Constipation Dry skin, hair loss Headaches Menorrhagia **early or late symptoms of HYPOthyroidism?**
Early
30
Slow speech Altered mentation Muscle cramps Hoarse voice Weight gain Amenorrhea **Early or late symptoms of HYPOthyroidism?**
Late
31
Thin, brittle nails Thin, dry hair Delayed reflexes ..early or late sign of hypothyroidism
Early
32
Goiter Facial/eyelid puffiness Alopecia Bradycardia Myxedema (non pitting edema) Pleural/pericardial effusion ..early or late signs of hypothyroidism?
Late
33
Clinical syndrome associated with excessive levels of thyroid hormone
Thyrotoxicosis
34
MC cause of **hyper**thyroidism
Grave's disease
35
Causes: Toxic/"hot" adenomas/nodules Early Hashimotos or subacute thyroiditis Factitious- excessive thyroid hormone intake TSH secreting adenoma Amiodarone
Hyperthyroidism
36
Does **amiodarone** cause hyper or hypo thyroidism?
can cause both
37
**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
Graves disease
38
Hyperactivity, irritability, restlessness, anxiety Sweating, heat intolerance Palpitations Fatigue, weakness Decreased appetite, weight loss Diarrhea Decreased libido, oligomenorrhea
Symptoms of Graves disease (**hyperthyroidism**)
39
Tachycardia Arrhythmias Fine tremor Goiter/bruit Warm/moist skin Oily, fine hair Proximal muscle weakness **Opthalmopathy** **Dermopathy** Hyperreflexia
Signs of Graves dz (**hyperthyroidism**)
40
Opthalmopathy and dermopathy are unique to...
Graves disease
41
proptosis/exophthalmos, "lid lag" occurs because of **lymphocytic infiltration of orbit, muscles, eyelids** \*may cause diplopia and compression of optic nerve
Opthalmopathy in **graves disease**
42
Occurs in 3% Non inflammatory induration and plaque formation of pre-tibial areas leading to edema, thickened skin and "orange skinned" apperance (myxedema)
Dermopathy in **graves disease**
43
**Cardiac arrhythmias** (STs, PACs, PVCs, new A fib) **High output cardiac failure** **Thyroid storm and crises:** extreme thyrotoxicosis with delerium, high fever, dehydration, death
Complications of Graves/hyperthyroidism
44
``` Tx: Refer to endocrinology! Propranolol Thiourea drugs (ie Methimazole) ```
Tx for Graves/hyperthyroidism
45
**Methimazole** works by inhibiting thyroid peroxidase and blocking organification of...
iodine! (used in tx of graves dz/hyperthyroid)
46
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**
Thiourea drugs
47
First line thiourea drug for hyperthyroidism?
Methimazole (if pregnant or cant tolerate, use PTU)
48
Definitive therapy for hyperthyroidism ## Footnote **tx of choice for Graves dz!!**
Radioactive iodine (I-131) \*but not during pregnancy!
49
What will a pt develop within 1 year of radioactive iodine tx?
HYPOthyroidism ## Footnote **will need thyroid replacement for life**
50
Opthalmopathy may WORSEN after tx, especially in....
smokers **can tx with prednisone, 2/3 will improve with prednisone**
51
Is thyroid surgery the first line treatment for Graves?
No..not anymore \*only used now in kids and pregnant women with graves
52
If a pt with Graves failed radioactive iodine treatment..now what?
Can remove thyroid gland (but preserve parathyroid glands)
53
Do cardiac, ocular and psych problems always go away with treatment of Graves?
NO
54
If single..usually benign adenoma or colloid cyst
Thyroid nodule (can be cancer even if single tho, must do fine needle aspiration)
55
How do you rule out thyroid cancer if you feel a nodule?
Fine needle aspiration
56
Tx of nodules
Can tx with radioactive iodine (some nodules may hypersecrete thyroid hormone so you want to tx)
57
3x more common in women Well differentiated, slow growing **76% papillary 16% follicular** at risk if prior history of head/heck radiation
Thyroid cancer
58
Dx: fine needle aspiration, ultrasound Tx: thyroidectomy with preservation of parathyroid glands
Thyroid cancer
59
MC thyroid disease in the US 6x more common in females. can be familial **thyroid is diffusely enlarged with firm, small nodules**
Hashimoto thyroiditis
60
MC type of thyroid cancer
Papillary (least aggressive and spreads by local extension)
61
Diffuse uptake of radioactive iodine Graves Dz or Toxic nodule?
Graves! **toxic nodule has high uptake by nodule, none by rest of gland**
62
TPO and Tg antibodies
Hashimoto's thyroiditis (autoimmune hypothyroidism)
63
TSH-R Ab (TSAb)- IgG antibodies
Graves Dz

Clin Med- Endo (7 decks)

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