Adrenals Flashcards
What is the cortex to medulla ratio?
90%:`10%
What are the parts of the cortex? What do they do?
- zona glomerulosa (secrete mineralocorticoids - aldosterone)
- zona fasciculus (glucocorticoids - cortisol)
- zona reticularis (androgens) (and glucocorticoids)
What cells are contained in the medulla? What do they do?
Chromaffin cells - release catecholamines (adrenaline and noradrenaline)
What are the differences in shape between the right and left adrenal glands?
Right - pyramidal
Left - crescentic
How does blood supply get to the adrenal glands?
- subscapular plexus -> vessels -> fenestrated sinusoids
- most cells 1/2 away from vascular endothelial cell
What initiates steroid production in the cortex?
Cholesterol uptake and conversion
What does hyperaldosteronism cause?
Low potassium, high blood pressure and alkalosis, suppressed renin activity
(high aldosterone)
(Conn’s syndrome)
How do you diagnosis hyperaldosteronism?
- aldosterone:renin ratio
- CT adrenal
- adrenal venous sampling
What is the mineralocorticoid receptor?
- aldosterone binds to them
- expressed in the nucleus
- cortisol also binds but cortisone inactivates unless overwhelming conditions
What are the functions of aldosterone?
- stimulates Na/K ATPase and increases expression
- inserts additional ENacs
- stimulates H+ ATPase channel
(THEREFORE when excess loss of H+ = metabolic alkalosis and K+ loss balancing intake of Na+)
What is Liddle’s syndrome?
Increased expression of ENac = hypertension, hypokalemia, metabolic alkalosis
What are the function of glucocorticoids?
Deal with stress:
starvation -> breakdown fuels
infection -> immunosuppression
Hypotension -> increase BP
What are the causes of Cushing’s?
- iatrogenic
- corticotroph adenoma of the pituitary!!!
- bilateral adrenal hyperplasia
- cortisol secreting adrenal adenoma
How is Cushing’s diagnosed?
- dexamethasone suppression test overnight
- 24 hour urine free cortisol
- MRI pituitary
- CT adrenals
How do you treat Cushing’s?
PITUITARY: transphenoidal surgery, external beam radiotherapy, stereotactic radiosurgery
ADRENAL: adrenalectomy, etomidate
Symptoms of Addison’s disease?
fatigue, weakness, myalgia, anorexia, weight loss, hyperpigmentation
Causes of primary adrenal failure?
Autoimmune
TB
What is Addison’s disease?
when something stressful happens and cannot respond to it = low bp, sodium, potassium, glucose
How do you diagnose Addison’s?
Low 9am cortisol
high ACTH
How do you treat Addison’s?
- replace steroid with hydrocortisone and fludrocortisone (mineralocorticoid)
- IV fluid resuscitation
- IM hydrocortisone
What is congenital adrenal hyperplasia?
Defect in conversion to aldosterone and cortisol and excess ACTH secreted as no negative feedback
- stimulate cholesterol uptake in adrenal gland which is converted to cortisol then into testosterone
What kind of stress do stress hormones respond to?
Starvation
Infection
Severe volume loss
