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Phase 2a > Endocrinology > Flashcards

Endocrinology Flashcards

1
Q

Define Endocrinology

A

Study of hormones (and their gland of origin), their receptors, the intracellular signalling pathways, and their associated disease

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2
Q

Define endocrine

A

Glands ‘pour’ secretions directly into blood stream (are ductless)

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3
Q

Define exocrine

A

(outside) - glands pour secretions through a duct to site of action

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4
Q

Define autocrine

A

Feedback on the same cell that secreted the hormone

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5
Q

4 main differences between water and fat soluble hormones

A

Water-soluble

  • Transport: Unbound
  • Cell interaction: bind to surface receptor
  • Half-life: short
  • Clearance:fast

Fat-soluble

  • Transport: Protein bound
  • Cell interaction: diffuse into cell
  • Half-life: long
  • Clearance: slow
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6
Q

4 hormone classes

A
  • Peptides
  • Amines
  • Iodothyronines
  • Cholesterol derivatives & steroids
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7
Q

Example of a peptide hormone

A

Insulin

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8
Q

3 characteristic features of peptide hormones

A
  • Stored in secretory granules
  • Released in pulses or bursts
  • Cleared by tissue or circulating enzymes
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9
Q

2 example of amine hormones

A

Adrenaline & noradrenaline

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10
Q

When noradrenaline & adrenaline are broken down, what is formed & why is this important?

A

Normetanephrine & metanephrine

Have longer half lives & so can be measured in serum

Act as indicators of noradrenaline & adrenaline activity

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11
Q

5 methods of controlling hormone action

A
  • Hormone metabolism
  • Hormone receptor induction
  • Hormone receptor down regulation
  • Synergism
  • Antagonism
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12
Q

Define appetite

A

Desire to eat

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13
Q

Define hunger

A

Need to eat

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14
Q

Define anorexia

A

Lack of appetite (desire to eat)

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15
Q

What body structure controls eating?

A

Hypothalamus

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16
Q

Where is the hunger centre?

A

Lateral hypothalamus

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17
Q

Where is the satiety centre?

A

Ventromedial hypothalamic nucleus

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18
Q

Role of leptin

A

Switches off appetite

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19
Q

Role of peptide YY in appetite

A

Inhibits gastric motility

Reduces appetite

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20
Q

Role of CCK in appetite

A

Delays gastric emptying

Gall bladder contraction

Insulin release

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21
Q

Role of ghrelin in appetite

A

Stimulates GH release

Stimulates appetite

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22
Q

When is PTH secreted?

A

It increases the absorption of Ca2+ and is secreted when Ca2+ levels fall.

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23
Q

Causes of hypercalcaemia

A
  • Malignancy
    • Bone mets, myeloma, PTHrP - PTH related peptide (acts like PTH, but isn’t PTH), lymphoma
  • Primary hyperparathyroidism
  • Thiazides
  • Thyrotoxocosis
  • Sarcoidosis
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24
Q

Symptoms of hypercalcaemia

A
  • Thirst
  • Nausea
  • Constipation
  • Confusion → coma
  • Renal stones
  • ECG abnormalities
    • short QT
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25
Q

Causes of hypocalcaemia

A

Osteomalacia

  • Caused by vit D deficiency
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26
Q

Action of PTH in terms of phosphate?

A

PTH acts to push phosphate out of the kidneys

(reduces reabsorption at PCT)

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27
Q

2 categories of insulin

A

Basal insulin

Prandial/meal-time insulin

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28
Q

What are the 2 main differences between basal & prandial insulins?

A

Basal

  • Work over a period of time
  • Cover the period between meals

Prandial

  • Rapid acting
  • Given with a meal
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29
Q

Advantages of giving basal insulin to a patient with T2 diabetes mellitus?

A

Simple for patients to adjust themselves based on fasting

Carries on with oral therapy

Less risk of hypoglycaemia at night

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30
Q

Disadvantages of giving basal insulin to a patient with T2 diabetes mellitus?

A

Doesn’t cover meals

Best used with long-acting insulin analogues which are considered expensive

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31
Q

Advantages of giving pre-mixed insulin to a patient with T2 diabetes mellitus?

A

Both basal & prandial components in one preparation

Can cover insulin requirements through most of the day

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32
Q

Disadvantages of giving pre-mixed insulin to a patient with T2 diabetes mellitus?

