Endo 3C Flashcards
What is Cushing’s disease?
Excess glucocorticoid due to a pituitary adenoma
It is ACTH dependent
What is ectopic ACTH syndrome?
A nonpituitary carcinoma that over secretes ACTH
It is not ACTH dependent
What does it mean to have an ACTH dependent disease?
There is also adrenal androgen excess
In females, causes hirsutism and acne
Can cause hyperpigmentation
Is an adrenal tumor ACTH dependent?
No
What can happen with chronic glucocorticoid therapy?
ACTH independent glucocorticoid excess –> leads to overstimulation of the receptors
What is seen clinically with excess glucocorticoid?
"Central" Obesity Muscle weakness Thinning skin Hyperglycemia HTN H-O-kalemia Metabolic alkalosis Depression Insomnia Psychosis Mania Reduced reproductive fxn Poluria Polydipsia Osteoporosis Glaucoma Cataracts Reduced linear growth in children
What is the urinary free cortisol after dexamethasone suppression test?
Administer exogenous glucocorticoid (dexamethasone) to induce negative feedback on the anterior pituitary
How to interpret results of urinary free cortisol after dexamethasone suppression test?
If ACTH independent, ACTH decreases
If ACTH dependent, ACTH increases
How to interpret high dose dexamethasone suppression test?
Give high dose dexamethasone.
If ACTH secreting corticotroph adenoma = suppression is seen
If ectopic ACTH carcinoma = no suppression
How can excess glucocorticoid be treated?
Remove tumor, give ketoconazole, give metyrapone
What can cause mineralocorticoid excess?
ZG tumor aka Conn’s syndrome
excess cortisol
excess 11DOC
What is seen clinically in mineralocorticoid excess? (hint: triad of effects)
HTN
hypokalemia
metabolic alkalosis
Cardiac remodeling
What diagnostic test can determine mineralocorticoid excess?
Look at aldo/renin ratio
High aldo + low renin = Conn’s
Normal ratio with low total concentrations = excess cortisol or excess 11DOC
How can mineralocorticoid excess be treated?
Remove tumor Block synthesis of aldosterone Block MR (spironolactone)
What are exogenous glucocorticoids used for?
Reduce inflammation, immunosuppressant, treat deficiency (Addison’s)
Damage of what part of the bone can lead to short bone in children?
The epiphyseal plate
What part of the bone gives bone it’s strength?
Compact bone aka cortical bone
What are the main steps in bone formation?
Osteoblasts secrete Osteoid (organic matrix) which mineralizes with Ca and PO4 to form bone
What are the main steps in bone resorption?
Osteoclasts secrete proteases and H+ to degrade bone and release Ca and PO4
How does phosphate affect free calcium?
Binds and reduces blood levels
How does alkalosis affect free calcium?
Lowers free calcium
Where is parathyroid hormone found?
In chief cells within the parathyroid gland
How does PTH affect Ca and PO4? What receptor does it bind?
Increases plasma Ca2+ and reduces plasma PO4
PTHR-1
What does constant high [PTH] cause in bone? Intermittent normal [PTH]?
High = resorption
Normal = formation
What does PTH do in the kidney?
Increase Ca2+ reabsorption
excretes PO
activates vitamin D
How is PTH release controlled?
Calcium sensing receptor
What causes reduced PTH release?
High Ca2+
High Vit D
What causes increased PTH release?
Low Ca2+
High PO4
Where is calcitonin made?
In C cells within the thyroid gland
How does calcitonin affect Ca2+ and PO4?
Reduces Ca2+
reduces PO4
What does calcitonin do in bone?
Inhibit resorption in osteoclasts (binds CTR)
