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Med 3: Thyroid Disease > Thyroid Disease > Flashcards

Thyroid Disease Flashcards

1
Q

What is another term for hyperthyroidism?

A

Thyrotoxicosis (high thyroid hormone levels, low TSH because pituitary gland senses you have enough thyroid hormone)

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2
Q

Give the main potential causes of hypothyroidism

A

. Primary hypothyroidism (90% cases caused by Hashimoto’s autoimmune thyroiditis)
. Secondary to hypothalamus/anterior pituitary defect
. Iatrogenic (drug-induced, radiotherapy/surgery, lithium)
. Lack of dietary iodine
. Thyroid hormone resistance

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3
Q

How would primary hypothyroidism affect the plasma concentrations of TSH and thyroid hormones? Would a goitre be present?

A

. Decrease in thyroid hormones (thyroid can’t produce much)
. Increase in TSH (anterior pituitary still working, but TSH can’t take effect so stays in blood)
. Goitre present (due to increased TSH over-stimulating thyroid gland)

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4
Q

How would secondary hypothyroidism affect the plasma concentrations of TSH and thyroid hormones? Would a goitre be present?

A

. Decrease in thyroid hormones
. Decrease in TSH (hypothalamus produces less TRH–> less TSH from ant pit, or just ant pit dodgy so produces less TSH)

. Goitre not present because less TSH

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5
Q

How would lack of dietary iodine, medical intervention, or thyroid hormone resistance affect the plasma concentrations of TSH and thyroid hormones?

A

. Decrease in thyroid hormones
. Increase in TSH (TSH still produced by functioning ant pit, but can’t have effect on dodgy thyroid)
. Goitre present (due to increased TSH over-stimulating thyroid gland)

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6
Q

Give the main potential causes of hyperthyroidism

A

. Graves’ disease (autoimmune attack on thyroid= hypersecretion)
. Secondary to excess TRH/TSH secretion by hypothalamus/anterior pituitary
. Hyper-secreting thyroid tumour
. Iatrogenic (medications, lithium)

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7
Q

What effect would Graves’ disease have on plasma levels of TSH and thyroid hormones? Would a goitre be present?

A

. Increase thyroid hormones, decrease TSH

. Goitre (even though decreased TSH, thyroid-stimulating antibodies over-stimulate thyroid gland)

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8
Q

What effect would secondary hyperthyroidism have on plasma levels of TSH and thyroid hormones? Would a goitre be present?

A

. Increase TSH, increase thyroid hormones

. Goitre

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9
Q

What effect would a tumour/iatrogenic causes of hyperthyroidism have on plasma levels of TSH and thyroid hormones? Would a goitre be present?

A

. Increase thyroid hormones, decrease TSH

. Goitre

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10
Q

Why is a goitre always present with hyperthyroidism?

A

Because thyroid gland is overstimulated with TSH of TSIs (thyroid stimulating immunoglobulins), so becomes enlarged

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11
Q

What is a goitre?

A

Enlargement of the thyroid gland

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12
Q

What is a diffuse goitre? What is it caused by?

A

Whole thyroid gland enlarged due to overstimulation by excess TSH/TSIs

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13
Q

What is a nodular goitre? What is it caused by?

A

Abnormal thyroid gland different from surroundings, often caused by tumour

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14
Q

What is myxoedema?

A 
Puffy appearance (face, hands, feet)
Skin thickened and dry
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15
Q

What is cretinism?

A

Dwarfism and mental retardation (can occur in neonates with hypothyroidism- all newborns tested for T4 and TSH)

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16
Q

What is the euthyroid state?

A

Normal thyroid state

17
Q

How do you test for hyper/hypothyroidism? What would the result be for primary and secondary hypothyroidism and hyperthyroidism?

A 
. Thyroid function test (check levels of T3/T4 and TSH)
. Primary hypo: Low T3/T4, high TSH
. Secondary hypo: Low T3/T4, low TSH
. Primary hyper: High T3/T4, high TSH
. Secondary hyper: High T3/T4, high TSH
18
Q

How do you test for Hashimoto’s?

A

. Test for thyroid antibodies (TPO, anti-thyroid antibodies)

19
Q

How do you manage hypothyroidism? How do you manage hyperthyroidism?