A

Not physiological

Requires constant meal & exercise pattern

Increased risk for nocturnal hypoglycaemia

Increased risk for fasting hyperglycaemia if basal component doesn’t last long enough

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33
Q

Describe the blood supply to the anterior pituitary gland

A

Receives no arterial blood supply

Receives blood through portal venous circulation from the hypothalamus

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34
Q

Describe the 4 stages of the pituitary-thyroid axis

A
  1. Hypothalamus secretes TRH
  2. Stimulates pituitary to secrete TSH
  3. Stimulates thyroid to secrete T4&T3
  4. T4&T3 inhibit the hypothalamus & pituitary
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35
Q

What will happen to TSH levels if you do not have a thyroid?

A

TSH will increase

(no T4&T3 produced so hypothalamus & pituitary not inhibited)

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36
Q

In the menopause, the ovaries fail. What will happen to levels of oestrogen, LH & FSH?

A

Oestrogen decreases

LH & FSH increase

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37
Q

3 main problems caused by pituitary disease

A
  • Pressure on local structure, eg optic nerve
  • Pressure on normal pituitary → hypopituitarism
  • Functioning tumour → eg prolactinoma
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38
Q

How does a meningioma usually present?

A

Loss of VA

Endocrine dysfunction

Visual field defects

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39
Q

What is lymphocytic hypophysitis?

A

Inflammation of the pituitary gland due to an autoimmune reaction

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40
Q

What is important to measure when testing the pituitary-thyroid axis?

A

Ft4

(free T4)

41
Q

If you have a primary hypothyroidism, what would you expect the levels of TSH & Ft4 to be like?

A

Raised TSH

Low Ft4

(primary = problem in the thyroid)

42
Q

If you have a hypopituitarism, what would you expect the levels of TSH & Ft4 to be like?

A

Low Ft4

Normal or low TSH

43
Q

What does Grave’s disease result in?

A

Overproduction of thyroid hormones

44
Q

If you have Grave’s disease, what would you expect the levels of TSH & Ft4 to be like?

A

Low TSH

High Ft4

45
Q

What is thyrotoxicosis?

A

The clinical manifestation of excess thyroid hormone action at the tissue level due to inappropriately high circulating thyroid hormone concentrations

46
Q

Describe the half life of vasopressin & explain why this is relevant?

A

Short half life

Allows fine tuning of water levels

47
Q

Which of the following is not under the control of the pituitary gland?

  • Thyroid
  • Adrenal cortex
  • Adrenal medulla
  • Testis
  • Ovary
A

Adrenal medulla

48
Q

Which of the following statements is false?

  • The pituitary gland lies in the sella turcica
  • The weight of the pituitary gland is around 0.5g
  • ACTH is secreted from the pituitary during stress
  • The pituitary regulates calcium metabolism
  • The anterior and posterior pituitary are distinct on an MRI scan
A

The pituitary regulates calcium metabolism

(regulated by parathyroid)

49
Q

In men all of the following are mainly produced in the adrenal cortex except…?

  • DHEAS
  • Testosterone
  • Aldosterone
  • 17-OH progesterone
  • Androstenedione
A

Testosterone

50
Q

Where is testosterone produced?

A

The testis

51
Q

What is AVP?

A

Vasopressin

52
Q

Which of the following regarding AVP is false?

  • AVP levels have a linear relationship with serum osmolality
  • Is produced in the pituitary gland
  • Stimulates reabsorption of water in the collecting duct of the nephron
  • In hypotension, baroreceptors predominantly activate ADH production & secretion
  • Further AVP production is no longer effective once urine osmolality has reached a plateau
A

Is produced in the pituitary gland

(it is produced in the hypothalamus & stored in the posterior pituitary)

53
Q

Where is growth hormone’s main site of action to stimulate IGF1 release?

  • Bone
  • Liver
  • Adrenal cortex
  • Muscle
  • Pancreas
A

Liver

54
Q

Hypothalamic hormones act to mainly stimulate the release of all these hormones except

  • ACTH
  • GH
  • TSH
  • Proalctin
  • LH
A

Prolactin

(dopamine inhibits prolactin)

55
Q

The following are typical features of excess GH secretion except?

  • Polyuria
  • Joint pains
  • Sweating
  • Hypotension
  • Headaches
A

Hypotension

(high bp is common)

56
Q

The following hormones all have a circadian rhythm except?

  • Cortisol
  • Testosterone
  • DHEA
  • 17OH progesterone
  • Thyroxine (T4)
A

Thyroxine

57
Q

Typical features of cortisol deficiency include the following except?

