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Phase 2 > Endocrine 2 > Flashcards

Endocrine 2 Flashcards

1
Q

Describe the characteristics of water-soluble hormones

A

Transported unbound
Short half-life
Cleared fast
Bind to surface receptors on cells

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2
Q

Give some examples of water-soluble hormones
Where are these stored?

A

Peptides
Monoamines
Both stored in vesicles before secretion

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3
Q

Describe the characteristics of fat-soluble hormones

A

Transported bound to protein
Diffuse into cells
Long half-life
Cleared slowly

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4
Q

Give examples of fat-soluble hormones
When are they secreted?

A

Thyroid hormones
Steroids
Secreted upon demand

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5
Q

What does the endocrine system comprise of?

A

Pituitary gland
Thyroid
Parathyroid
Adrenal glands
Pancreas
Ovary
Testes

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6
Q

first lecture of endo

A

skipped to regulation of appetitie

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7
Q

How do you calculate BMI?

A

Weight (kg) / height squared (m2)

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8
Q

What are the ranges for BMI ?

A

< 18.5 underweight
18.5 - 24.9 normal
25 - 29.9 overweight
30 - 39.9 obese
> morbidly obese

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9
Q

Risks of obesity

A

Type II diabetes
HTN
Coronary artery disease
Stroke
Osteoarthritis
Obstructive sleep apnoea
Carcinoma - breast, endometrium, prostate, colon

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10
Q

What plays a central role in appetite regulation?

A

Hypothalamus

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11
Q

Why is the anatomy of the anterior pituitary unusual?

A

No arterial blood supply

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12
Q

Describe the HPA axis

A

Hypothalamus -> CRH
Pituitary -> ACTH
Adrenal cortex -> cortisol

Cortisol decreases the activity of Hypothalamus & Pituitary
∴ less CRH + ACTH produced

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13
Q

Describe the HPT axis

A

Hypothalamus -> ↑ TRH
Pituitary -> ↑ TSH
Thyroid gland -> ↑ T3 + T4

T3 + T4 decreases activity of Hypothalamus and Pituitary
∴ ↓ TRH + TSH produced

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14
Q

Describe the GH/IGF-I axis with the result of increasing GH

A

Hypothalamus -> ↑ GHRH
Pituitary -> ↑ GH
Liver -> ↑ IGF-I

IGF-I decreases activity of hypothalamus
∴ ↓ GHRH

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15
Q

Describe the GH/IGF-I axis with the result of decreasing GH

A

Hypothalamus -> ↑ SMS (inhibits GH production)
Pituitary -> ↓ GH
Liver -> ↓ IGF-I

IGF-I decreases production of GH
∴ ↓ IGF-I = ↑ GH

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16
Q

What is the mean age and mean duration of symptom presentation of Acromegaly?

A

mean age = 44 years
mean duration = 7 years

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17
Q

What are some co-morbidities of Acromegaly?

A

HTN and heart disease
Sleep apnoea
Arthritis
Insulin-resistant diabetes (type 2)
Cerebrovascular events & headaches

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18
Q

What are some questions you could ask to find out the clinical features of acromegaly?

A

Are rings still fitting you?
Is shoe size changing?
Teeth more separate?

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19
Q

When is acromegaly excluded?
(Clinical findings)

A

Random GH < 0.4 ng/ml
Normal IGF-I

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20
Q

Gold standard for Acromegaly

A

75gm Oral glucose tolerance test

Acromegaly excluded if :
IGF-I normal
and
OGTT nadir GH <1ng/ml

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21
Q

What are the aims of treatment in acromegaly?

A

Restoration of basal GH and IGF-I to normal
Symptom relief
Reverse of visual/soft tissue changes
Stop further skeletal deformity
Normalise pituitary function

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22
Q

Why can’t you rely on random GH to diagnose acromegaly?

A

Because GH has pulsatile secretion

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23
Q

What are some issues that make transsphenoidal pituitary surgery harder?

A

Large tumour
Invasiveness - if in cavernous sinus

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24
Q

How does the size of an adenoma (specifically when treating acromegaly) affect the surgical cure rate?

A

If < 1cm, cure rate ~90%
If > 1cm, cure rate ~ <50%

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25
Q

What are problems of radiotherapy when treating acromegaly?

