Hypo and Hyperthyroidism Flashcards

1
Q

What is hyperthyroidism

A

Due to excess T3 and T4

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2
Q

Is hyperthyroidism usually caused by excess TSH

A

No, this is very rare

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3
Q

What is the most common cause of hyperthyroidism

A

Graves’ disease

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4
Q

What is thyrotoxicosis

A

Clinical syndrome resulting from the effect on the tissues due to circulating T3 and T4 - increased metabolic rate

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5
Q

What three diseases usually result in hyperthyroidism

A
  1. Graves’ thyroiditis
  2. Functioning adenoma
  3. Toxic nodular goitre
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6
Q

What is strums ovarii

A

A rare tumour in which thyroid hormones are produced and released into the blood - leading to an excess

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7
Q

Signs of Graves’ thyroiditis

A
  1. Associated with diffuse goitre
  2. Thyroid is enlarged, firm and red
  3. Hyperplasia of acing epithelium
  4. Reduction in colloid
  5. Accumulation of lymphocytes in lymphoid follicle formation
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8
Q

Why does the thyroid appear red in Graves’ thyroiditis

A

Due to increased vascularisation

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9
Q

How does Graves’ thyroiditis occur

A

IgG are produced (autoimmune) which bind to thyroid epithelial cells and stimulates it like TSH would - stimulatory hypersensitivity

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10
Q

What are the IgG autoantibodies known as

A

LATS - Long-acting thyroid hypersensitivity

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11
Q

Symptoms of individuals with Graves’ thyroiditis

A
  1. Exopthalmos (bulging of eyes due to deposition of fat in retrobulbal area + inflammatio/oedema of extra-ocular muscles) - MOST COMMON
  2. Accumulation of mucopolysaccharides in dermis
  3. Finger clubbing
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12
Q

Do adipocytes have receptors to TSH

A

Yes

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13
Q

What is nodular goitre

A

Thyroid enlarges (usually due to iodine deficiency)

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14
Q

How does hypothyroidism effect the metabolic rate

A

Lowers it

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15
Q

Symptoms of hypothyroidism

A
  1. Accumulation of mucopolysaccharides in the face - myxoedema face
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16
Q

How does hypothyroidism effect a newborn

A
  1. Physical growth and mental development impaired - Cretinism
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17
Q

Where is cretinism common

A

Areas where diet contains insufficient iodine for thyroid hormone synthesis

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18
Q

What is the most common cause of hypothyroidism

A

Hashimoto’s thyroiditis

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19
Q

Describe some iatrogenic causes of hypothyroidism

A
  1. Removal of the thyroid surgically

2. Certain drugs causing it as a side-effect

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20
Q

What is myxoedema

A

swelling of the skin and underlying tissues giving a waxy consistency

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21
Q

What can happen to the thyroid later on in patients with hypothyroidism

A

Atrophy and fibrosis

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22
Q

Appearance of the thyroid during hypothyroidism

A
  1. Firm, fleshy and pale
  2. Densley infiltrated by plasma cells and lymphocytes with lymphocytic colloid formation
  3. reduction in colloids
  4. Thyroid epithelial cells enlarge and develop eosinophilic granular cytoplasm
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23
Q

Why do thyroid epithelial cells develop eosinophilic granular cytoplasms in hypothyroidism and what are they now known as

A

Due to proliferation of mitochondria

Askanazy cells

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24
Q

Why is there a transient phase at the beginning of Hashimoto’s thyroiditis

A
  1. Damage to the thyroid follicles lead to release of thyroglobulin into circulation
25
Q

What would appear in blood tests for patient’s who are positive for Hashimoto’s thyroiditis

A
  1. Two autoantibodies

One reacting with thyroid peroxidase

One reacting with thyroglobulin

26
Q

Where are the autoantibodies in Hashimoto’s thyroiditis formed

A

Locally by plasma cells infiltrating the thyroid

27
Q

Define goitre

A

Enlargemnt of the whole gland WITHOUT hyperthyroidism

28
Q

What is parenchyma’s goitre

A
  1. First hyperplasia of the thyroid epithelium
  2. Loss of coloids
  3. Eventually less active areas are compressed by hyperplastic areas
  4. Fibrosis may separate the less active areas - multi nodular goitre
29
Q

