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LCRS Endo > Hypoadrenal Disorders > Flashcards

Hypoadrenal Disorders Flashcards

1
Q

what is the precursor to the steroids?

A

cholesterol

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2
Q

the 3 arms of steroid genesis?

A

aldosterone
cortisol
sex steroids

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3
Q

sources of sex hormones

A

main: gonads
secondary: adrenal cortex

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4
Q

enzymes involved in steroidogenesis?

deficiencies in

A

hydroxylases

17,21,11,18

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5
Q

methods that destroy the adrenal gland causing adrenal failure?

A

1) TB (developing world) - how Addison described it
2) autoimmune (developed world)- atrophy
3) congenital adrenal hyperplasia (overgrowth with dysfunction)–> crisis

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6
Q

manifestation of adrenocortical failure in terms of aldosterone problems

A

effects of low aldosterone:

  • hypotension (postural as well)
  • loss of salt
  • hyperkalaemia
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7
Q

additional signs of Addisons

A
  • hypoglycaemia (low glucocorticoid, cortisol mobilised glucose)
  • hyper pigmentation
  • vitiligo
  • eventual death due to severe hypotension
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8
Q

why does hyperpigmentation occur in Addisons?

A

with the excess ACTH produced as a result of low cortisol (negative feedback)

a lot of MSH (melanocyte stimulating hormone) is produced

MSH is a product along with ACTH from the breakdown of precursor POMC, that causes pigmentation

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9
Q

what should cortisol levels be normally? How does this compare to an Addison’s patient?

A

in the morning it should be highest and at night it should be lowest.
morning 9am cortisol = 270-900

An Addison’s patient will have low cortisol throughout the day.
morning 9 am cortisol= 100
ACTH remains high

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10
Q

what does vitiligo determine for the patient?

A

the adrenal failure is of autoimmune cause. Also seen with Grave’s with thyroid destruction, here melanocytes are destroyed showing an autoimmune predisposition in the patient

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11
Q

what causes the loss of salt (in urine) and therefore the hyperkalaemia?

A

low aldosterone means that sodium in not reabsorbed as a result of RAS and therefore sodium is excreted while potassium remains unexchanged.

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12
Q

what test is used to identify Addison’s?

A

short synacthen

  • 250 micrograms of synthetic ACTH administered i.m.
  • this is a large dose to induce a large response
  • cortisol response is measured: a poor response is indicative of Addisons (e.g. 100 to 150), Normally it should rise about 600
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13
Q

two types of Congenital Adrenal Hyperplasia (CAH)?

A

1) complete

2) partial

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14
Q

what are the four enzymatic deficiencies that caused CAH?

A
  • complete 21- hydroxylase deficiency (most common)
  • partial 21-hydroxylase deficiency
  • 11-hydroxylase deficiency
  • 17-hydroxylase deficiency
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15
Q

what is the most common cause of CAH?

A

complete 21-hydroxylase deficiency leading to no production of aldosterone or cortisol

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16
Q

how does hirsutism arise from complete 21-H deficiency?

A

overload of sex steroid production arm causing excess production as the other arms are useless

17
Q

what is the presentation in children with 21-H deficiency?

A
  • salt losing Addisonian crisis
  • in utero the child receives steroids from the mother
  • girls present more obvious effects that boys with ambiguous genitalia (virilisation) and may have clitormegaly.
  • children survive for less than a few weeks
18
Q

what happens in partial 21-H deficiency?

A

little amounts of aldosterone and cortisol are produced but not enough
sex steroids are still in excess

19
Q

what is the presentation of partial deficiency of 21-H?

A

at any age, as they do survive

in later life hirsutism and virilisation for girls and precocious (early) puberty in boys

20
Q

what are the symptoms of partial 21-H deficiency?

A 
acne
facial hirsutism 
small breasts
clitoral enlargement 
heavy arms/legs
21
Q

what occurs in the steroidogenesis pathway with 11-H deficiency

A

accumulation of the precursors of the products made by 11-H i.e. 11-deoxycorticosterone and 11- deoxycortisol, in the z.glomerulosa.

22
Q

what are the consequences of 11-deoxycortisone accumulation due to 11-beta hydroxylase deficiency?

A

behaves like aldosterone so can cause hypertension (acts as weak mineralocorticoid)

and hypokalaemia (excess potassium excretion with aggravated RAS)

sex hormone shunting

23
Q

what are the biochemical markers of 11-beta Hydroxylase deficiency?

A
  • low cortisol and aldosterone
  • excess sex steroids (sex steroid shunting)
    and 11-deoxycorticosterone leads to virilisation, hypertension and hypokalaemia
24
Q

what are the biochemical markers of 17-alpha Hydroxylase deficiency?

A

-low cortisol and SEX steroids
(17 OH progesterone precursor is not produced, 17 OH goes into sex steroids arm)
- high aldosterone: as progesterone remains only to make aldosterone in excess

25
Q

what are the effects of 17-H deficiency?

A
  • hypertension (excess aldosterone and 11-deoxycorticosterone)
  • hypokalaemia
  • sex steroid deficiency –> delayed puberty
  • glucocorticoid deficiency (low cortisol) due to shunting into mineralocorticoids
26
Q

what would a blood test for Addisons’ Disease show?

A
  • low sodium (leads to hypotension)
  • high potassium (due to low aldosterone–> low sodium retention, low potassium removal)
  • ACTH and cortisol measurement
27
Q

how can you diagnose Addisons with a short synacthen test?

A

if cortisol remains the same or barely changes

28
Q

what leads to increased pigmentation?

A

POMC–> ACTH + MSH + endorphins and enkaphalins

continuous production of ACTH due to lack of negative feedback means MSH is made along side it continuously

MSH increase stimulation to melanocytes

29
Q

what is the treatment for Addison’s?

A
  • lifelong hydrocortisone
  • steroid bracelet
  • double dosage when ill
30
Q

what is the treatment for Addisonian crisis?

A
  • 0.9 saline (hyponatraemia)
  • IV dextrose (hypoglycaemia–>cardiac arrest) and hydrocortisone
  • IV insulin
31
Q

what are the clinical features of Addisons?

A

low sodium
high potassium
low aldosterone
low cortisol

32
Q

what are the effects of 21 hydroxylase deficiency?

A
  • no aldosterone or cortisol
  • sex steroid shunting (therefore ambiguous genitalia in neonates)
  • Addisonian crisis (due to low aldosterone when suddenly stopping treatment, CAH or not doubling dose when ill)
33
Q

what is looked at to detect 21 hydroxylase deficiency?

A

look for build up of 17 hydroxyprogesterone

34
Q

what are the effects of partial 21 hydroxylase deficiency?

A
  • there is some enzymatic activity
  • therefore some aldosterone and some cortisol
  • no Addisons crisis
  • signs seen in early puberty

LCRS Endo (18 decks)

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