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LCRS Year 2 - Endocrinology > Hypoadrenal Disorders > Flashcards

Hypoadrenal Disorders Flashcards

1
Q

What two hormones are involved in the hypothalamo-pituitary-adrenal axis?

A

CRH - Corticotrophin releasing hormone

ACTH - AdrenoCorticoTrophic Hormone (corticotrophin)

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2
Q

Why are some of the ant. pituitary called “trophins”?

A

Cause growth of the gland

e.g. corticotrophin causes adrenal glands to grow and release cortisol

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3
Q

What is the precursor molecule of all steroids?

A

Cholesterol

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4
Q

What is the first molecule produced after enzyme action on cholesterol?

A

Pregnenolone

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5
Q

What steroid hormones do the zona glomerulosa, zona fasciculata, testes/ovaries make?

A

Zona glomerulosa - Aldosterone

Zona fasciculata - Cortisol

Testes/ovaries - sex steroids (testosterone, androgens, oestrogens)

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6
Q

What is the crucial enzyme type throughout steroid synthesis and why do they have different numbers?

A

Hydroxylases

- Numbered to reflect the carbon in the steroid they act on

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7
Q

Recreate, on paper, the pathway of steroid synthesis including aldosterone, cortisol and sex steroids. Include the number of the hydroxylase enzyme involved in each step. (Found in PPT)

A

Cholesterol to progesterone (general first step)

Progesterone –21–> 11 deoxycorticosterone –11–> corticosterone –18–> aldosterone

Progesterone –17–> 17 OH progesterone –21–> 11 deoxycortisol –11–> cortisol

Progesterone –17–> 17 OH progesterone –> sex steroids

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8
Q

What are the 3 causes of adrenocortical failure?

A

Addison’s disease is destruction of adrenal glands

  • Tuberculous Addison’s disease
  • Autoimmune Addison’s disease
  • Congenital adrenal hyperplasia (hydroxylase enzymes missing so low cortisol, tons of ACTH make adrenal glands grow and grow so born with enormous adrenal glands that can’t make cortisol)
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9
Q

What are the consequences of adrenocortical failure?

A
  • Fall in blood pressure
  • Loss of salt in the urine
  • Increased plasma potassium with low sodium
  • Fall in glucose due to glucocorticoid deficiency
  • High ACTH resulting in increased pigmentation
  • Eventual death due to severe hypotension
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10
Q

Why does increased pigmentation occur in hypoadrenalism?

A

Pro-hormone for ACTH is POMC

  • Pro-opio melanocortin
  • Synthesised in pituitary and broken down into ACTH and MSH (melanocyte stimulating hormone) and a bunch of other stuff
  • MSH is the key here
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11
Q

What other diseases can come with autoimmune Addison’s disease?

A

Autoimmune diseases go together

  • e.g. autoimmune thyroid disease WITH autoimmune adrenal disease
  • vitiligo (melanocyte destruction), loss of pigmentation in patches
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12
Q

What’s the first step in diagnosing Addison’s disease?

A

First step is to actually THINK of it

- listen to the patient and have it in the back of your mind

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13
Q

What are the tests for Addition’s disease?

A

9am cortisol = low (should be high)
ACTH = high (while cortisol is low)

Short synACTHen test

  • given 250 micrograms synacthen intramuscularly
  • measure cortisol response, should be high and rapid response, if not, Addison’s
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14
Q

What are the cortisol levels in a typical Addison’s patient at 9am and after IM synACTHen as well as normal parameters?

A

Cortisol at 9am = 100 (270-900)

Administer synACTHen intramuscularly

Cortisol at 9:30am = 150 (>600)

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15
Q

What is the commonest cause of congenital adrenal hyperplasia?

A

21-hydroxylase deficiency

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16
Q

What are the two types of congenital adrenal hyperplasia (CAH)?

A

Complete

Partial

17
Q

In complete 21-hydroxylase deficiency, which hormones will be totally absent, how long can you survive, and which hormones will be in excess?