How can multi-nodular goitre be detected

A

They can be palpated clinically

30
Q

What is colloid goitre

A
  1. No epithelia hyperplasia (unlike parenchyma)
  2. Lots of colloid found
  3. Colloids form cysts
  4. Haemorrhage found
31
Q

Symptoms of colloid goitre

A
  1. Tracheal compression (difficulty breathing)

2. Stridor

32
Q

What is stridor

A

Harsh or greeting sound during breathing

33
Q

How is hypothyroidism caused (3 ways)

A
  1. Iodine deficiency
  2. Inherited enzyme defects in T3 n T4 synthesis
  3. Drugs that induce hypothyroidism
34
Q

Under a histological slide, what is an indication of colloid goitre

A

The follicles are distended by accumulated colloid

35
Q

How do we deal with people who come into a clinic with a solitary mass in the thyroid (this is very common)

A
  1. Checking thyroid secretory status (serum TSH, T3 and T4 levels)
  2. Ultrasound imaging and checking for thyroid neoplasia \
36
Q

What two ways do solitary masses tend to go

A
  1. Turn out to be one large nodule in a multi nodular goitre

2. May be neoplastic (rare)

37
Q

What is the most common thyroid tumour

A

Follicular adenoma

38
Q

Signs of follicular adenoma

A

1, Solid mass within a fibrous capsule, compressing the adjacent gland
2. Centre shows haemorrhage and cystic changes

39
Q

Histological signs of follicular adenoma

A
  1. Compact follicles lined by epithelium
  2. Nuclear hyperchromatism
  3. Very little colloid
  4. Fibrous capsule not breached by tumour
  5. Epithelial cells have large central clear areas in nuclei
40
Q

How common is a follicular carcinoma

A

Rare

41
Q

Why is a follicular carcinoma rare

A

Because tumours are well-differentiated

42
Q

What is follicular carcinoma associated with

A

Exposure to ration (x-rays)

43
Q

In what aged patients is papillary adenocarcinoma found

A

Less than 45s

44
Q

Appearance of a papillary adenocarcinoma

A
  1. Non-encapsulated infiltrative mass
  2. Firm - due to fibrosis
  3. White - due to fibrosis
45
Q

What do papillary adenocarcinomas look like histologically

A
  1. Epithelial papillary projections between which calcified capsules (psammoma bodies) are present
  2. Nulcei have clear central areas
46
Q

How do papillary adenocarcinomas metastasise

A

Via the lymphatic within the thyroid glands and the cervical lymph nodes

47
Q

Why does papillary adenocarcinoma have a good prognosis

A

As it is a slow-growing tumour

48
Q

Follicular adenocarcinoma vs follicular adenoma

A
  1. Adenocarcinoma shows blood vessels and invasion of capsule
49
Q

How does follicular adenocarcinoma metastasise

A

Blood stream to the bones and lungs

50
Q

Why does follicular adenocarcinoma have a good prognosis

A

Retains ability to take up 131-I

51
Q

Where are anapaestic carcinomas common

A

Elderly

52
Q

Why does anapalastic carcinomas have a poor prognosis

A

Because it results in rapid local invasion of structures such as the trachea

53
Q

What causes medullary carcinoma

A

Thyroid C-cells

54
Q

What do C-cells produce

A

Calcitonin

55
Q

Role of calcitonin

A

Lowers Ca levels in the blood:

  1. Inhibits osteoclast activity in bones
  2. Inhibits renal tubular absorption of Ca and phosphate
56
Q

What acts antagonistically to calcitonin

A

Vitamin D and PTH

57
Q

How does non-hodgkin’s lymphoma relate to thyroid

A

Originates in the thyroid in Hashimoto’s thyroiditis more commonly

58
Q

Where do lymphomas of the thyroid gland originate from

A

Neoplasms of mucosa-associated lymphoid tissue