  • Hypotension
  • Muscle aches
  • Weight loss
  • Hyperglycaemia
  • Lethargy
A

Hyperglycaemia

58
Q

Effect of cortisol on blood glucose

A

Cortisol = stress hormone

Makes blood glucose rise

59
Q

A 38 year old lady presented with weight gain, menorrhagia (heavy periods) and constipation. She is most likely suffering from?

  • Cushing’s syndrome
  • Addison’s disease
  • Primary hypothyroidism
  • Graves disease
  • Acromegaly
A

Primary hypothyroidism

60
Q

What causes Cushing’s syndrome?

A

Levels of cortisol in the body are too high

61
Q

What causes the symptoms of Addison’s disease?

A

The adrenal gland is damaged in Addison’s disease, so it does not produce enough cortisol or aldosterone.

62
Q

What is Graves disease also known as?

A

Hyperthyroidism

63
Q

Which test would you likely want to perform in a patient with proximal muscle weakness, purple striae and thin skin?

  • Synacthen test
  • Overnight dexamethasone suppression test
  • Insulin tolerance test
  • Glucagon test
  • Skin allergy tests
A

Overnight dexamethasone suppression test

64
Q

What is dexamethasone suppression test used to diagnose

A

Cushing’s syndrome (excess cortisol)

Normally, when the pituitary gland makes less ACTH, the adrenal glands make less cortisol.

Dexamethasone, which is like cortisol, lowers the amount of ACTH released by the pituitary gland. This in turn lowers the amount of cortisol released by the adrenal glands.

After a dose of dexamethasone, cortisol levels often stay very high in people who have Cushing’s syndrome.

65
Q

What is the synacthen test used to diagnose?

A

Addison’s disease

66
Q

How does the Synacthen test work?

A

During the synacthen test you are given a chemical called tetracosactide (synacthen is the commercial name of this chemical). Tetracosactide is a chemical copy of ACTH.

ACTH is the hormone released by your pituitary gland, which stimulates the adrenals to produce cortisol. If the adrenal glands are working properly they should respond to the tetracosactide by producing cortisol. Levels of cortisol are checked by taking a blood sample.

If levels of cortisol remain low, despite the tetracosactide injection, this suggests there is a problem with the function of the adrenal glands (ADDISON’S)

67
Q

What is the insulin tolerance test (ITT) used for?

A

The ITT is used to test how much ACTH and cortisol you can produce and how much growth hormone is available when your body is stressed.

The ‘stress’ in the test is low blood sugar. This is caused by an injection of insulin, under very controlled conditions.

68
Q

A 24 year old girl presented with hirsutism, oligomenorrhoea and acne. What test would you likely carry out from the ones below?

  • Ultra sound adrenals
  • Ultra sound ovaries
  • MRI ovaries
  • CT scan adrenals
  • Prolactin
A

(oligomenorrhoea = infrequent periods. Hirsutism = excess hair most often noticeable around the mouth and chin. )

Ultra sound ovaries

(these are typical presenting features of PCOS)

69
Q

A 54 year old gentleman presented with hyponatraemia.

All the following conditions need excluding before confirming SIADH except?

  • Hypothyroidism
  • Hypervolaemia
  • Euvolaemia
  • Adrenal insufficiency
  • Diuretic use
A

Euvolaemia (= normal amount of body fluids)

(SIADH = excess ADH)

70
Q

Normal serum sodium levels?

A

135-144mmol/L

71
Q

A 66 year old gentleman had a serum sodium of 124 mmol/l, serum osmolality 265 mmol/l and a urine sodium of 52 mmol/l. What would you like to perform first?

  • Chest X-ray
  • CT brain
  • Skin turgor and jugular venous pressure test
  • Thyroid function test
  • Synacthen test
A

Skin turgor and jugular venous pressure test

(needed to diagnose SIADH)

72
Q

5 Essential criteria for diagnosis of SIADH

A
  • Hyponatraemia
  • Plasma hypo-osmolality
  • Urine osmolality > 100 mOsm/Kg
  • Clinical euvolaemia
  • Increased urinary sodium excretion (>30mmol/L with normal salt and water intake)
73
Q

How can you diagnose clinical euvolaemia

A

No clinical signs of hypovolaemia (decreases in BP, tachycardia, decreased skin turgor, dry mucous membranes)

No clinical signs of hypervolaemia (oedema, ascites)

74
Q

The following are most likely causes of SIADH except?

  • MS
  • Lung abscess
  • Subdural haemorrhage
  • Lymphoma
  • Cerebrovascular accident
A

MS

75
Q

A 28 year old presented with a microprolactinoma. What is the most unlikely symptom?

