Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Endocrine > Thyroid > Flashcards

Thyroid Flashcards

(76 cards)

Start Studying
1
Q

The alpha subunit of TSH is identical to that of ___, ____, ____

A

LH, FSH, hCG

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What action does TSH have at the thyroid

A

stimulates iodine uptake
thyroid hormone production and release
upregulate TPO

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What substances can inhibit thyroid hormone production?

A

glucocorticoids, somatostatin, dopamine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe embryonic development and migration of the thyroid gland

A

HPT axis develops by 11 weeks
thyroid starts to function by 18 weeks
migrates via thyroglossal duct from base of tongue to neck

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

The thyroid gland takes up iodide via ______ under TSH stimulation

A

Na/I symporter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Iodine is ______ and then incorporated into thyroglobulin tyrosyl residues by TPO

A

oxidized/organified

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the Jod-Basedow phenomenon

A

in setting of longstanding iodine deficiency, patients exposed to high doses of iodine become hyperthyroid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the Wolff- Chaikoff effect

A

in setting of longstanding high levels of iodine, organification is transiently blocked to protect from hyperthyroidism
decrease in iodine transport allows for escape and normal thyroid hormone synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Under what conditions is TBG increased

A

hyperestrogenic states- pregnancy, estrogen therapy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Under what conditions is TBG decreased

A

steroids, glucocorticoids, protein malnutrition, cirrhosis, nephrotic syndrome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the action of 5’MDIs

A

conversion of T4 to T3 in peripheral tissue
an upregulation of thyroid activity
stimulated by TSH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the action of 5- MDIs

A

removes inner iodine, converting T4 to rT3 (inactive)

a downregulation of thyroid activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Thyroid hormone is critical for neurogenesis and _______ in the brain

A

myelination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the effect of thyroid hormone on carbohydrate metabolism?

A

Stimulates glucose absorption, increases gluconeogenesis and glycogenolysis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the effect of thyroid hormone on lipid metabolism?

A

Increases hepatic LDL cholesterol receptors, increases lipolysis
stimulates metabolism of cholesterol to bile acids- hypercholesterolemia in hypothyroid state

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the effect of thyroid hormone on cardiac function?

A

stimulates cardiac contractility, increases O2 consumption, enhanced sensitivity of tissue to catecholamines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the effect of thyroid hormone on bone turnover?

A

stimulates both bone formation and resorption, but resorption prevails in hyperthyroid state

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the effect of thyroid hormone on the gut?

A

stimulates gut motility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What lab findings are expected in central hypothyroidism

A
  • low T4

- TSH is low or inappropriately normal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What lab findings are expected in primary hypothyroidism

A
  • elevated TSH
  • normal or low T4
  • normal or low T3; remains normal until late in course of hypothyroidism
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What lab findings are expected in hyperthyroidism/ thyrotoxicosis

A

low TSH

normal or high T3/ T4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What lab findings are expected in central hyperthyroidism

A

high T3/T4

TSH is high or inappropriately normal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

TSI is the causative agent in _______

A

Graves disease

bind TSH receptor, mimic action of TSH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Anti-TPO is the causative agent in __________