A

Delayed response
Hypopituitarism
Rare 2ndary tumours
Bc close to eyes, could cause damage

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26
Q

What medication can be used to block GH and ∴ treat acromegaly?

A

Somatostatin analogues
Dopamine agonists
GH receptor antagonist

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27
Q

What are some advantages of dopamine agonists when treating acromegaly?

A

No hypopituitarism
Oral administration
Rapid onset

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28
Q

What are some disadvantages of dopamine agonists when treating acromegaly?

A

Relatively ineffective
Side effects

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29
Q

What are the advantages of using Cabergoline vs bromocriptine (both dopamine agonists used to treat acromegaly)?

A

Cabergoline is more potent, fewer side effects
Twice weekly

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30
Q

When are dopamine agonists especially useful in treating acromegaly?

A

When tumour is co-secreting GH and prolactin

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31
Q

What are some disadvantages of somatostatin analogues?

A

Injectable
Side effects

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32
Q

What are some determinants of efficacy of somatostatin analogues?

A

GH levels
Tumour size
SMS receptor expression

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33
Q

Describe the onset of acromegaly

A

Insidious

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34
Q

What are some effects of prolactin?

A

Menstrual irregularity
Infertility
Galactorrhoea
Low libido
Low testosterone in men

35
Q

What type of visual defect can you get with a pituitary tumour?

A

Bi-temporal hemianopia

36
Q

Describe the location of the pituitary

A

Sits within the sella turcica at the base of brain

37
Q

Name some examples of hormones that are secreted from the anterior pituitary

A

Thyroid stimulating hormone (TSH)
Adrenocorticotrophic hormone (ACTH)
Prolactin
Growth hormone (GH)
Gonadotrophic hormones

38
Q

Name some examples of hormones that are secreted from the posterior pituitary

A

Oxytocin
Anti-diuretic hormone (ADH)

39
Q

Describe the blood supply of the anterior pituitary

A

No direct arterial blood supply
Receives blood through portal venous circulation from hypothalamus

40
Q

Describe how prolactinoma may come about

A

Ant. pituitary enlarges
Impinges on hypothalamus
Hypothalamus produces less dopamine
∴ prolactin secreted is NOT suppressed

41
Q

What can pituitary tumours cause?

A
  1. Pressure on local structures - optic nerve ∴ bitemporal hemianopia
  2. Pressure on normal pituitary ∴ hypopituitarism
  3. Could be a functioning tumour
    e.g. prolactinoma, acromegaly, cushing’s
42
Q

Describe symptoms if a pituitary tumour puts pressure on local structures

A

Could go up and stretch the dura, causing headaches
Visual field defects (bitemporal hemianopia)
Could go sideways into medial temporal lobe, cause cranial nerve palsies and seizures
If goes down through bone, CSF fluid leakage

43
Q

Describe hypopituitary signs

A

Pale
No body hair
Central obesity

44
Q

Why is a benign adenoma NOT a differential for diabetes insipidus?

A

Bc diabetes insipidus is caused by dysfunctional posterior pituitary and benign adenomas only are found anteriorly!

45
Q

What is a carcinoid tumour?

A

Type ofneuroendocrine tumourthat grows from neuroendocrine cells

46
Q

What are the 3 layers of the adrenal cortex and what do they produce?

A

GFR makes good SEX*

Zona glomerulosa - mineralcorticoids - aldosterone (AM)

Zona fasciculata - glucocorticoids - cortisol (GC)

Zona reticularis - androgens - sex hormones

47
Q

What is the difference between Acromegaly and Gigantism?

A

Gigantism-XS GH productioninchildren BEFORE fusionof theepiphysesof thelong bones
Acromegaly-XS GHinadults

48
Q

Describe a bitemporal hemianopia

A

Loss of vision on outer half of both eyes

49
Q

What inhibits the release of GH?

A

Somatostatin !
Dopamine
High levels of glucose

50
Q

Where is prolactin secreted from?

A

Anterior Pituitary

51
Q

What inhibits the release of of prolactin?

A

Dopamine

52
Q

Where is dopamine produced?

A

Hypothalamus

53
Q

What is prolactin?

A

Hormone produced by lactotrophs in ant. pituitary gland

54
Q

Define prolactinoma

A

Lactroph cell tumour of the pituitary

55
Q

Define microadenoma

A

Tumour < 1cm

56
Q

Define macroadenoma

A

Tumour > 1cm

57
Q

What is a circadian rhythm?