A

Hypothyroidism: Give synthetic thyroid hormones, Levo-thyroxine (T4) or Liothyronine (T3)

Hyperthyroidism: Anti-thyroid drugs, surgery, radiotherapy

20
Q

Why is levo-thyroxine the drug of choice for hypothyroidism?

A

. Body can convert synthetic T4 to active T3, so can regulate amount used by body
. Longer half life, so doesn’t matter if patient forgets to take it once
. Liothyronine (synthetic T3) is very biologically active and the rapid onset can induce heart failure

21
Q

When must levo-thyroxine be used with caution? How can associated complications be avoided?

A

. Thyroid hormones act synergistically on beta-adrenoceptors with catecholamines and sympathetic NS
. Could uncover/worsen angina (increase HR etc.)
. Give beta-blocker alongside levo-thyroxine if patient has angina (check baseline ECG with initial dosage)

22
Q

When is liothyronine used over levo-thyroxine?

A

Liothyronine is used when a rapid effect is required, e.g. in severe hypothyroid state

23
Q

What is the most common cause of hypothyroidism? What is the most common cause of hyperthyroidism?

A

Hypothyroidism- Hashimoto’s
Hyperthyroidism- Graves’
(Both autoimmune)

24
Q

What is exophthalmos? What is it a symptom of? What is it caused by and how is it treated?

A

. Bilateral protrusion of eyes, common symptom of Graves’ disease (as well as goitre)
. Lipid proteins deposited in back of eyes, or
lymphocytes infiltrate soft tissue of eyes–> pushes eyes forwards
. Eye drops to lubricate so eyelids can close
. Surgery to remove lipid deposits

25
Q

How would you test for Graves’ disease? How about a thyroid tumour?

A

. For Graves’, test for thyroid-stimulating antibodies

. For tumour, use iodine-123 to do thyroid uptake test

26
Q

Anti-thyroid drugs are often given to treat hyperthyroidism. Give an example of two anti-thyroid drugs available in the UK.

Which is the drug of choice?

A

. Thionamides: Carbimazole and propylthiouracil (PTU)

. Carbimazole usually drug of choice (unless adverse reaction, then use PTU)

27
Q

How does carbimazole work? What are the common side effects of carbimazole?

A

Inhibits TPO to inhibit iodination and coupling process (= decreased production of thyroid hormones)
Common side effects: rashes, pruritus, can have bone marrow suppression

28
Q

How does propylthiouracil work?

A

Inhibits TPO and blocks conversion of T4 to T3

29
Q

Why do patients with Graves’ disease often relapse after treatment?

A

They still have autoantibodies that attack the thyroid

30
Q

Why do anti-thyroid drugs take a few week to generate a response?

A

Colloid stores of thyroid hormones available in thyroid gland to continue using, and these have a long half-life

31
Q

How can symptoms of hyperthyroidism be relieved while anti-thyroid drugs (thionamides) are taking time to kick in?

A

. Use non-selective beta-blockers to reduce effect of catecholamines
. Rapid relief of tremor, palpitations, anxiety (within 4 days)

32
Q

Two approaches to drug regimens with anti-thyroid drugs are ‘dose titration’ and ‘block and replace’. What is the difference between these methods and which is more effective?

A

. Dose titration is when anti-thyroid drugs only are given
. Block and replace is when T4 replacement is given alongside anti-thyroid drugs
. Equally as effective, but dose titration associated with lower rate of side effects

33
Q

What is iodine-123 used for? What is iodine-131 used for?

A

. I-123 used to check if thyroid tumour present (uptake test)
. Radioactive I-131 used for radiotherapy to destroy thyroid tumours (beta-emissions kill cells)

34
Q

Why can radioactive iodine be used to target thyroid tumours specifically?

A

Thyroid gland uptakes iodine (to synthesise thyroid hormones with tyrosine)

35
Q

When is radioactive iodine-131 first-line treatment? How is it administered? What is a potential negative effect?

A

. For older patients with hyperthyroidism and nodular goitres, when hyperthyroidism recurs after trying anti-thyroid drugs
. Patient has single drink/capsule (maximum effect occurs 2-4 months after taking)
. Can result in hypothyroidism

Med 3: Thyroid Disease (2 decks)

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