Brainscape's Knowledge GenomeTM

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


See full index

M2 Endo/Repro > Adult Thyroid - Javorsky > Flashcards

Adult Thyroid - Javorsky Flashcards

1
Q

What is the most common cause of primary hyperthyroidism?

What are some other causes?

A

Grave’s Disease

Toxic multinodular goiter, solitary follicular adenoma, and “thyroiditis”

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

Describe the epidemiology of Grave’s disease.

How does it arise?

A

More common in females, with a strong familial disposition.

Defect in suppressor T-cells allows T>B sensitization against a thyroid antigen. The produced antibodies stimulate the thyroid, increasing thyroid hormone release despite low TSH.

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

What ocular findings are seen in Grave’s disease? Why?

How is this assessed, and what is the major sequela?

A

Proptosis/exophthalmos, mostly due to inflammation of the extraorbital muscles (shares a common antigen with the thyroid).

Measure with a Hertel exophthalmometer. Increased extraocular pressure may damage optic nerve!

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

What are some typical signs and symptoms of thyrotoxicosis?

A

Alertness, emotional lability, poor concentration.

Muscular weakness and fatiguability (especially proximal), with fine tremor.

Heart palpitations, tachycardia.

Weight loss despite increased appetite. More bowel movements.

Lid lag & stare, with proptosis and periorbital edema.

Fine, moist skin (especially pretibial thickening)

Cold intolerance.

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

Following clinical suspicion of primary hyperthyroidism, what test should be ordered?

What will point to Grave’s disease in particular?

A

TSH levels; these should be low while T3/T4 are high or within reference.

Presence of TSIs (thyroid stimulating immunoglobulins).

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

What test can distinguish a grave’s disease from a multinodular goiter or follicular adenoma?

A

Radioiodine uptake scan. Pattern is diffuse and bilateral in Grave’s, solitary or irregular on the others.

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

Describe the mechanism of action of methimazole.

What are its indications?

Side effects?

A

Blocks oxidation (& organification) of iodine in the thyroid.

Used for hyperthyroidism in general.

Mild lupus-like symptoms, chance of reversible agranulocytosis.

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

Contrast propylthiouracil to methimazole in terms of mechanism of action, indication, and side effects.

A

Same mechanism with the addition of blocking T4 to T3 deiodination.

Both used for hyperthyroidism; methimazole is preferred in general but PTU for 1st trimester pregnancies.

Same side effects as methimazole, plus risk of hepatic failure.

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

How does iodide treat hyperthyroidism?

What else is it used for?

Side effects?

A

Iodide directly inhibits thyroid hormone release. It also “shrinks” hyperplastic glands.

Also used pre-op for thyroidectomy and for radioactive iodine fallout.

Acute sensitivity (angioedema / laryngeal edema / serum sickness), head cold.

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

What radioactive treatment is recommended for most thyroid carcinomas?

Which can it not treat?

A

131I, given as a single capsule.

Does not treat medullary thyroid carcinomas since they don’t take up iodine (these are made of parafollicular C cells!)

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

Mild thyrotoxicoses can be treated with treatments other than methimazole/PTU/iodide. Name 3 such treatments.

A

Beta-blockers (block adrenergic effects of thyroid hormones)

Lugol’s solution (oral iodine)

Cholestyramine (binds thyroid hormones in enterohepatic circulation)

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

What can cause a secondary hyperthyroidism?

How common is this?

Lab findings?

A

Pituitary adenoma of the thyrotrophs.

Not common at all.

Elevated TSH despite increased T3/T4.

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

Most thyroid neoplasias can be treated with surgical removal. What are the risks associated with this procedure?

A

Damage to the laryngeal nerves and to the parathyroid glands.

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

Say a patient presents with some weight loss, sweating, and mild heat intolerance. Her TSH is low, and thyroid scans are normal.

What is your diagnosis and treatment?

A

This is hyperthyroidism resulting from inflammatory destruction of the thyroid gland (“thyroiditis”), treat with only beta blockers and supportive care.

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

Name the drug that fits the description.

  1. Can be used pre-operatively for thyroidectomy.
  2. Used in first trimester pregnancies.
  3. Blocks organification of iodine.
  4. May cause angioedema, serum sickness, or just a head cold.
  5. Ablates the thyroid from within colloids.
A
  1. Iodide
  2. PTU.
  3. Methimazole and PTU.
  4. Iodide
  5. 131I
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is deficient in:

  • Primary hypothyroidism?
  • Secondary?
  • Tertiary?
A
  • Primary = Thyroid gland
  • Secondary = Pituitart gland
  • Tertiary = Hypothalamus
17
Q

What is the other name for Hashimoto’s Thyroiditis?

What is the pathogenesis of the disease?

What risk factors are thought to contribute to its development?