A

Physical, mental and behavioural changes that follow a daily cycle

58
Q

What is 1° adrenal insufficiency also called?

A

Addison’s disease

59
Q

What is 2° adrenal insufficiency also called?

A

Hypopituiritarism

60
Q

What is the most common cause of primary adrenal insufficiency worldwide?

A

TB

61
Q

What is the most common cause of primary adrenal insufficiency in the UK?

A

Addison’s (autoimmune adrenalitis)

62
Q

Aldosterone acts on the kidney to :

A

Increase sodium reabsorption from distal tubule
& increase potassium excretion from distal tubule

63
Q

What is the fun key phrase to remember for Addison’s?

A

Tanned, Toned (fit and ready), Tired, Tearful

64
Q

If Hypothalamus releases TRH,
What does the pituitary release?
What is the target organ?
What does the target organ release?
What is the effect of the hormones?

A

TSH
Thyroid
T3 + T4
Metabolism

65
Q

If Hypothalamus releases CRH,
What does the pituitary release?
What is the target organ?
What does the target organ release?
What is the effect of the hormones?

A

ACTH
Adrenal cortex
Cortisol
Fat metabolism

66
Q

If Hypothalamus releases GnRH,
What does the pituitary release?
What is the target organ?
What does the target organ release?
What is the effect of the hormones?

A

FSH/LH
Gonads
Oestrogen/Testosterone
Menstrual cycle, Sex

67
Q

If Hypothalamus releases GHRH,
What does the pituitary release?
What is the target organ?
What does the target organ release?
What is the effect of the hormones?

A

GH
Liver
IGF-I
Growth & development

68
Q

If Hypothalamus releases Dopamine,
What does the pituitary release?
What is the target organ?
What does the target organ release?
What is the effect of the hormones?

A

Inhibits prolactin
Breast
/
Milk production

69
Q

What inhibits TSH?

A

Somatostatin

70
Q

When treating adrenal insufficiency, what must you remember?

A

Double dose of steroids if infection, trauma, surgery or nightshift work

71
Q

What is the cause of Goitre?

A

Iodine deficiency

72
Q

If a patient presents with weight loss, heat intolerance, palpitations, sweating, anxiety etc, what should you be thinking?
and ∴ what should you do?

A

Problem with thyroid
∴ order a TSH test (cheap, doesn’t take long and can quickly determine the problem)

73
Q

What are T3/T4 necessry for?

A

3 M’s :
Movement, Mentation & Metabolism

74
Q

Where and when is Parathyroid hormone secreted?

A

By Chief cells in response to hypocalcaemia

75
Q

Describe the action of Parathyroid hormone

A

↑ Osteoclast activity (∴ release Ca2+ & phosphate from bone) -> RAPID!

↑ Intestinal calcium absorption -> slow & indirect !

↑ Ca2+ & ↓ phosphate reabsorption in kidney

↑ Vitamin D production

Overall, ↑ Ca2+ & ↓ Phosphate

76
Q

What is calcitriol release stimulated by?

A

↓ Plasma Ca2+
↓ Plasma phosphate
Parathyroid hormone (PTH)

77
Q

What is the role of Vitamin D / Calcitriol / 1, 25-dehydroxycholecalciferol ?

A

↑ Ca2+ & Phosphate absorption in gut
Enhanced bone turnover by ↑ osteoclasts
↑ Ca2+ and phosphate reabsorption in kidneys
Inhibits PTH release - neg feedback

78
Q

What is calcitriol?

A

The active form of Vitamin D

79
Q

Where is calcitonin made?

A

In C-cells of thyroid

80
Q

What effect does calcitonin have on plasma Ca2+ and phosphate?

A

↓ Ca2+ and phosphate

81
Q

What does HYPOcalcaemia cause?

A

Paraesthesia
Muscle spasms
Seizures
Basal ganglia calcification
Cataracts
ECG abnormalities (Long QT)
Osteomalacia - vit D def

CHVOSTEK’S SIGN

82
Q

How do you look for Chvostek’s sign?

A

Tap facial nerve and look for facial spasm

83
Q

What are paraganglia cells?

A

Chromaffin cells that secrete adrenaline

Phase 2 (24 decks)

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