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Year 2 - BRS > 3.10 - Adrenal disorders 1/2 > Flashcards

3.10 - Adrenal disorders 1/2 Flashcards

1
Q

What hormones does the adrenal cortex produce and from which zones?

A

Corticosteroids

  • mineralocorticoids (aldosterone) - zona glomerulosa
  • glucocorticoids (cortisol) - zona fasciculata and zona reticularis
  • small amount of sex steroids (androgens, oestrogens) - zona fasciculata and zona reticularis
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2
Q

What is the precursor to steroid hormones?

A

Cholesterol

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3
Q

What is an enzyme?

A
  • protein that catalyses a specific reaction
  • various enzymes are present in cells
  • specific enzymes catalyse the synthesis of particular alterations to the molecule (cholesterol)
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4
Q

What are the key steps in the synthesis of aldosterone?

A
  1. cholesterol side chain cleavage produces pregnenolone
  2. 3-beta-hydroxysteroid dehydrogenase oxidises C3 to form progesterone
  3. 21 hydroxylase adds OH to C21 to form 11-deoxycorticosterone
  4. 11 hydroxylase adds OH to C11 to form corticosterone
  5. 18 hydroxylase adds OH to C18 to form aldosterone
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5
Q

What are the key steps in the synthesis of cortisol?

A
  1. cholesterol side chain cleavage produces pregnenolone
  2. 3-beta-hydroxysteroid dehydrogenase oxidises C3 to form progesterone
  3. 17 hydroxylase adds OH to C17 to form 17-hydroxyprogesterone
  4. 21 hydroxylase adds OH to C21 to form 11-deoxycortisol
  5. 11 hydroxylase adds OH to C11 to form cortisol
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6
Q

What are the key steps in the synthesis of androgens/oestrogens?

A
  1. cholesterol side chain cleavage produces pregnenolone
  2. 3-beta-hydroxysteroid dehydrogenase oxidises C3 to form progesterone
  3. 17 hydroxylase adds OH to C17 to form 17-hydroxyprogesterone
  4. sex steroids
  5. androgens
  6. oestrogen
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7
Q

What are the effects of angiotensin II on the adrenals?

A
  • side chain cleavage
  • 3 beta hydroxysteroid dehydrogenase
  • 21 hydroxylase
  • 11 hydroxylase
  • 18 hydroxylase
  • = cause aldosterone release
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8
Q

What is a summary of the function of aldosterone?

A

Controls blood pressure, increases sodium and lowers potassium

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9
Q

What are the effects of ACTH on the adrenals?

A
  • side chain cleavage
  • 3 beta hydroxysteroid dehydrogenase
  • 17 hydroxylase
  • 21 hydroxylase
  • 11 hydroxylase
  • = cortisol release
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10
Q

What kind of rhythm does cortisol have?

A

Diurnal rhythm - increase starts early morning, peaks around 8:30/9, decreases again

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11
Q

What is Addison’s disease?

A

Primary adrenal failure (lose aldosterone and cortisol - salt loss and eventual death due to low BP)

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12
Q

What is the commonest cause of Addison’s disease in the UK?

A

Autoimmune disease where the immune system decides to destroy the adrenal gland

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13
Q

What is the commonest cause of Addison’s disease worldwide?

A

Tuberculosis of the adrenal glands

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14
Q

What does the pituitary do in response to low cortisol and aldosterone due to Addison’s disease?

A

Pituitary starts secreting lots of ACTH and hence MSH (melanocyte stimulating hormone)

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15
Q

What are the features of Addison’s disease? (3)

A
  • increased pigmentation
  • autoimmune vitiligo may coexist
  • no cortisol or aldosterone, so low blood pressure
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16
Q

Why do patients with Addison’s disease have a good tan?

A
  • pro-opio-melanocortin (POMC) is a large precursor protein that is cleaved to form a number of smaller peptides including ACTH, MSH and endorphins
  • people with Addison’s increase ACTH to try and increase cortisol/aldosterone
  • since ACTH comes from POMC, pathologically high ACTH = increased MSH = increased melanin –> tanned
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17
Q

What are two types of dysfunction in adrenocortical failure?

A
  • adrenal glands destroyed
  • enzymes in the steroid synthetic pathway not working - congenital adrenal hyperplasia
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18
Q

What are three causes of adrenocortical failure?

A
  • tuberculous Addison’s disease (commonest worldwide)
  • autoimmune Addison’s disease (commonest in UK)
  • congenital adrenal hyperplasia
19
Q

What are the consequences of adrenocortical failure? (6)

A
  • fall in BP (postural hypotension)
  • loss of salt in urine (low sodium in plasma = hyponatraemia)
  • increased plasma potassium (less K+ excreted in urine = hyperkalaemia)
  • low glucose due to glucocorticoid deficiency
  • high ACTH = increased pigmentation
  • eventual death due to severe hypotension
20
Q

What are the tests for Addison’s disease?

