ED Flashcards
Which hormone disorders can be a result of the gland itself?
→Graves disease
→Hashimoto
What disorders can be a result of adrenal hyperfunction?
→Excess cortisol (Cushing’s syndrome)
→Excess aldosterone (e.g. Conn’s syndrome)
→Adrenal insufficiency
Hypocortisolism
Lack of aldosterone and cortisol (Addison’s)
What is Conn’s syndrome?
→Aldosterone excess
primary hyperaldosteronism
→adrenal gland itself producing excess
What is Cushing’s syndrome?
→Cortisol excess
What is aldosterone secretion activated by?
→RAAS
→Increased plasma [K+]
What is RAAS activated by?
→Reduced renal perfusion
→Increased sympathetic activity
→Interpreted as fall in blood volume
What is useful in diagnosing primary hyperaldosteronism?
→plasma aldosterone/renin ratio
What are some roles of cortisol?
→Preserves plasma glucose
→promotes insulin resistance in muscles
→Promotes lipolysis, gluconeogenesis
What are some effects of excess cortisol?
→hyperglycemia,
→increased adiposity,
→hypertension,
→muscle wasting
What rises in absence of cortisol?
→ADH
What are the most common causes of Cushing’s syndrome?
→Exogenous glucocorticoids activate cortisol receptor
→Adrenal cortex atrophies with lack of ACTH stimulation
→Several days may be required for adrenal to become responsive to ACTH again
How is Cushing’s disease diagnosed?
→dexamethasone test
What is the dexamethasone test?
→After a dose of dexamethasone, cortisol levels often stay very high in people who have Cushing’s syndrome
In adrenal tumour what will the plasma ACTH be after dexamethasone test?
→low
In ectopic ACTH what would the level of ACTH be after dexamethsasone?
→very high
What is primary adrenal insufficiency?
→Addison’s disease- destruction of adrenal cortex
→Insufficient cortisol and aldosterone
What is secondary adrenal insufficiency?
→Pituitary or hypothalamic disease
→Insufficient cortisol
What is the primary stimulator for ADH?
→osmolarity
What are the clinical features of Addison’s?
→Hypotension →Plasma [Na+]: normal to low →Hyponatremia- increased ADH →Plasma [K+]: normal to high →High ACTH →Elevated plasma renin
Why is there hyperpigmentation in Addison’s?
→ACTH reacts with melanocytes receptors
What are the hallmarks of Addison’s?
→high ACTH
→low cortisol
What is used for ACTH testing?
→Synacthen
→Assess ability of adrenal to produce cortisol in response to ACTH
What is involved in the 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
What is involved in the Synacthen long 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
