Adrenal Disorders Flashcards
Where are the adrenal glands?
Immediately in front of the kidneys
What is produced by the adrenal medulla?
Noradrenaline and adrenaline produced and secreted
What is produced by the adrenal cortex?
- Mineralcorticoids - aldosterone (0.15mg/day)
- Glucocorticoids
- cortisol (hydrocortisone - 15-20mg/day)
- corticosterone (3mg/day)
How is cortisol produced?
- Corticotrophin releasing hormone is release from the hypothalamus
- CRH stimulates the pituitary to release adrenocorticotrophin releasing hormone
- ACTH acts in the adrenal gland to produce cortisol
Short loop inhibition - negative feedback to pituitary
Long loop inhibition - negative feedback to hypothalamus
What does aldosterone do?
- Increase resorption if water
- Increase resorption if Na
- Increase renal excretion if K
What are the physiological effects of glucocorticoids?
Metabolic and systemic effects
- decreased glucose uptake and utilisation
- increased gluconeogensis
- increased protein breakdown and decreased protein synthesis
- increased fat breakdown in adipose tissue
- anti-inflammatory and immunosuppressive effects
- early - inhibit initial redness, heat, pain and swelling
- late - inhibit wound healing and repair
- osteoclast - digest bone matrix
- osteoblast - lay down bone matrix
- mineralcorticoid activity
What is Cushing syndrome?
Adrenocortical hyperfunction - symptoms and signs associated with prolonged exposure to inappropriately elevated plasma corticosteroid levels
What causes Cushing syndrome?
- Excessive endogenous cortisol production - adrenal tumour
- Administration of glucocorticoids
What are the signs and symptoms of Cushing syndrome?
- Moon face
- Central obesity
- Buffalo hump
- Bruising and muscular weakness
- Acne and hirsuitism
- Osteoporosis
- Hypertension
- Glucose intolerance
- Psychological difficulties
How would you diagnose Cushing syndrome?
- Raised midnight plasma cortisol and loss of diurnal rhythm
- Raised urinary and salivary free cortisol
- Dexamethasone suppression test - no decrease in cortisol levels
How would you treat Cushing syndrome?
- Surgery
- Irradiation
- Metyrapone
- inhibits production of cortisol
- dose 0.25-6g daily in divided doses
- response monitored by plasma cortisol levels
What is addisons disease?
Insufficient production of cortisol often accompanied by aldosterone deficiency
What causes addisons disease?
- Primary adrenal insufficiency - autoimmune adrenalitis - IS attacks adrenal cells
- Secondary adrenal insufficiency - pituitary or hypothalamic disorder
What are the signs and symptoms of addisons disease?
- Fatigue
- Weakness
- Weight loss
- Anorexia
- Hypotension
- GI disturbances
- Hyperpigmentation of the skin
How would you diagnose Addisons disease?
- Low cortisol levels that fail to respond to synacthen test
- synacthen is a ACTH analogue
- failure of plasma conc to rise after administration - adrenal insufficiency
- Hyponatraemia and hyperkalameia
- lack of aldosterone
