5: Adrenal gland disorders - physiology, Addison's, Cushing's, primary aldosteronism Flashcards Preview

Endocrine Week 4 2017/18 COPY > 5: Adrenal gland disorders - physiology, Addison's, Cushing's, primary aldosteronism > Flashcards

Flashcards in 5: Adrenal gland disorders - physiology, Addison's, Cushing's, primary aldosteronism Deck (64)
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1
Q

What are the two parts of the adrenal gland?

A

Adrenal cortex

Adrenal medulla

2
Q

What are the three zones of the adrenal cortex?

A

Zona glomerulosa

Zona fasciculata

Zona reticularis

3
Q

What hormone is produced in the zona glomerulosa of the adrenal cortex?

A

Mineralocorticoids

e.g aldosterone

4
Q

What hormones are produced in the zona fasciculata of the adrenal cortex?

A

Glucocorticoids

cortisol

5
Q

What hormones are produced in the zona reticularis of the adrenal cortex?

A

Androgens

6
Q

Which cells, found in the adrenal medulla, secrete catecholamines?

A

Chromaffin cells

7
Q

What is the precursor molecule for steroid hormones?

A

Cholesterol

8
Q

Which axis regulates cortisol and androgen production by the adrenal cortex?

A

Hypothalamic-pituitary-adrenal axis

9
Q

What regulates aldosterone secretion by the adrenal cortex?

A

Renin-angiotensin system

Which is regulated by blood pressure & renal perfusion

10
Q

Corticosteroids bind to which kind of receptor?

A

Nuclear receptor

to alter transcription of protein

11
Q

What are some

a) cardio
b) metabolic
c) bone and soft tissue

effects of cortisol?

A

a) Increased BP, cardiac output and renal perfusion

b) Increased blood glucose level, increased lipolysis and proteolysis, central redistribution of fat

c) Reduced serum calcium (inc. rate of onset of osteoporosis), reduced rate of wound healing

12
Q

Cortisol (accelerates / dampens down) the immune response.

A

dampens down immune response

13
Q

Which physiological processes are corticosteroids used to suppress?

Give examples of specific diseases.

A

Immune response

so allergic diseases like asthma, eczema and anaphylaxis

Inflammation

so inflammatory diseases like RA, UC and Crohn’s disease

14
Q

In which diseases are exogenous corticosteroids used as a replacement for a deficiency in the body?

A

Adrenal insufficiency

e.g Addison’s disease (autoimmune reaction resulting in deficiency of cortisol), non-functioning adrenal tumours, non-functioning pituitary tumours

15
Q

Aldosterone is a (glucocorticoid / mineralocorticoid) produced by the adrenal cortex.

What is its function?

A

mineralocorticoid

Stimulates Na+ reabsorption in the distal tubules and collecting ducts, therefore controlling sodium homeostasis and blood pressure via RAAS

16
Q

What is the commonest cause of primary adrenal insufficiency?

A

Addison’s disease

Also consider Congenital adrenal hyperplasia

17
Q

Apart from Addison’s disease, what else can cause primary adrenal insufficiency?

A

Congenital adrenal hyperplasia

TB

Malignancy

18
Q

Adrenal insufficiency caused by a problem with the gland itself is (primary / secondary).

A

primary

19
Q

Addison’s disease is an ___ disease.

A

autoimmune

20
Q

What is destroyed by autoimmune reaction in Addison’s disease?

A

Adrenal cortex

21
Q

70% of people with Addison’s disease are positive for what?

A

Autoantibodies

22
Q

People with Addison’s disease are more likely to have other ___ diseases.

A

autoimmune

23
Q

What are the features of Addison’s disease?

A

Anorexia

Weight loss

Pigmentation

Dizziness and hypotension

Abdominal pain, vomiting, diarrhoea

24
Q

What kind of pigmentation is common in people with Addison’s disease?

A

Buccal pigmentation

25
Q

What will be seen on biochemical tests of people with Addison’s disease?

A

Hyponatraemia

Hyperkalaemia

Hypoglycaemia

26
Q

Which stimulation test is used to diagnose adrenal insufficiency?

A

Synacthen test

27
Q

In primary adrenal insufficiency, ACTH levels will be very (high / low).

A

high

causing skin pigmentation

28
Q

In secondary adrenal insufficiency, what will the patient’s ACTH be like?

Will they be pigmented?

A

Normal or low

No pigmentation

29
Q

Why are aldosterone levels low in people with Addison’s?

A

Destruction of adrenal cortex

30
Q

How should Addison’s disease be managed?

A

IV hydrocortisone (to replace cortisol)

Fludrocortisone (to replace aldosterone)

31
Q

What is the maintenance dose of oral hydrocortisone in patients with Addison’s disease?

A

15-30mg

32
Q

How many doses of hydrocortisone (15-30mg) in total are given to patients with Addison’s disease?