A
  • clinical suspicion - fatigue, low Na+, high K+
  • 9am cortisol (low) and ACTH (high)
  • short synACTHen test where you do a cortisol blood test then give 250ug synACTHen IM and measure cortisol response - if little response we know it is Addison’s
21
Q

What is an example of cortisol levels in a typical Addison’s patient before and after synACTHen?

A
  • cortisol at 9am = 100 (270-900)
  • administer injection IM synACTHen
  • cortisol at 9:30am = 150 (>600)nM
  • ie NO response to synACTHen
22
Q

How do we treat primary adrenocortical failure?

A
  • patient needs replacement of cortisol and aldosterone
  • no need to replace adrenal sex steroids (gonads)
23
Q

What is the problem with replacing aldosterone in Addison’s disease?

A
  • problem with aldosterone is half-life is too short for safe once daily administration
  • fludrocortisone (50-100mcg daily) - longer acting than aldosterone
  • fludrocortisone is an agonist for the MR (mineralocorticoid) receptors
24
Q

What specific drugs do we give to treat primary adrenocortical failure?

A
  • fludrocortisone 50-100mcg daily (aldosterone replacement)
  • EITHER hydrocortisone three times daily (10mg + 5mg + 2.5mg) OR prednisolone 3mg daily - (cortisol replacement)
25
Q

What is congenital adrenal hyperplasia?

A

Missing enzyme needed for adrenocortical hormone synthesis

26
Q

What is the commonest cause of congenital adrenal hyperplasia?

A
  • 21-hydroxylase deficiency
  • can be complete or partial
27
Q

Which hormones will be missing in complete congenital adrenal hyperplasia: 21 hydroxylase deficiency?

A

Aldosterone and cortisol

28
Q

How long can you survive with complete congenital adrenal hyperplasia?

A

Babies present within 1-3 weeks with a salt-losing crisis (can only survive less than 24 hours)

29
Q

Which hormones will be in excess in complete congenital adrenal hyperplasia: 21 hydroxylase deficiency?

A
  • sex steroids and testosterone
  • as there is nowhere for the precursors to go - progesterone and 17-OH progesterone build up and therefore feed into the sex steroid pathway

If deficiency starts with 1, high BP reduced K+
If deficiency ends with 1, excess sex steroids

30
Q

What is the age of presentation of complete congenital adrenal hyperplasia: 21 hydroxylase deficiency?

A
  • as a neonate with a salt losing Addisonian crisis
  • before birth, the foetus gets steroids across the placenta
31
Q

What is the difference between how girls and boys present in complete congenital adrenal hyperplasia: 21 hydroxylase deficiency?

A

Girls might have ambiguous genitalia (virilised by adrenal testosterone) - but boys do not

32
Q

What happens in partial congenital adrenal hyperplasia: 21 hydroxylase deficiency?

A

There is a bit of aldosterone and cortisol to get by with

33
Q

Which hormones are deficient in partial congenital adrenal hyperplasia: 21 hydroxylase deficiency?

A

Cortisol and aldosterone

34
Q

Which hormones are in excess in partial congenital adrenal hyperplasia: 21 hydroxylase deficiency?

A

Sex steroids and testosterone

If deficiency starts with 1, high BP reduced K+
If deficiency ends with 1, excess sex steroids

35
Q

What is the age of presentation of partial congenital adrenal hyperplasia: 21 hydroxylase deficiency?

A

At any age as they survive

36
Q

What is the main problem for boys and girls with partial congenital adrenal hyperplasia: 21 hydroxylase deficiency?

A
  • girls - hirsutism and virilisation
  • boys - precocious puberty due to adrenal testosterone
37
Q

What happens if we have 11-hydroxylase deficiency?

A
  • accumulation of 11-deoxycorticosterone
  • 11-deoxycorticosterone behaves like aldosterone (mineralocorticoid)
  • in excess it can cause hypertension and hypokalaemia
38
Q

What hormones are deficient in 11-hydroxylase deficiency?

A

Aldosterone and cortisol

39
Q

What hormones are in excess in 11-hydroxylase deficiency?

A
  • sex steroids, testosterone and 11-deoxycorticosterone
  • increased precursors above block –> sex steroid arm of pathway

If deficiency starts with 1, high BP reduced K+
If deficiency ends with 1, excess sex steroids

40
Q

What problems occur in 11-hydroxylase deficiency?

A
  • virilisation (high testosterone)
  • hypertension (11-deoxycorticosterone)
  • low K+ (11-deoxycorticosterone)
41
Q

Which hormones are deficient in 17-hydroxylase deficiency?

A

Cortisol and sex steroids

42
Q

Which hormones are in excess in 17-hydroxylase deficiency?

A

Aldosterone and 11-deoxycorticosterone (mineralocorticoids)

If deficiency starts with 1, high BP reduced K+
If deficiency ends with 1, excess sex steroids

43
Q

What problems does 17-hydroxylase deficiency cause?

A
  • hypertension
  • low K+
  • sex steroid deficiency
  • cortisol deficiency (glucocorticoid deficiency = low glucose)

Year 2 - BRS (84 decks)

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