Adrenal Cortex Flashcards
(25 cards)
Consequences of obsence of the mineralocorticoid, aldosterone (zona glomerulosa)
- loss Na+
- decrease volume ECF
- low blood pressure
- circulatory shock
- death
Consequences of absence of glucocorticoid, cortisol (zona fasciculata, zona reticularis)
- circulatory failure
- inability to mobilize energy sources from glycogen or fat
Why absence of cortisol results in circulatory failure?
Cathecolamines need cortisol to work - exert vasoconstriction
Implications of inability to mobilize energy resources from glycogen and fat in absence of cortisol context
- Normal conditions - not life-threatening
- Stress - fasting - fatal hypoglycemia
If there is a problem with anterior pituituary secretion, whicht adrenal cortex hormone is not affected on its production? What stimulus controls it?
- Aldosterone
- Angiontesin II, k+
Only negative feedback for ACTH on pituitary
Cortisol
*Other adrenals hormones don’t make (-) feedback
Index of all androgens, adrenal and testicular? index of androgen production by the adrenals?
- Urinary 17-ketosteroids
- Sulfated form of 17-ketosteroids
What is the weak mineralocorticoid that can keep you alive without hypothetical 11 B-OH deficiency?
11-Deoxycorticosterone
What mechanisms does cortisol use to raise blood glucose?
- counteracts insulin’s actions in most tissues
- gluconeogenesis
- permissive actions for glucagon and cathecolamines
What change in the body you may see when excessive secretion of ACTH (primary adrenal insufficiency as example)? Why?
- darkening of the skin
- alfa-MSH sequence within ACTH, B-MSH activity of B-lipoprotein
How does the aldosterone mediate the secretion of K+ at principal cell in collecting duct?
Reabsorption of Na ▶️ (-) luminal potential ▶️ K+ excretion
About acid-base estate, what can the excess and insufficient of aldosterone produce and why?
- excess: alkalosis
- deficiency: acidosis (type IV RTA)
Why a volume-depleted states tend to produce alkalosis?
⬆️ aldosterone (compensate volume ⬇️) ▶️ ⬆️ excretion H+ and ⬆️ plasma HCO3
Hypercortisolism due to an adenoma of the anterior pituitary (microadenoma)
Cushing disease
*cushing syndrome is hypercortisolism regardless origin (including chronic corticoid therapy)
In what cases could you have false positive of the 1-mg overnight dexamethasone suppression test?
Depression or alcoholism
If you are sure about a hypercortisolism, and got a high ACTH level, how can you distinguish pituitary vs ectopic source?
High-dose dexamethasone suppression test
- pituitary source: cortisol decreases
- ectopic ACTH (adrenal tumor also): cortisol not suppressed
What test do you use to diagnose adrenal insufficiency (Addison disease)?
ACTH stimulation test
Clinical presentation of adrenal adenoma, what is the disease?
Unilateral, only cortisol secretes, ⬇️ adrenal androgen and deoxycorticosterone (no hirsutism)
- primary hypercortisolism
What do you suspect if in context of primary hypercortisolism there is an androgen and mineralocorticoid excess?
Adrenal Carcinoma
Most common cause of secondary hypocortisolism
Sudden withdrawal of exogenous glucocorticoid therapy
What test can you make if suspect hypocortisolism (adrenal insufficiency) but the ACTH stimulation test was relatively normal?
Insulin infusion
How do you distinguish a secondary from primary (Addison’s) adrenal insufficiency?
ACTH levels
- ⬆️: primary (Addison’s disease)
- ⬇️: secondary
Diagnosis if cortisol not suppressed with 1 mg overnight dexamethasone test and high dose dexamethasone ACTH suppressed
Secondary hypercortisolism - pituitary source (Cushing disease)
How do you distinguish a primary vs secondary hyperaldosteronism?
- primary (conn’s syndrome): ⬇️ renin, ⬆️ aldosterone
- secondary: ⬆️ renin, ⬆️ aldosterone