A

Two

to mimic diurnal rhythm

if you give after 6pm patient will be insomniac

33
Q

What must be monitored in patients being treated for Addison’s disease?

A

Blood pressure

Potassium level

34
Q

As in diabetes, patients with Addison’s disease must be educated on how to take their medication under which circumstance?

A

Sick days

35
Q

What is the emergency presentation of Addison’s disease?

A

Addisonian crisis

36
Q

What causes primary adrenal insufficiency?

A

Disease of adrenal gland itself

37
Q

What causes secondary adrenal insufficiency?

A

Problems with hypothalamic-pituitary axis

Iatrogenic (surgery, radiotherapy)

WITHDRAWAL OF HIGH DOSE STEROID THERAPY

38
Q

What is the most common cause of secondary adrenal insufficiency?

A

Withdrawal of high dose steroids

39
Q

How does high dose steroid cessation cause secondary adrenal insufficiency?

A

As they are similar to cortisol, they inhibit CRH/ACTH release by negative feedback and the adrenal glands atrophy

So when you take the patient off them, their adrenal glands aren’t capable of producing enough cortisol

> Insufficiency

40
Q

Are patients with secondary adrenal insufficiency pigmented?

A

No

normal / low ACTH

41
Q

What happens to aldosterone secretion in secondary adrenal insufficiency?

A

Nothing

no adrenal cortex damage

42
Q

How is secondary adrenal insufficiency treated?

A

Hydrocortisone (cortisol replacement)

43
Q

Patients with central obesity, i.e lemon on matchsticks appearance, should tip you off to which adrenal disorder?

A

Cushing’s disease/syndrome

44
Q

What causes Cushing’s syndrome?

A

Excess cortisol secretion by adrenal cortex

45
Q

What are the features of Cushing’s syndrome?

A

Central obesity, abdominal striae

Acne

Moon face

Hypertension

Easy bruising

Proximal myopathy

i.e lots

46
Q

Cushing’s syndrome is either ACTH ___ or ___.

A

dependent , independent

47
Q

What causes 70% of Cushing’s disease?

A

Pituitary adenoma producing ACTH

48
Q

As Cushing’s disease is caused by cortisol excess, how is it diagnosed?

A

Dexamethasone suppression test

49
Q

If a patient passes a low dose dexamethasone suppression test, they don’t have Cushing’s.

If a patient fails the test, what is done next?

A

More tests

e.g overnight dexamethasone suppression test

50
Q

What is the commonest cause of cortisol excess?

A

Prolonged high dose steroid therapy

causes atrophy of ACTH-producing cells and adrenal atrophy

must be weaned off steroids otherwise they will develop adrenal insufficiency

51
Q

Patients presenting with hypertension under the age of 40 should always be checked for ___ adrenal disorders.

A

secondary

52
Q

Which adrenal diseases produce

a) hypotension
b) hypertension with hyperglycaemia
c) hypertension with hypokalaemia?

A

a) Adrenal insufficiency
b) Cushing’s disease
c) Conn’s syndrome / primary aldosteronism

53
Q

What is primary aldosteronism?

A

Excess aldosterone production unregulated by renin-angiotensin system

54
Q

Why does primary aldosteronism cause hypokalaemia?

A

Loads of K+ excreted by kidneys

55
Q

As it causes hypertension, many patients with Conn’s syndrome die of ___ disease.

A

cardiovascular

56
Q

What are the main features of primary aldosteronism?

A

Hypertension

Hypokalaemia

Metabolic alkalosis (as H+ ions leave with potassium)

57
Q

What are the two main causes of primary aldosteronism?

A

Adrenal adenoma - CONN’S SYNDROME

Bilateral adrenal hyperplasia

58
Q

Primary aldosteronism can be caused by mutations for which channels?

A

Potassium channels

59
Q

Which tests are used first and second-line to diagnose primary aldosteronism?

A

1. Aldosterone / renin ratio (A/R), abnormal if raised

2. Saline suppression test

give patient 2L saline IV, if aldosterone doesn’t drop by at least 50% then they have PA

60
Q

Once you have confirmed that a patient has primary aldosteronism, how do you find out the cause?

A

Adrenal CT scan

61
Q

Which scan shows the metabolic activity of cells and can be combined with a CT to confirm primary aldosteronism?

A

PET-CT scan

Gold-standard for diagnosing primary aldosteronism

62
Q

If a PET-CT scan shows adrenal hyperplasia to be

a) unilateral (or an adrenal adenoma)
b) bilateral

how is it treated?

A

a) Unilateral adrenalectomy

b) Aldosterone antagonists

63
Q

What is an aldosterone antagonist used to treat primary aldosteronism caused by bilateral adrenal hyperplasia?

A

Spironolactone

64
Q

Apart from PET-CT, what test can be done to confirm if adrenal disease causing primary aldosteronism is unilateral or bilateral?

A

Adrenal vein sampling