A

Chronic Lymphocytic Thyroiditis

Autoimmune destruction of the thyroid gland via cytokine release and inflammation following autoimmuine lymphocyte sensitization and activation

Risk factors:

  • Environmental factors
    • Viral or bacterial infection
    • High iodine intake
  • Genetic factors
    • e.g. Treg defects, etc.
18
Q

Antibodies against what thyroidal antigens can be seen in Hashimoto’s Thyroiditis?

A
  • Thyroglobulin
  • Thyroid peroxidase
  • TSH receptor
19
Q

Aside from Hashimoto’s, what are some other causes of primary hypothyroidism?

A
  • Partial or total thyroidectomy [duh]
  • Reversible autoimmune thyroiditis
    • silent and postpartum thyroiditis
  • Irradiation
  • Infiltrative & infectious disease
  • Thyroid dysgenesis
  • Iodine deficiency
  • Iodine excess (Wolff-Chaikoff effect)
  • Drugs
    • Antithyroid agents
    • Lithium
20
Q

What is the Wolff-Chaikoff effect?

How is this concept applicable therapeutically?

(not discussed in class materials, but the concept is simple and seems high yield down the road…)

A
  • Autoregulatory reaction of thyroid in response to a large iodine ingestion
  • **Decrease **in iodine organification and thyroid hormone production & release
  • Eventual downregulation of Na+-I- symporter (NIS) on thyroid follicular cell
  • Prevents excessive thyroid hormone formation following high iodine intake
  • Therapeutic uses of this principle:
    • Iodine was used to treat hyperthyroidism before newer agents
      • Including Grave’s (Grave’s thyroid esp. sensitive to this effect)
    • The basis of giving iodine to those exposed to nuclear fallout
      • Prevent thyroid uptake of damaging radioactive iodine

(All from Wiki)

21
Q

Name some causes of secondary or tertiary hypothyroidism

A
  • Tumors
  • Trauma
  • Infiltrative diseases
    • Sarcoidosis
    • Hemochromatosis
  • Drugs
    • Dopamine
    • Glucocorticoids
  • Inactivating mutations of genes in the hormonal axis
22
Q

Hypothyroidism has a boatload of potential symptoms. Name as many as you can.

[Memorizing all is likely low-yield]

A
  • Hair loss
  • Periorbital puffiness
  • Ptosis
  • Loss of outer third of eyebrow
  • Macroglosia
  • Hoarseness
  • Lack of facial expression
  • Depression
  • Fatigue
  • Pallor
  • Weight gain
  • Constipation + decreased bowel sounds
  • Bradycardia
  • Hypoventilation
  • Menstrual irregularities
  • Infertility
  • Pain & cramps
  • Cold intolerance, Hypothermia
  • Nonpitting edema
  • Cool, rough, dry skin
  • Peripheral neuropathy
23
Q

How can TSH be within the reference range in some instances of secondary/tertiary hypothyroidism?

A
  • Again, recall the principal that TSH may be in the reference range, but it is innappropirately not elevated given the low free T3 & T4.
  • Recall the reference range is technically only applicable to patients who are healthy!
24
Q

What two drugs are used to treat hypothyroidism?

Which is more commonly used?

A
  • Levothyroxine (recombinant T4) - most commonly used
  • Liothyronine (recombinant T3)

(Quick mnemonic: Levo = 4 letters = T4. Lio = 3 letters = T3.)

25
Q

Compare levothyroxineandliothyronine in terms of:

  • Relative potency
  • Oral bioavailability
  • Elimination half-life
  • Daily doses
A
26
Q
  1. What is severe hypothyroisism referred to as?
  2. Why can it be life-threatening?
  3. What is the typical clinical case?
A
  1. Myxedema coma
  2. Concerns:
    • Multiorgan dysfunction
    • Profound hypothermia
    • Hypoventilation
    • Hypotension
    • CNS symptoms
  3. An elderly patient with a history of hypothyroidism developed myxedema coma after a stressful precipitating event, e.g. infection, MI, or stroke.
27
Q
  1. What is the first test typically ordered when thyroid disease is expected: TSH or T4?
  2. Why is it not the other one?
A
  1. TSH is done first
  2. T4 and TSH share a log-linear relationship: a small change in T4 will result in a large change in TSH via the strength of the feedback. Thus, abnormalities in TSH levels are typically more easily detected.
28
Q
  1. What is the goal TSH range for patients taking levothyroxine?
  2. How long does it take a patient beginning levothyroxine therapy to reach steady-state levels?
  3. How much is a typical dose of levothyroxine once steady state is reached?
A
  1. 0.5 - 4 mU/L
  2. ~5-6 half-lives. T4 t1/2 = 7 days. So about 5-6 weeks.
  3. 1-2ug/kd/day
29
Q

What are the side effects of taking levothyroxine?

A

When monitored well and kept within physiologic levels:

NO reported side effects

M2 Endo/Repro (57 decks)

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