  • Galactorrhoea
  • Oligomenorrhoea
  • Decreased sexual appetite
  • Headaches
  • Visual field defects
A

Visual field defects

76
Q

The following suppress appetite except?

  • Peptide YY
  • Ghrelin
  • CCK
  • GLP1
  • Glucose
A

Ghrelin

77
Q

The main adipose signal to the brain is

  • CCK
  • Neuropeptide Y
  • Leptin
  • Agouti-related peptide
  • Adiponectin
A

Leptin

78
Q

A 65 year old lady is diagnosed with SIADH. Her sodium is 123mmol/l. What is your first line of management?

  • If symptomatic, treat with fluid restriction
  • If she is asymptomatic I will treat with hypertonic saline
  • If she is asymptomatic I will treat with fluid restriction
  • If she is asymptomatic I will repeat the sodium level the next day
  • If she is asymptomatic I will give normal saline
A

If she is asymptomatic I will treat with fluid restriction

79
Q

A patient with Addison’s disease presents with a chest infection. What do you do?

  • Omit his steroids to avoid immunosuppression
  • Stop his steroids as they have precipitated a chest infection
  • Double his steroid dose whilst unwell
  • Keep him on his usual steroid dose
  • None of the above
A

Double steroid use whilst unwell

80
Q

Define primary, secondary and tertiary hypogonadism

A

Primary hypogonadism - problem with gonad

Secondary - problem with pituitary

Tertiary - problem with hypothalamus

81
Q

Describe LH & testosterone levels which are typical of secondary hypogonadism?

A

(problem with pituitary)

Low LH & ∴ low testosterone

82
Q

Typical features of hypogonadism in a male include the following except?

  • Decreased sweating
  • Joint & muscular aches
  • Decreased sexual appetite
  • Decreased hair growth
  • Asymptomatic
A

Hypogonadism → low testosterone

Decreased sweating

83
Q

A patient has a noon testosterone level below the normal range. What will you do?

  • Treat with testosterone gel
  • Repeat the test at 0900h and check for symptoms
  • Repeat the test at noon to keep things equal
  • Refer to endocrinology
  • Ignore it
A

Repeat the test at 0900h and check for symptoms

84
Q

The first line treatment for a patient with a symptomatic prolactinoma is usually:

  • Radiotherapy
  • Transphenoidal surgery
  • Dopamine agonists
  • Transfrontal surgery
  • Somatostatin analogues
A

Dopamine agonist

dopamine inhibits prolactin

85
Q

Typical visual field defect of a patient with a large pituitary mass is?

  • Unilateral quadrantanopia
  • Bitemporal hemianopia
  • Complete unilateral visual field loss
  • Complete bilateral visual field loss
  • None of the above
A

Bitemporal hemianopia

86
Q

Satiety is…

A

The physiological feeling of no hunger

87
Q

The centres of appetite regulation in the brain are mainly found in the…

A

Hypothalamus

88
Q

What does MODY stand for?

A

Maturity onset diabetes of the young

89
Q

Describe MODY

A

A rare form of diabetes which is different from both T1&T2 DM

It runs strongly in families & is caused by a mutation in a single gene

90
Q

4 clinical signs a patient has MODY?

A
  • Parents affected with diabetes
  • Absence of islet autoantibodies
  • Evidence of non-insulin dependence
    • Good control of low dose insulin
    • No ketosis
    • Measurable C-peptide
  • Sensitive to sulphonylurea
91
Q

Cause of Addison’s disease

A

Destruction of the adrenal gland - autoimmune

92
Q

Cause of secondary adrenal insufficiency

A

No stimulation of the adrenal gland due to hypopituitarism

93
Q

Define hyperosmolar hyperglycaemic state (HHS)

A

Characterised by profound hyperglycaemia, hyperosmolality and volume depletion in the absence of significant ketoacidosis

A serious complication of diabetes

94
Q

Most common presentation of thyroid cancer

A

An asymptomatic thyroid nodule

95
Q

Risk factors for thyroid cancer

A

Head & neck irradiation

Female

Family history

96
Q

Most important diagnostic test for thyroid cancer

A

Fine-needle aspiration

97
Q

Treatment for thyroid cancer

A

Usually total thyroidectomy

98
Q

What is the difference between Cushing’s syndrome & disease?

A

Cushing’s disease is a specific type of Cushing’s syndrome

When a pituitary tumour makes too much cortisol

Phase 2a (12 decks)

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