A
  • Aldosterone and cortisol
  • Less than 24 hours (out of womb)
  • Sex steroids and testosterone
18
Q

What is the age of presentation of complete 21 hydroxylase deficiency and what happens in girls who have this?

A

As a neonate with a salt-losing Addisonian crisis
- Before birth, (while in utero), foetus gets steroids across placenta normally, they’re born and lose that source of hormone and go straight into Addisonian crisis

Girls might have ambiguous genitalia (virilised by adrenal testosterone), very worrying as sign of complete 21 H deficiency, must be treated straight away before they go into Addisonian crisi

19
Q

In partial 21-hydroxylase deficiency, which hormones are deficient, which hormones are in excess, and what age will they present?

A
  • Cortisol and aldosterone
  • Sex steroids and testosterone
  • Any age as they will survive birth
20
Q

Why does sex steroid and testosterone production get boosted in both complete and partial 21-hydroxylase deficiency?

A

Again, back to the diagram for steroid synthesis

  • if 21-H is only partially working, cortisol levels will be low so more 17-OH prog is produced to try and make more cortisol, this boosts sex hormone/testosterone production above normal while getting cortisol levels to somewhere near normal
  • if 21-H is not working at all, there is no cortisol so even more 17-OH prog is made with no cortisol production and huge sex steroid/testosterone production
21
Q

What are the main problems with partial 21-hydroxylase deficiency in boys and girls and when do these problems present?

A
  • Hirsutism (hairiness) and virilisation in girls
  • Precocious puberty in boys

All due to adrenal testosterone

22
Q

What changes take place in the adrenal glands of a partially 21-H deficient patient and why?

A

Hyperplasia (large growth) of adrenal glands

- never enough cortisol to suppress ACTH release via negative feedback thus constant stimulation of adrenal gland growth

23
Q

In 11-hydroxylase deficiency, which steroid hormones are deficient and which hormones are in excess?

A

Consult the diagram (memorise it)

  • Cortisol and aldosterone
  • Sex steroids, testosterone and 11-deoxycorticosterone
24
Q

Why are there aldosterone effects seen in 11-hydroxylase deficient children despite their inability to make aldosterone?

A

11-deoxycorticosterone is the steroid created after progesterone two steps before aldosterone production
- This steroid can bind to aldosterone receptors and so stimulates effects normally produced by aldosterone

25
Q

Keeping in mind 11-deoxycorticosterone behaves like aldosterone, what does it cause in excess?

A

Hypertension

Hypokalaemia

26
Q

What problems are caused by 11-hydroxylase deficiency?

A
  • Virilisation
  • Hypertension
  • Hypokalaemia
27
Q

Patients with 11-hydroxylase deficiency have symptoms very similar to Conn’s syndrome, excessive aldosterone. Why is this NOT Conn’s syndrome?

A

No aldosterone, Conn’s is defined by the effects being caused by excessive aldosterone but 11-H deficient patients won’t have any aldosterone at all

28
Q

In 17-hydroxylase deficiency, which hormones are deficient?

A

Cortisol

Sex steroids/testosterone

29
Q

In 17-hydroxylase deficiency, which hormones are in excess?

A

11-deoxycorticosterone
Aldosterone
(mineralocorticoids, like both of these are)

30
Q

What are the problems in 17-hydroxylase deficiency?

A
  • Hypertension
  • Hypokalaemia
  • Sex steroid deficiency
  • Glucocorticoid deficiency (low glucose)
31
Q

What signs will the deficiency of sex steroid and testosterone in 17-hydroxylase deficiency show?

A

These children will never go through puberty

  • always prepubescent
  • a bit tired
  • all of testes/ovaries and adrenals missing 17-hydroxylase enzyme

Present at 7+ when their friends all start to continue to grow and develop while they don’t

32
Q

How can the sex steroid deficiency in 17-hydroxylase deficiency be corrected?

A

Hormone replacement therapy for whatever hormones they’re missing corrects it relatively easily

LCRS Year 2 - Endocrinology (21 decks)

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