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Y2 - Endocrine > Hyperthyroidism and Hypothyroidism > Flashcards

Hyperthyroidism and Hypothyroidism Flashcards

1
Q

What are the definitions of hyperthyroidism, hypothyroidism and thyroiditis?

A 
Hyperthyroidism = overactive thyroid
Hypothyroidism = underactive thyroid
Thyroiditis = inflammation of the thyroid caused by excess thyroid hormone
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2
Q

What is the difference between primary and secondary thyroid disease?

A

Primary - disease affecting the thyroid gland itself

Secondary - hypothalamic or pituitary disease affecting the thyroid

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3
Q

What are the thyroid hormones?

A

T3 (triiodothyronine)

T4 (thyroxine)

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4
Q

Is more of T3 or T4 secreted?

A

T4 (80%)

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5
Q

Describe the hypothalamic-pituitary-thyroid axis?

A

The hypothalamus secretes TRH (thyrotropin releasing hormone)
TRH stimulates the pituitary to secrete TSH (thyroid stimulating hormone), also called thyrotropin
TSH stimulates the thyroid to secrete T3 and T4
Excess T3 and T4 inhibit the pituitary gland and hypothalamus to stop secreting TSH and TRH

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6
Q

Which thyroid hormone needs to undergo an extra step, and what is that step?

A

T4 is converted to T3 which activates it

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7
Q

How are TSH levels affected in primary hyper and hypothyroidism, and why?

A

In primary hyperthyroidism the problem in the thyroid means too much T3 and T4 are secreted so the negative feedback effect means TSH levels are low
In primary hyperthyroidism the problem in the thyroid means not enough T3 and T4 are secreted so the negative feedback effect means TSH levels are high

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8
Q

What are the symptoms of thyrotoxicosis?

A 
Brittle, thin hair
Proptosis (bulging eyes)
Enlarged thyroid
Palpitations
Tremor of fingers
Soft nails
Sweating
Frequent, loose bowel movements
Infertility
Scant menstrual periods
Muscle weakness
Heat intolerance
Weight loss
Anxiety, nervousness, irritability
Insomnia
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9
Q

What are the causes of thyrotoxicosis?

A 
Graves' disease
Hashitoxicosis
Thyrotropinoma
Thyroid cancer
Toxic solitary thyroid nodule
Toxic multi nodular goitre
Thyroid inflammation (subacute, post-partum or drug-induced thyroiditis)
Over-treatment with levothyroxine
Metastatic thyroid carcinoma
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10
Q

Which causes of thyrotoxicosis are associated with hyperthyroidism?

A 
Grave's disease
Hashitoxicosis
Thyrotropinoma
Thyroid cancer
Toxic solitary thyroid nodule
Toxic multi nodular goitre
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11
Q

What percent of the population are affected by Graves’ disease?

A

Females - about 1%

Males - about 0.1%

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12
Q

What ages usually present with Graves’ disease?

A

20-50 year olds

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13
Q

What causes Graves’ disease?

A

Autoimmune - interacting susceptibility genes (70%) and environmental factors

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14
Q

What is the biggest risk factor for developing Graves’ disease?

A

Smoking

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15
Q

What are the results of blood tests done in Grave’s disease?

A 
TSH - low
Free T3/4 - high
Hyperhalcaemia
Increased alkaline phosphatase
Leucopenia
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16
Q

What conditions are associated with Graves’ disease?

A

Osteoporosis

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17
Q

What antibody test results indicate Graves’ disease?

A

TSH receptor antibody (70-100%)

Anti-TPO antibody (70-80%)

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18
Q

What clinical signs are specific to Graves’ disease?

A

Pretibial myxoedema
Thyroid acropachy (clubbing)
Thyroid bruit
Graves’ eye disease

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19
Q

What is nodular thyroid disease?

A

Hyperthyroidism with a nodular-feeling asymmetrical goitre

Occurs in older patients with a more insidious onset

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20
Q

What will blood test results be in nodular thyroid disease?

A

High free T4 and T3
Low TSH
Antibody negative
High uptake on scintigraphy

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21
Q

What investigation is diagnostic for nodular thyroid disease?

A

Thyroid ultrasound

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22
Q

What is thyroid storm (crisis)?

A

Severe hyperthyroidism involving respiratory and cardiac collapse, hypothermia, exaggerated reflexes - a medical emergency

23
Q

Which patients are most likely to have thyroid storm?

A

Hyperthyroid patients with an acute infection/illness or recent thyroid surgery

24
Q

What is the treatment for thyroid storm?

A

Lugol’s iodine
Glucosorticoids
Propylthiouracil
Beta blockers

25
Q

What is the first line treatment for hyperthyroidism?

A

Carbamizole

26
Q

What are the contraindications of carbamizole?

A

Not used in early pregnancy

27
Q

What is the second line treatment for hyperthyroidism, and when is it given?

A

Propylthiouracil

In the 1st trimester of pregnancy or young women who could get pregnant

28
Q

What is the mechanism of anti-thyroid drugs?

A

Inhibition of thyroid peroxidase, to block thyroid hormone synthesis

29
Q

What are the side effects of anti-thyroid drugs?

A

Allergic reeaction
homeostatic jaundice
Agranulocytosis

30
Q

What are the symptoms of agranulocytosis?

A

Fever
Oral ulcer
Oropharyngeal infection

31
Q

What is done if a patient exhibits symptoms of agranulocytosis?

A

Stop drugs immediately and urgent FBCcheck

ATDs cannot be used again

32
Q

When are beta blockers used in hyperthyroidism?

A

To manage symptoms of sympathetic activity like palpitations

33
Q

When are beta blockers not used, and what is used instead?

A

In asthmatic patients

CCBs used instead

34
Q

When is radioiodine used in hyperthyroidism?

A

1st choice for relapsed Graves’ disease and nodular thyroid disease

35
Q

When is radioiodine contraindicated?

A

Pregnancy

Thyroid eye disease (but can be used with steroid cover_

36
Q

What are the risks of thyroidectomy?

A

Recurrent laryngeal nerve palsy
Hypothyroidism
Hypoparathyroidism

37
Q

What are causes of thyroiditis?

A 
Hashimoto's thyroiditis
De Quervain's (viral)
Post-partum
Drug-induced
Radiation
Acute supportive thyroiditis
38
Q

What is subacute thyroiditis?

A

Usually self-limiting, may be triggered by a viral infection

May be associated with neck tenderness, fever or other viral symptoms

39
Q

What is subclinical thyroid disease?

A

Abnormal TSH with normal thyroid hormone levels
Can progress to overt thyroid disease
Treatment advised if borderline overt

40
Q

What is sick euthyroid syndrome?

A

The hypothalamic-pituitary-thyroid axis is affected by intercurrent illness

41
Q

What are the goitrous causes of primary hypothyroidism?

A 
Hashimoto's thyroiditis
Iodine deficiency
Drug-induced  (amiodarone, lithium)
Maternally transmitted (e.g. antithyroid drugs)
Hereditary biosynthetic defects
42
Q

What are the non-goitrous causes of primary hypothyroidism?

A

Atrophic thyroiditis
Post-ablative therapy
Post-radiotherapy
Congenital development defect

43
Q

What is the most common cause of hypothyroidism?

A

Hashimoto’s thyroiditis

44
Q

What is Hashimoto’s thyroiditis?

A

Autoimmune destruction of the thyroid gland and reduced hormone production

45
Q

What investigative signs are characteristic of Hashimoto’s thyroiditis?

A

Antibodies against thyroid peroxidase (TPO)

T-cell infiltrate and inflammation microscopically

46
Q

What are the clinical features of Hashimoto’s thyroiditis?

A 
Coarse, sparse hair
Puffy face
Vitiligo
Cold intolerance
Pitting oedema
Reduced heart rate
Decreased appetite
Weight gain
Constipation
Hoarse voice
Obstructive sleep apnoea
Depression
Muscle stiffness
Peripheral neuropathy
Carpal tunnel syndrome
Heavy periods
47
Q

What will the results of blood tests be in Hashimoto’s thyroiditis?

A 
High TSH
Low free T3/4
High MCV
High creative kinase
High LDL cholesterol
48
Q

What antibodies are positive in Hashimoto’s thyroiditis?

A

Anti-TPO antibody

Anti-thyroglobin antibody

49
Q

What is the management for Hashimoto’s thyroiditis?

A

Levothyroxine

50
Q

What are the contraindications for levothyroxine, and what effects do they have?

A

PPIs
Iron tablets
Calcium tablets
Impair absorption so levothyroxine doesn’t work

51
Q

What is myxoedema coma?

A

An extreme case of hypothyroidism that can involve bradycardia, heart block and type 2 respiratory failure

52
Q

Which patients are typically affected by myxoedema coma?

A

Elderly women with long-standing but frequently unrecognised or untreated hypothyroidism

53
Q

What is the treatment for myxoedema coma?

A

Cardiac monitoring for arrhythmias
Broad spectrum antibiotics
Thyroxine - give cautiously and add hydrocortisone if any indication of adrenal failure

Y2 - Endocrine (9 decks)

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