Endocrine: adrenal medulla and cortex Flashcards
What is the primary hormone deficiency in Addison’s disease, and how does it manifest clinically?
CORTISOL AND ALDOSTERONE
Why does secondary adrenal insufficiency not typically result in hyperkalemia?
Aldosterone levels are preserved
since it is regulated by RAAS and not by ACTH which is deficient in secondary adrenal insufficiency
How does the ACTH stimulation test differentiate primary from secondary adrenal insufficiency?
Suboptimal cortisol response in primary; normal in secondary.
What biochemical feature distinguishes pheochromocytoma from other causes of hypertension?
elevated plasma or urinary metanephrines
metabolites of catecholamines that are overproduced in pheochromocytoma
How does Conn’s syndrome (primary hyperaldosteronism) lead to metabolic alkalosis?
Excess aldosterone increases sodium reabsorption and potassium/hydrogen ion excretion.
the resulting hypokalemia and loss of hydrogen ion shifts pH towards alkalosis
Why does congenital adrenal hyperplasia (CAH) cause virilization in females?
excess androgen production
deficiency in cortisol synthesis leads to increased ACTH stimulation = converts precursors to androgen
What imaging modality is preferred for localizing an adrenal incidentaloma?
CT/MRI
What is the most common cause of Cushing’s syndrome?
EXOGENOUS glucocorticoid use (iatrogenic cushing’s syndrome)
How can adrenal insufficiency lead to hyponatremia?
Lack of aldosterone causes sodium loss; cortisol deficiency leads to inappropriate ADH secretion.
Hallmark feature of adrenal crisis
HYPOTENSION unresponsive to fluids
Lack of cortisol impairs vascular tone and stress response, necessitating immediate steroid replacement.
How does a 21-hydroxylase deficiency impact adrenal hormone synthesis?
overproduction of 17-hydroxyprogesterone and androgen imparing cortisol and aldosterone production
Why is hyperpigmentation observed in primary adrenal insufficiency but not secondary?
Elevated ACTH levels in primary stimulate melanocyte activity
How can you differentiate adrenal Cushing’s syndrome from pituitary Cushing’s disease?
LOW ACTH levels in ADRENAL cushing’s syndrome
What electrolyte abnormalities are expected in pheochromocytoma?
hyperglycemia
hypercalcemia
What is the significance of a “dex suppression test” in hypercortisolism evaluation?
Failure to suppress cortisol suggests Cushing’s syndrome.
Normal feedback mechanisms are disrupted in endogenous cortisol overproduction.
