Hyperthyroidism, Hypothyroidism and Thyroiditis Flashcards

1
Q

What is secondary thyroid disease?

A

Hypothalmic or pituitary disease

(this will indirectly impact the thyroid)

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2
Q

What is a goitre?

A

A swelling in the neck from an enlarged thyroid

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3
Q

By what other name is thyrotropin known?

A

Thyroid stimulating hormone

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4
Q

Which cells secrete TSH?

A

Thyrotroph cells

(anterior pituitary)

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5
Q

How are T3/T4 produced?

A
  1. Postive stimulus on hypothalamus
  2. Thyroid releasing hormone secreted
  3. TRH acts on anterior pituitary
  4. Thyroid stimulating hormone secreted
  5. TSH acts on thyroid
  6. T3/T4 produced
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6
Q

At which pointsin the hypothalmic-pituitary-thyroid axis can T3/T4 self regulate their release?

A
  1. Act on hypothalamus to reduce TRH release
  2. Act on pituitary to reduce TSH release
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7
Q

What are the thyroid hormone levels like in primary hypothyroidism?

A

Free T3/4 low

TSH high

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8
Q

What are the thyroid hormone levels like in primary hyperthyroidism?

A

Free T3/4 high

TSH low

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9
Q

What are the thyroid hormone levels like in secondary hypothyroidism?

A

Free T3/4 low

TSH low (or “normal” within the context)

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10
Q

What are the thyroid hormone levels like in secondary hyperthyroidism?

A

Free T3/4 high

TSH high (or “normal” in the context)

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11
Q

Hypothyroidism is the product of any disorder that results in what?

A

Insufficient thyroid hormone secretion

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12
Q

What is myxoedema?

A

Severe hypothyroidism

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13
Q

Pretibial myxoedema is a rare clinical sign of which condition?

A

Graves’ disease

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14
Q

Hypothyroidism is most common in which ethnic background?

A

White caucasian

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15
Q

Chronic thyroiditis is known by which other term?

A

Hashimoto’s thyroiditis

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16
Q

What can cause chronic goitrous thyroiditis (Hashimoto’s)?

A
  1. Iodine deficiency
  2. Drugs (amiodarone, lithium)
  3. Maternal transmission (antithyroid drugs)
  4. Hereditary biosynthetic defects
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17
Q

Non-goitrous primary hypothyroidism is known by which other term?

A

Atrophic thyroiditis

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18
Q

What may induce non-goitrous primary hypothyroidism?

A
  1. Post-ablative therapy (radioiodine, surgery)
  2. Post-radiotherapy (e.g. lymphoma treatment)
  3. Congenital developmental defect
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19
Q

Self-limiting primary hypothyroidism may be the result of which 3 main things?

A
  1. Withdrawal of antithyroid drugs
  2. Subacute thyroiditis with transient hypothyroidism
  3. Post-partum thyroiditis (immediately following birth)
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20
Q

What are some causes of secondary hypothyroidism?

A
  1. Infection
  2. Infiltrative
  3. Malignant
  4. Traumatic
  5. Congenital
  6. Cranial radiopathy
  7. Drug-induced
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21
Q

What is the most common cause of autoimmune hypothyroidism in the western world?

A

Hashimoto’s thyroiditis

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22
Q

How is autoimmune (Hashimoto’s) thyroiditis characterised?

A
  1. Antibodies against thyroid peroxidase (TPO)
  2. T cell infiltrate and inflammation
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23
Q

Which parts of the body are affected in hypothyroidism?

A
  1. Hair and skin
  2. Neurological
  3. Cardio
  4. Respiratory
  5. GI
  6. Gynae/reproductive
  7. Metabolic
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24
Q

How are the hair and skin affected in hypothyroidism?

A
  1. Coarse, sparse hair
  2. Dull expressionless face
  3. Periorbital puffiness
  4. Pale cool skin that feels doughy
  5. Vitiligo
  6. Hypercarotenaemia
  7. Pitting oedema
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25
Q

How is the cardiovascular system impacted by hypothyroidism?

A
  1. Reduced heart rate
  2. Cardiac dilatation
  3. Pericardial effusion
  4. Worsening heart failure
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26
Q

How are metabolic processes affected in hypothyroidism?

A
  1. Hyperlipidaemia
  2. Slowed, decreased appetite, weight gain
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27
Q

How is the GI system affected in hypothyroidism?

A
  1. Constipation
  2. Megacolon and intestinal obstruction
  3. Ascities
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28
Q

How is the respiratory system affected in hypothyroidism?

A
  1. Deep hoarse voice
  2. Macroglossia
  3. Obstructive sleep apnoea
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29
Q

What is macroglossia?

A

Abnormally enlarged tongue

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30
Q

How is the CNS affected in hypothyroidism?

A
  1. Decreased intellectual or motor activities
  2. Depression, psychosis
  3. Muscle stiffness, cramps
  4. Peripheral neuropathy
  5. Prolongation of the tendon jerks
  6. Carpal tunnel syndrome
  7. Cerebellar ataxia, encephalopathy
  8. Decreased visual acuity
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31
Q

How is the gynae/reproductive system affected in hypothyroidism?

A
  1. Menorrhagia (heavy periods)
  2. Oligo (reduced periods) or amenorrhoea (absent periods)
  3. Hyperprolactinaemia (due to increased TRH)
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32
Q

What may the results show for the following things in hypothyroidism?

a) Red cell size
b) Creatine kinase
c) LDL
d) Na+
e) Prolactin

A

a) Macrocytosis (enlarged)
b) Increased CK
c) Increased LDL
d) Decreased Na+ (hyponatraemia)
e) Increased prolactin (hyperprolactinaemia)

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33
Q

What are the three thyroid antibodies which ca be detected in Hashimoto’s thyroiditis (and Grave’s disease)?

A
  1. Anti-thyroid peroxidase (anti-TPO)
  2. Anti-thyroglobulin
  3. TSH receptor antibody
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34
Q

What may occur to a patient with hypothyroidism if restoration of metabolic rate occurs rapidly?

A

Cardiac arrhythmias

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35
Q

What is the treatment for both old and young patients with hypothyroidism?

A

Levothyroxine

50-100 micrograms (young)

25-50 micrograms (old)

Adjust every 4 weeks based on response

36
Q

Once TSH is stabilised in a hypothyroidism case, how often should it be checked?

A

Every 12-18 months

37
Q

In secondary hypothyroidism, what should the ;evothyroxine dose be titrated to?

A

Free T4 levels

(these are more reliable as there is decreased TSH production)

38
Q

Levothyroxine is essentially just ___

A

T4

39
Q

Why do dose requirements for levothyroxine (to treat hypothyroidism) increase during pregnancy?

A

There is increased thyroxine binding globulin

(less T3/4)

40
Q

A myxoedema coma typically affects which agen and sex?

A

Elderly women

41
Q

What are the findings on ECG for a myxoedema coma?

A
  1. Bradycardia
  2. Low voltage complexes
  3. Varying degrees of heart block
  4. T wave inversion
  5. Prolongation of QT interval
42
Q

Co-existing _________ failure is present in 10% of patients with a myxoedema coma

A

Co-existing adrenal failure is present in 10% of patients with a myxoedema coma

43
Q

Why is thyrotoxicosis?

A

Clinical, physiological and biochemical state arising when tissues are exposed to excess thyroid hormone

44
Q

Which areas of the body are affected by thyrotoxicosis?

A
  1. Hair and skin
  2. CNS
  3. Vision
  4. Cardiac
  5. Reproductive
  6. Muscles
  7. Metabolism
45
Q

How does thyrotoxicosis affect the cardiovascular system?

A
  1. Palpitation and AF
  2. Cardiac failure (rare)
46
Q

How does thyrotoxicosis affect the CNS?

A
  1. Anxiety
  2. Nervousness
  3. Irritability
  4. Sleep disturbance
47
Q

How does thyrotoxicosis affect the GI system?

A

Frequent loose bowel movements

48
Q

How does thyrotoxicosis affect the vision?

A
  1. Lid retraction
  2. Diplopia
  3. Proptosis (bulging of eye(s))
49
Q

How does thyrotoxicosis affect the hair and skin?

A
  1. Brittle thin hair
  2. Rapid fingernail growth
50
Q

How does thyrotoxicosis affect the reproductive system?

A

Menstrual changes - lighter and less frequent periods

51
Q

How does thyrotoxicosis affect the muscles?

A

Weakness - especially thighs and upper arms

52
Q

What are two broad causes of thyrotoxicosis associated with hyperthyroidism?

A
  1. Excessive thyroid stimulation
  2. Thyroid nodules with autonomous function
53
Q

Excessive thyroid stimulation may be brought about by what?

A
  1. Graves’ disease
  2. Hashitoxicosis
  3. Thyrotropinoma
  4. Thyroid cancer
  5. Choriocarcinoma (trophoblast tumour secreting hCG)
54
Q

What are the three broad causes of thyrotoxicosis not associated with hyperthyroidism?

A
  1. Thyroiditis
  2. Exogenous thyroid hormones
  3. Ectopic thyroid tissue
55
Q

What 3 things may induce thyrotoxicosis, thyroiditis, but not hyperthyroidism?

A
  1. De Quervain’s thyroiditis
  2. Post-partum thyroiditis
  3. Drug induced thyroiditis
56
Q

Is smoking related to higher incidence of Grave’s disease?

A

Yes

57
Q

In Grave’s disease, how are the following impacted?

a) TSH
b) Free T3/4

A

a) Decreased TSH
b) Increased free T3/4

58
Q

Which other abnormalities besides TSH and fT3/4 can be notoed on a blood test for an individual with Grave’s disease?

A
  1. Hypercalcaemia
  2. Raised ALP
  3. Leucopenia
  4. TSH receptor antibody
59
Q

Graves’ disease is associated with ___________ rates of osteoporosis

A

Graves’ disease is associated with increased rates of osteoporosis

60
Q

Which sign, classical of Graves’ disease is seen in the picture?

A

Pretibial myxoedema

61
Q

What is thyroid acropachy and which condition is it associated?

A

Soft tissue swelling of digits and finger clubbing

Graves’ disease

62
Q

Which clinical sign associated with the thyroid is specific to Graves’ disease?

A

Thyroid bruit

63
Q

How can thyroid eye disease (Grave’s eye disease) be treated?

A

Mild - lubricants

Severe - steroids, radiotherapy, surgery

64
Q

How does the thyroid differ in feel in patients with nodular thyroid disease versus Grave’s?

A

It may feel nodular

(it is smooth in Graves’)

65
Q

Nodular thyroid disease results in __________ fT3/4 and a ____________ TSH

A

Nodular thyroid disease results in raised fT3/4 and a decreased TSH

66
Q

Nodular thyroid disease is antibody ___________

A

Nodular thyroid disease is antibody negative

67
Q

What is a thyroid storm?

A

Severe hyperthyroidism

68
Q

What clinical signs suggest a thyroid storm?

A
  1. Respiratory and cardiac failure
  2. Hyperthermia
  3. Exaggerated reflexes
  4. Post infection or recent thyroid surgery
69
Q

What are the treatments for a thyroid storm?

A
  1. Lugol’s iodine
  2. Glucocorticoids
  3. Propylthiouracil
  4. Beta blockers
  5. Fluids
70
Q

What is the mechanism for antithyroid drugs?

A

Inhibition of thyroid peroxidase hence blocking thyroid hormone synthesis

71
Q

What is the first line antithyroid drug?

A

Carbimazole

72
Q

When would propyllthiouracil be used instead of carbimazole?

A

Pregnancy

(carbimazole has the risk of aplasia cutis)

73
Q

In which two ways can antithyroid drugs be administered?

A
  1. Dose titration
  2. Block and replace
74
Q

What are the main side effects of the antithyroid drugs?

A
  1. Rash, urticaria, arthralgia
  2. Cholestatic jaundice (hepatic failure (PTU))
  3. Agranulocytosis
75
Q

What is agranulocytosis?

A

Severe leukopenia

Usually involving neutrophils causing a neutropenia in the circulating blood

76
Q

What is the mechanism for beta blockers in the treatment of hyperthyroidism?

A

B-adrenoceptor blockade resulting in reduced sympathetic activity

77
Q

What is the beta blocker of choice in the treatment of hyperthyroidism?

A

Propranolol

78
Q

In which patients with hyperthyroidism may propranolol be unsuitable and what is the alternative?

A

Asthmatics (can induce bronchospasm)

CCBs instead e.g. diltiazem

79
Q

What is the first line treatment for relapsed Graves’ disease and nodular thyroid disease?

A

Radioiodine

80
Q

What are the main pitfalls in using radioiodine as treatment?

A
  1. Cannot be used in pregancy
  2. Contact precautions when on treatment e.g. away from children/pregnant women
  3. Increased risk of hypothyroidism
  4. May be contraindicated in active eye disease
81
Q

When may a thyroidectomy be useful?

A

Radioiodine is contraindicated

82
Q

What are the main surgical/anaesthetic risks of a thyroidectomy?

A
  1. Recurrent laryngeal nerve palsy
  2. Hypothyroidism
  3. Hypoparathyroidism
83
Q

Which drugs may induce thyroiditis?

A
  1. Amiodarone
  2. Lithium
84
Q

What is the normal range for TSH?

A

0.4-4.0mU/L

85
Q

What is the normal range for free T4?

A

9.8-18.8pmol/l