endocrine disorders Flashcards
adrenal steroids
adrenal steroids:
mineralocorticoids
glucocorticoids
adrenal androgens
adrenal steroids
adrenal steroids:
mineralocorticoids
glucocorticoids
adrenal androgens
disorders of adrenocortical function
adrenal hyperfunction:
- excess cortisol = cushings syndrome
- excess aldosterone = Conn’s syndrome
adrenal insufficiency:
- hypocortisolism
- lack of aldosterone and cortisol
describe adrenocortical excess
aldosterone excess:
- conn’s syndrome (primary hyperaldosteronism)
cortisol excess:
- Cushing’s syndrome (may be primary or secondary)
describe control of aldosterone secretion
activated by:
RAAS and increased plasma
RAAS is activated by:
- reduced renal perfusion
- increased sympathetic activity
both interpreted as a fall in blood volume
plasma aldosterone/renin ratio is useful in diagnosis of primary hyperaldosteronism
source of excess aldosterone is adrenal
what’s the most common cause of Cushing’s syndrome
iatrogenic
- exogenous glucocorticoids activate cortisol receptor
- at high doses will shut down HPA
- adrenal cortex atrophies with lack of ACTH stimulation
- several days may be required for adrenal to become responsiveness to ACTH again
what is Cushing;s disease due to
ACTH secreting pituitary adenoma.
Cushing’s syndrome may also be due to ectopic ACTH source
describe adrenal insufficiency
primary:
- addison’s disease
- insufficient cortisol and aldosterone
secondary:
- pituitary or hypothalamic disease
- insufficient cortisol
describe clinical features of Addison’s
primary adrenal insufficiency:
- hypotension
- plasma: normal to low
- plasma: normal to high
- High ACTH
- elevated plasma renin
may be unmasked by significant stress or illness
shock, hypotension, volume depletion
Addison’s disease 2
progressive, can lead to adrenal crisis = fatal if not treated
hallmark is high ACTH, low cortisol
dynamic test can aid diagnosis: assess ability of adrenal to produce cortisol in response to ACTH
describe ACTH stimulation test
- assess ability of adrenal to produce cortisol in response to ACTH
Short synacthen test
Measure baseline cortisol (9am) and 30 min after 250 µg synacthen (synthetic ACTH) i.m.
Adrenal insufficiency is excluded by an increase in cortisol of >200 nmol/L and/or a 30 min value >550
Long synacthen test
Adrenal cortex ‘shuts down’ in absence of stimulation by ACTH – time needed to regain responsiveness
3-day stimulation with synacthen
In secondary (but not primary) adrenal insufficiency cortisol increases by >200 nmol/L over baseline
Long test not often necessary since ACTH assay can distinguish
disorders of adrenocortical function
adrenal hyperfunction:
- excess cortisol = cushings syndrome
- excess aldosterone = Conn’s syndrome
adrenal insufficiency:
- hypocortisolism
- lack of aldosterone and cortisol
describe adrenocortical excess
aldosterone excess:
- conn’s syndrome (primary hyperaldosteronism)
cortisol excess:
- Cushing’s syndrome (may be primary or secondary)
describe control of aldosterone secretion
activated by:
RAAS and increased plasma
RAAS is activated by:
- reduced renal perfusion
- increased sympathetic activity
both interpreted as a fall in blood volume