A

Hashimoto’s thyroiditis

antibody against enzyme that oxidizes and organifies iodide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
List symptoms of hyperthyroidism
 Nervousness, agitation, irritability  Palpitations, tachycardia, atrial fibrillation, exertional dyspnea  Heat intolerance, increased perspiration, dehydration  Tremor  Weight loss or gain  Hyperdefecation  Muscle weakness, fatigue  Menstrual disturbance and infertility  Insomnia  Orbitopathy and dermopathy (seen exclusively in Graves’ disease)  Lid lag, stare
26
List causes of high uptake thyrotoxicosis
Graves disease toxic multinodular and solitary hyperfunctioning nodules TSH secreting pituitary adenoma selective pituitary thyroid hormone resistance
27
What antibodies are characteristic of Graves disease
TSI
28
What are the most common extra-thyroid manifestations of Graves disease
orbitopathy- diplopia, eye irritation, proptosis associated with smoking dermopathy- less common
29
Toxic multinodular and solitary hyperfunctioning nodules are more common in _____ patients
older vs Graves, more common in younger
30
Why does hyperemesis gravidum present as high uptake thyrotoxicosis
cross reactivity of hCG at TSH receptor
31
What are causes of low uptake thyrotoxicosis
``` subacute thyroiditis silent thyroiditis post partum thyroiditis struma ovarii factitious hyperthyroidism ```
32
Subacute thyroiditis is usually preceded by ______
upper respiratory infection
33
What symptom can distinguish subacute vs silent thyroiditis
thyroid gland tenderness in subacute but not silent
34
What is the mechanism of increased thyroid hormone in subacute thyroiditis
increased release (but NOT production) of thyroid hormone
35
What is the prognosis of subacute thyroiditis
self-limited condition may pass through hypothyroid phase prior to recovery treat symptomatically
36
______ thyroiditis may have an autoimmune component, usually resolves completely, and the thyroid gland is not tender
post-partum
37
What is struma ovarii
ovarian tumor with thyroidal elements that autonomously produce thyroid hormone
38
What drugs are used to treat hyperthyroidism
PTU | Methimazole
39
What is the mechanism of action of PTU/ methimazole
Inhibit iodination of tyrosyl groups in thyroglobulin and coupling to form T3 and T4.
40
Why is there delay in onset of action of PTU/ methimazole?
no effect on stored thyroglobulin- must deplete thyroglobulin stores before peripheral thyroid hormone levels begin to decline
41
Why does PTU act faster than methimaxole
additional activity of inhibiting conversion of T4 to T3 peripherally
42
What therapy is appropriate for treatment of hyperthyroidism in pregnancy?
PTU is the treatment of choice in the first trimester During the remainder of pregnancy (and at all other times), methimazole is felt to be safer due to the lower risk of hepatoxicity
43
What are adverse effects of PTU and methimazole
agranulocytosis hepatic toxicity urticaria, rash vasculitis, arthralgias
44
What is used to ablate thyroid in Graves, thyroid cancer?
radioactive I-131
45
What are signs of thyroid storm?
thyrotoxicosis, fever, mental status changes
46
How is thyroid storm treated?
PTU, beta blocker, glucocorticoids (block T4--> T3)
47
What antibodies are characteristic of Hashimoto's thyroiditis?
anti-TPO
48
What is the drug of choice for hormone replacement in hypothyroidism?
levothyroxine- consistent potency, long duration
49
In what settings is liothyronine used?
myxedema coma- faster onset | impaired T4--> T3 conversion due to 5' deiodinase defect
50
How is TSH used to evaluate the effectiveness of a thyroid hormone replacement dose?
High TSH = dose is too low. Low TSH = dose is too high.
51
What is myxedema coma?
Defined as severe hypothyroidism associated with mental status changes and hypothermia. Can have associated respiratory failure, hypotension, bradycardia, and hyponatremia
52
How is myxedema coma treated?
levothyroxine, possibly liothyronine, glucocorticoids, supportive care
53
TSH may be _____ during the recovery phase from illness, but usually returns to normal within a few months
elevated- not indicative of hypothyroidism
54
What are some medical reasons for decreased conversion of T4 to T3
caloric restriction major systemic illness drugs- PTU, glucocorticoids, propranolol, amiodarone
55
In illness, rT3 is increased due to _____ 5'MDI activity
decreased
56
Give a differential diagnosis for thyroid nodules
``` Adenoma (functioning or nonfunctioning) Cysts (simple, complex) Colloid nodules Developmental abnormalities Granulomatous disease Abscess Carcinoma ```
57
What features make malignancy more likely in a patient presenting with a thyroid nodule
Age 60 Positive family history, especially for medullary CA or MEN2 Rapid enlargement of the nodule Hoarseness, dysphagia History of head/neck irradiation, especially for papillary CA A cold nodule in the setting of Graves’ disease Firm or hard or fixed nodule Cervical lymphadenopathy Vocal cord paralysis
58
Describe workup of a thyroid nodule
- if TSH is normal or high- do FNA | - if TSH is low, do radionuclide imaging
59
FNA cannot distinguish between ______ and ______
follicular adenoma and follicular carcinoma- need to see tissue architecture to distinguish between these two
60
What type of thyroid cancer is suspected if: - complex branching papillae with fibrovascular cores associated wiht folicles - cells are cuboidal, nuclei are overlapping - nuclear clearing (orphan annie eye cells) - longitudinal nuclear grooves - psammoma bodies
papillary thyroid cancer
61
Metastases in papillary thyroid cancer occur via:
lymphatics
62
How is papillary thyroid cancer treated?
thyroidectomy +/- radio ablation
63
What gene mutations are associated with papillary thyroid cancer?
RET, BRAF, NTRK
64
What is the prognosis for papillary thyroid cancer
excellent
65
What type of thyroid cancer is suspected if: - follicular differentiation - invasion of adjacent thyroid parenchyma - capsule forms
follicular
66
Follicular thyroid cancer secretes _____
thyroglobulin- used as a tumor marker
67
Follicular thyroid cancer metastasizes:
hematogenously
68
How is follicular thyroid cancer diagnosed?
cannot dx by FNA, need a full tissue specimen to assess architecture, invasion of capsule
69
What type of thyroid cancer is suspected if: - firm rapidly growing mass - de-differentiated cells that do not secrete thyroglobulin - spindle or squamoid cells - cells are pleiomorphic
anaplastic
70
What mutation is associated with anaplastic cancer
BRAF
71
_______ is a malignancy of the C cells of they thyroid gland
medulary
72
What type of thyroid cancer is suspected if: - polygonal, plasmacystoid, or spindle cells - cells have granular cytoplasm and uniform round nuclei - amyloid deposits
medullary
73
Medullary cancers secrete _____
calcitonin
74
List the features of MEN1
Parathyroid hyperplasia Pancreatic islet cell tumors (gastrin, insulin, glucagon, somatostatin, VIP, pancreatic polypeptide) Pituitary adenoma chromosome 11; MENIN gene, loss of tumor suppression
75
List the features of MEN2a
Parathyroid hyperplasia Thyroid - medullary carcinoma of the thyroid (defining feature of MEN2) Adrenal - pheochromocytoma chromosome 10, RET oncogene activation in MEN 2a and 2b
76
List the features of MEN2b
``` Medullary CA of the thyroid Pheochromocytoma NOT parathyroid Marfanoid habitus Mucosal neuromas - usually present before other manifestations arise. ```

Endocrine (19 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions