Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

NAPLEX 2024 > 45. Thyroid Disorders > Flashcards

45. Thyroid Disorders Flashcards

1
Q

2 thyroid hormones produced by the thyroid gland are ___ and ___

A

Triiodothyronine (T3)
Thyroxine (T4)

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

The thyroid gland is the only organ that can absorb ___, which is required for the production of both thyroid hormones

A

Iodine

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

T/F: T4 is primarily formed from the breakdown of T3

A

False - T3 is primarily formed from the breakdown of T4

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

Compare T3 and T4 in terms of potency and half-life

A

T3 is more potent than T4 but has shorter half-life

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

Thyroid hormone production is regulated by ___

A

Thyroid-stimulating hormone (TSH), aka thyrotropin

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

TSH is secreted by the ___

A

Pituitary gland (located in brain and regulates growth and development)

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

Drugs and Conditions that can cause hypothyroidism (hint: mneumonic)

A

Remember: I TALC
Interferons
Tyrosine kinase inhibitors (e.g. sunitinib)
Amiodarone
Lithium
Carbamazepine
Conditions: Hashimoto’s Disease

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

Explain negative feedback loop in the setting of T4 and TSH

A

When the level of free T4 increases, it inhibits secretion of TSH. Less TSH = decrease in T4 production

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

Hypothyroidism is a deficiency in ___ and elevation in ___

A

Deficiency in T4
Elevation in TSH

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

What is the most common cause of hypothyroidism?

A

Hashimoto’s disease - autoimmune condition that attacks thyroid gland

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

___ is an uncommon but potential fatal complication of hypothyroidism that can occur when hypothyroidism is left untreated for a long time or when hypothyroidism decompensates. It is a life-threatening emergency.

A

Myxedema coma

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

Initial treatment for myxedema coma is ___

A

IV levothyroxine

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

S/sx of hypothyroidism

A

Cold intolerance/sensitivity
Dry skin
fatigue
muscle cramps
voice changes
constipation
weight gain
goiter (possible; can be d/t low iodine intake)
Myalgias
weakness
depression
bradycardia
coarse hair or loss of hair
Menorrhagia (heavier than normal menstrual periods)
Memory and mental impairment

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

Dx of hypothyroidism

A

Low free T4 (normal range 0.9-2.3)
High TSH (normal range 0.3-3)

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

___ is the primary test to monitor thyroid function in those receive thyroid hormone replacement with drug treatment

A

TSH

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

In hypothyroidism pts, TSH level and symptoms should be monitored every ___ until levels are normal, then ___ later, and then yearly

A

4-6 weeks
4-6 months

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

What is the concern of thyroid hormone replacement use in elderly patients?

A

Too high of thyroid hormone replacement dose in elderly pts can cause Afib and fractures - monitor thyroid function as they age

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

What is the drug of choice for hypothyroidism?

A

Levothyroxine (T4)

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

T/F: When refilling levothyroxine, there is no difference between different manufacturers

A

Consistent preparation (i.e. same formulation and manufacturer) is preferred to minimize variability from refill to refill, not all generic formulations are A-rated (check Orange book)

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

Levothyroxine Full replacement dose

A

1.6 mcg/kg/day (IBW)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Levothyroxine starting dose if known CAD

A

12.5-25mcg

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

Who is indicated for full replacement dose vs partial replacement dose?

A

Full replacement = otherwise healthy, young (<50yo) pts with markedly increase TSH
Partial = milder hypothyroidism and those with comorbidities
Elderly pts often need 20-25% less per kg; may require <1mcg/kg/day

23
Q

Contraindications for hypothyroidism treatment

A

uncorrected adrenal insufficiency

24
Q

Warnings for hypothyroidism treatment

A

Decrease dose in CV disease (chronic hypothyroidism predisposes in CAD)
Decreased BMD (osteoporosis risk)

25
Q

Levothyroxine PO administration notes

A

Take with water at same time each day for consistent absorption
at least 60 min before breakfast or at bed time (at least 3 hrs after last meal)

26
Q

Levothyroxine IV to PO ratio

A

0.75:1

27
Q

Which hypothyroidism treatment option may be a concern for patients avoiding porcine (pork) products?

A

Thyroid desiccated USP (T3 and T4) (Armour Thyroid) - natural porcine-derived thyroid that contains both T3 and T4

28
Q

Levothyroxine tablet colors (hint: mneumonic)

A

Orangutans Will Vomit On You Right Before They Become Large, Proud Giants

25mcg - orange
50mcg - white (no dye)
75mcg - violet
88mcg - olive
100mcg - yellow
112mcg - rose
125mcg - brown
137mcg - turquoise
150mcg - blue
175mcg - lilac
200mcg - pink
300mcg - green

29
Q

What drugs decrease levothyroxine absorption?

A

Antacids (iron, calcium, aluminum, mg, multivitamins, cholestyramine, sevelamer, sucralfate, orlistat) - separate by 4 hrs

Others: Veltassa (separate by 3 hrs), lanthanum (separate by 2hrs)

30
Q

What drugs decrease thyroid hormone levels?

A

Estrogen, SSRIs, hepatic inducers

31
Q

What drugs decrease the effectiveness of levothyroxine by decreasing the conversion of T4 to T3?

A

Beta-blockers, amiodarone, PTU, and systemic steroids

32
Q

T/F: thyroid hormone is highly protein bound >99%

A

True

33
Q

Hyperthyroidism (also called overactive thyroid or ____) occurs when there is over-production of thyroid hormones

A

thyrotoxicosis

34
Q

Dx hyperthyroidism

A

FT4 high
TSH low

35
Q

S/sx of hyperthyroidism

A

Heat intolerance or increased sweating
weight loss
agitation, nervousness, irritability, anxiety
palpitations and tachycardia
fatigue and muscle weakness
frequent bowel movements and diarrhea
insomnia
tremor
thinning hair
goiter (possible)
Exophthalmos (protrusion of eyeballs), diplopia
Light or absent menstrual periods

36
Q

The most common cause of hyperthyroidism is ____

A

Graves’ disease (autoimmune disorder, antibodies stimulate thyroid to produce too much T4)

37
Q

Drug-induced causes of hyperthyroidism include ____

A

iodine (from diet or exposure to radiographic contrast media), amiodarone, and interferons

38
Q

Hyperthyroidism treatment

A

Medications, destroying part of the gland via radioactive iodine (RAI-131) or surgery

39
Q

What is typically used as symptom control for hyperthyroidism?

A

Beta-blockers (to reduce palpitations, tremors, and tachycardia)
PTU or methimazole can be used as temporary measure until surgery is complete

40
Q

It takes ____ of treatment with antithyroid meds at high doses to control hyperthyroidism symptoms

A

1-3 months
Note: dose should be reduced to prevent hypothyroidism once symptoms are controlled

41
Q

MOA thionamides (PTU, methimazole)

A

Inhibit synthesis of thyroid hormones by blocking oxidation of iodine in the thyroid gland
PTU also inhibits peripheral conversion of T4 to T3

42
Q

Boxed warnings for PTU

A

Severe liver injury and acute liver failure
Pregnancy - PTU is preferred in 1st trimester (d/t increase risk of fetal abnormalities with methimazole)

43
Q

Warnings for thionamides

A

Hepatotoxicity, agranulocytosis, DILE, vasculitis

44
Q

Side effects for thionamides

A

GI upset
Other: HA, rash, fever, constipation, loss of taste, lymphadenopathy, bleeding

45
Q

Of thionamides (PTU, methimazole (Tapazole)), which is drug of choice

A

Methimazole (d/t lower risk of liver damage) except PTU is preferred in thyroid storm and 1st trimester

Methimazole is preferred in 2nd and 3rd trimesters

46
Q

MOA iodides

A

Temporarily inhibit secretion of thyroid hormones; T4 and T3 levels will be reduced for several weeks but effect will not be maintained

47
Q

Examples of iodides used in hyperthyroidism

A

potassium iodide and iodine solution (Lugol’s solution)
Saturated solution of potassium iodide (SSKI, ThyroSafe)

48
Q

Why is potassium iodide used after exposure to radiation?

A

Blocks the accumulation of radioactive iodide, preventing thyroid cancer

49
Q

What is a thyroid storm

A

Life-threatening medical emergency characterized by decompensated hyperthyroidism that can be precipitated by infection ,trauma, surgery, radioactive iodine treatment, and non-adherence to antithyroid meds

50
Q

S/Sx of thyroid storm

A

Fever (>103ºF)
Tachycardia
Tachypenia
Dehydration
Profuse sweating
Agitation
Delirium
Psychosis
Coma

51
Q

Thyroid storm treatment regimen

A

Antithyroid (PTU preferred) + iodide therapy (SSKI or Lugol’s soution) + beta-blocker (propranolol) + systemic steroid (dexamethasone) + aggressive cooling with APAP and cooling blankets and other supportive treatments (e.g. antiarrhythmics, insulin, fluids, electrolytes)

52
Q

Treatment options for hypothyroidism in pregnancy

A

Levothyroxine is safe and recommended - will require 30-50% increase in dose

53
Q

Treatment options for hyperthyroidism in pregnancy

A

First trimester = PTU
Rest of pregnancy = methimazole

NAPLEX 2024 (74 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions