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CARES > Thyroid Examination > Flashcards

Thyroid Examination Flashcards

1
Q

High vs low T3

A

High levels of circulating T3 significantly increases metabolism resulting in weight loss and potentiates the effects of catecholamines such as adrenaline resulting in excessive sympathetic output (e.g. tachycardia, tremor, anxiety).

Low levels of circulating T3 have the opposite effect, causing weight gain, low mood, constipation, poor memory and hyporeflexia.

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2
Q

How should the hands be inspected in thyroid examination?

A

Dry skin: associated with hypothyroidism.

Excessive sweating: associated with hyperthyroidism.

Thyroid acropachy: similar in appearance to finger clubbing but caused by periosteal phalangeal bone overgrowth secondary to Graves’ disease.

Onycholysis: painless detachment of the nail from the nail bed associated with hyperthyroidism.

Palmar erythema: reddening of the palms associated with hyperthyroidism, chronic liver disease and pregnancy.

Peripheral tremor is a feature of hyperthyroidism reflecting sympathetic nervous system overactivity.

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3
Q

How can peripheral tremor be examined?

A
  1. Ask the patient to stretch their arms out in front of them.
  2. Place a piece of paper across the back of the patient’s hands.
  3. Observe for evidence of a peripheral tremor (the paper will quiver).
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4
Q

Expected HR for thyroid problems?

A

Bradycardia (<60 bpm): has a wide range of aetiologies (e.g. healthy athletic individuals, hypothyroidism, atrioventricular block, medications)

Tachycardia (>100 bpm): has a wide range of aetiologies (e.g. hyperthyroidism, anxiety, hypovolaemia).

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5
Q

Expected heart rhythm?

A

An irregular rhythm is most commonly caused by atrial fibrillation which can be associated with hyperthyroidism.

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6
Q

How should the face be inspected in thyroid examination?

A

Dry skin: associated with hypothyroidism.

Excessive sweating: associated with hyperthyroidism.

Eyebrow loss: the absence of the outer third of the eyebrows is associated with hypothyroidism (although this is a rare sign).

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7
Q

How should the eyes be inspected in thyroid examination?

A
  1. Lid retraction
  2. Exophthalmos
  3. Eye inflammation
  4. Eye movements
  5. Lid lag
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8
Q

Expected results for eye investigations?

A

Inspect the eyes for evidence of eye pathology associated with thyrotoxicosis (e.g. Graves’ disease) including lid retraction, eye inflammation, exophthalmos (also known as proptosis), eye movement abnormalities and lid lag.

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9
Q

What is exophthalmos?

A

Exophthalmos is bulging of the eye anteriorly out of the orbit.

Bilateral exophthalmos develops in Graves’ disease, due to oedema and lymphocytic infiltration of orbital fat, connective tissue and extraocular muscles.

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10
Q

How should the thyroid be inspected in thyroid examination?

A

Inspect the midline of the neck from the front and the sides noting any masses (e.g. goitre) or scars (e.g. previous thyroidectomy). The normal thyroid gland should not be visible.

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11
Q

If a mass is identified when inspecting the thyroid, what further assessments should be done?

A
  1. Ask patient to swallow water

2. Ask patient to protrude tongue

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12
Q

Expected result of patient swallowing water?

A

Observe the movement of the mass:

  • Thyroid gland masses (e.g. a goitre) and thyroglossal cysts typically move upwards with swallowing.
  • Lymph nodes will typically move very little with swallowing.
  • An invasive thyroid malignancy may not move with swallowing if tethered to surrounding tissue.
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13
Q

Expected result of patient protruding their tongue?

A
  • Thyroglossal cysts will move upwards noticeably during tongue protrusion.
  • Thyroid gland masses and lymph nodes will not move during tongue protrusion.
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14
Q

How should the thyroid be palpated in thyroid examination?

A

Stand behind the patient and ask them to tilt their chin slightly downwards to relax the muscles of the neck to aid palpation of the thyroid gland.

  • Size?
  • Symmetry?
  • Masses?
  • Consistency?
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15
Q

How should the lymph nodesAssess for local lymphadenopathy which may indicate the metastatic spread of primary thyroid malignancy.

A

Assess for local lymphadenopathy which may indicate the metastatic spread of primary thyroid malignancy.

Position the patient sitting upright and examine from behind if possible

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16
Q

Order of events of thyroid examination?

A
  1. Introduction
  2. General inspection
  3. Hands
  4. Face
  5. Thyroid inspection
  6. Thyroid palpation
  7. Lymph node palpation
  8. Trachea (deviated?)
  9. Percussion of sternum
  10. Auscultation of thyroid gland
  11. Special tests
  12. Complete examination
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17
Q

Order of events of thyroid examination?

A
  1. Introduction
  2. General inspection
  3. Hands
  4. Face
  5. Thyroid inspection
  6. Thyroid palpation
  7. Lymph node palpation
  8. Trachea (deviated?)
  9. Percussion of sternum
  10. Auscultation of thyroid gland
  11. Special tests
  12. Complete examination
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18
Q

Thyroid hormonal axis overview?

A
  1. Hypothalamus releases TRH
  2. TRH stimulates anterior pituitary to release TSH
  3. TSH stimulates thyroid to release T4 and T3
  4. T4 inhibits the pituitary and hypothalamus in a negative feedback loop
19
Q

What does TFTs refer to?

A

Thyroid function tests

20
Q

What is included in TFTs?

A

TSH (0.4 – 4 mU/L)

Free T4 (9 – 25 pmol/L)

Free T3 (3.5 – 7.8 nmol/L)

N.B. There are separate reference ranges for children and pregnant women.

21
Q

Is fT3 or fT4 more relevant?

A

fT4: thyroid releases T4 and T3 at a ratio of about 20:1 respectively, with T3 mainly being produced by peripheral conversion of T4.

22
Q

Clinical features of hypothyroidism?

A
  • lethargy
  • weight gain
  • cold intolerance
  • constipation
  • hair loss
  • dry skin
  • depression
  • bradycardia
  • memory impairment
  • menorrhagia
23
Q

Clinical features of hyperthyroidism?

A
  • tachycardia
  • palpitations (AF)
  • hyperactivity
  • weight loss with increased appetite
  • sweating
  • heat intolerance
  • diarrhoea
  • fine tremor
  • hyper-reflexia
  • goitre
  • palmar erythema
  • onycholysis
  • muscle weakness and wasting
  • oligomenorrhea/amenorrhoea
24
Q

What is oligomenorrhea?

A

A condition in which you have infrequent menstrual periods. It occurs in women of childbearing age

25
Q

What is Grave’s disease?

A

Graves’ disease is an immune system disorder that results in the overproduction of thyroid hormones. Although a number of disorders may result in hyperthyroidism, Graves’ disease is a common cause.

(look at IMS)

26
Q

What occurs in Grave’s disease?

A

Your immune system attacks the thyroid and causes it to make more thyroid hormone than your body needs.

27
Q

Clinical features of Grave’s disease?

A
  • Exophthalmos/proptosis
  • Chemosis
  • Diffuse symmetrical goitre
  • Pretibial myxoedema (rare)
  • Other autoimmune conditions
  • Thyroid bruit
28
Q

What is 1ary hypothyroidism?

A

Primary hypothyroidism involves reduced secretion of thyroid hormone from the thyroid gland itself (most common cause of hypothyroidism)

29
Q

Pathophysiology of 1ary hypothyroidism?

A
  1. Less T4 and T3 are produced due to the thyroid’s reduced capacity to produce hormone or respond to TSH.
  2. As a result, there is reduced negative feedback on the pituitary and hypothalamus.
  3. The reduction in negative feedback results in increased production of TRH (which we don’t typically measure) and TSH.
  4. The end result is low T4 and T3 and a raised TSH.
30
Q

Typical findings of 1ary hypothyroidism?

A

Raised TSH: due to the absence of negative feedback.

Low T4: due to the thyroid’s inability to produce enough T4.

31
Q

Causes of 1ary hypothyroidism?

A
  • Autoimmune thyroiditis (50%)
  • Iodine deficiency or excess
  • Thyroidectomy
  • Therapy with radioactive iodine – a treatment for hyperthyroidism
  • External radiotherapy
  • Drugs
  • Thyroid agenesis or dysgenesis
32
Q

What is 2ary hypothyroidism?

A

A reduction in the hormones that stimulate the thyroid to produce T3/T4; pathology that affects pituitary (and hypothalamus)

Rarer (1% of cases)

33
Q

Pathophysiology of 2ary hypothyroidism?

A
  1. Decreased TRH or TSH results in decreased stimulation of thyroid gland
  2. Decreased T3 and T4 production
  3. The low T3 and T4 would normally stimulate the pituitary and hypothalamic glands to increase TRH and TSH production, however, they are unable to increase production.
  4. The end result is low T4 and T3 and a normal/low TSH.
34
Q

Typical findings of 2ary hypothyroidism?

A

Normal/low TSH: due to a lack of production.

Low T4: due to the absence of any positive feedback from TSH.

35
Q

Most common cause of 2ary hypothyroidism?

A

Pituitary adenoma

36
Q

What is 1ary hyperthyroidism?

A

Primary hyperthyroidism involves an excessive production of T3 and T4 by the thyroid gland itself

37
Q

Pathophysiology of 1ary hyperthyroidism?

A
  1. The thyroid produces excessive amounts of T4 and T3.
  2. The excessive T4 and T3 cause negative feedback on the pituitary and hypothalamus, resulting in decreased production of TRH and TSH.
  3. The end result is a raised T3 and T4 and a low TSH.
38
Q

Typical findings of 1ary hyperthyroidism?

A

Raised T3/T4: due to excessive production.

Low TSH: due to negative feedback on the pituitary/hypothalamus.

39
Q

Most common cause of 1ary hyperthyroidism?

A

Grave’s disease (75%)

40
Q

Other causes of 1ary hyperthyroidism?

A

Graves’ disease (75% of all cases)

Toxic multinodular goitre

Toxic adenoma

Iodine-induced (rare)

Trophoblastic tumour (very rare)

41
Q

What is 2ary hyperthyroidism?

A

Secondary hyperthyroidism involves stimulation of the thyroid gland by excessive thyroid-stimulating hormone (TSH).

42
Q

Pathophysiology of 2ary hyperthyroidism?

A
  1. TSH production is increased by either the pituitary/hypothalamus or another source
  2. The excess TSH causes overstimulation of the thyroid gland, resulting in high levels of T3 and T4 production.
  3. Normally a raised T3 and T4 level would cause negative feedback, decreasing TSH production, however, in this instance, the TSH production is not responsive to any negative feedback, resulting in continued excess production.
43
Q

Typical findings of 2ary hyperthyroidism?

A

Raised T3/T4: due to excess production that is driven by a raised TSH level.

Raised TSH: due to excess production.

44
Q

Causes of 2ary hyperthyroidism?

A

TSH-secreting tumour

Chorionic-gonadotropin secreting tumours (hCG secreting)

Thyroid hormone resistance (usually euthyroid): TSH is resistant to T3/T4 negative feedback.

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