Endocrinology - Adrenal, Diabetes Flashcards
(123 cards)
where specifically does each zone of the adrenal cortex contain?
- Outer zone glomerulsa - aldosterone
- middle zona fasciulata - cortisol
- inner zone reticularis - androgens
- GFR - ACR
where in the adrenal glands is epinephrine produced?
chromaffin cells in the adrenal medulla
what is the function of mineralocorticoids function ?
aldosterone normally increase sodium absorption and K+/H+ excretion so high levels cause hypertension, hypokalemia, and alkalosis.
what is the function of glucocorticoids?
- cortisol stimulates lipolysis
- release of amino acid from muscles
- liver glucogenesis
- inhibits inflammatory process
- Inhibits T-cells and associated DTH and cell-mediated immunity\
- excess cortisol can stimulate mineralocorticoids and androgen receptors with a similar appearance to aldosterone excess (HTN, hypokalemia, alkalosis)
- It does not bind to androgen receptors.
what are the androgens produced by the adrenals?
DHEA and small amounts of testosterone.
what is the effect of excess adrenal androgens in a woman?
- during gestation - ambiguous genitalia
- Postnatally - excess hair and abnormal menses
Describe signs and symptoms of Cushing syndrome?
excessive adrenal glucocorticoid production causing:
- proximal muscle weakness and fatigue
- amenorrhea, hirsutism, acne
- easy bruising
- emotional liability/frank psychosis
what are the physical exam findings of Cushing syndrome?
facial plethora (redness of face/fullness due to increased blood flow)
thin skin with pink to purple striae
cervicodorsal fat pad
truncal obesity
moon facies
what are the comorbid conditions associated with Cushing syndrome?
DM2 and osteoperosis
what are the causes of cushing syndrome from most to least frequent?
- iatrogenic cortisol adminsitration
- ACTH - secretuing pituitary adenoma (cushing disease)
- ectopic ACTH secretuing tumor: (bronchogenic, pancreatic, thymic (if age>60), SCLC
- bilateral adrenal hyperplasia
- adrenal tumors
what would you expect to see on a BMP with cushing syndrome?
hypokalemia and metabolic alkalosis
what can mimic the phenotypic features of cushing’s syndrome? why is this important?
- obesity, alcoholism, and depression can mimic
- important as they can result in slightly increased 24-hour urine cortisol and/or abnormal low-dose suppression test
- this is called pseudo-cushing’s.
what does ACTH do again?
increases cortisol, androgens, and mineralocorticoids.
what is the difference between Cushing disease and Cushing syndrome?
- Cushing disease is a disease in the head, caused by a pituitary microadenoma which has increased ACTH stimulating the production of adrenal DHEA.
- Females can present with virilization (hirsitusim and acne)
what endocrinology labs would you expect to see with an adrenal adenoma that is producing cortisol?
ACTH and DHEA would be low.
what are the initial tests to get for Cushing syndrome workup?
- 24 hour urine free cortisol
- late-night salivary cortisol and/or
- low dose dexamethasone suppression test to confirm excess cortisol
- abnormal tests should be confirmed at least once.
- note that urinary cortisol reflects plasma free cortisol levels
how do you identify pseduo-Cushing’s?
elevated cortisol levels (urine) with suppression with low dose dexamethasone suppression of cortisol
what is your next step in working up Cushing’s syndrome if you have elevated cortisol with failure to suppress cortisol with low dose dexamethasone test?
- identify if this is ACTH dependent or ACTH independent disease by measuring ACTH.
- Normally, a high cortisol completely suppresses ACTH production
- Any measurable ACTH indicates ACTH dependent Cushing syndrome (Cushing disease or ectopic ACTH production)
- ACTH to low to be measured indicates ACTH independent Cushing syndrome - (nonpituitary adrenal hyperplasia or adrenal mass)
what if your next step if you have a high urinary cortisol, measurable ACTH?
- this is an ACTH dependent Cushing syndrome so either pituitary tumor (Cushing disease) or ectopic ACTH secreting tumor.
- Next step is to image the pituitary with a gadolinium-contrasted MRI
- Can also image chest/abdomen with high res CT.
what is the next step if you have high cortisol, low/unmeasurable ACTH ?
- this is likely ACTH independent cushing syndrome from an adrenal tumor (adenoma or carcinoma)
- Would measure DHEA and testosterone concentrations
- Adrenal adenomas have low ACTH and modest DHEA levels
- carcinomas have low ACTH and high DHEA and urine 17 ketosteroids.
- adrenal tumors do not usually suppress cortisol production in response to high dose dexamethasone test.
what is the difference between primary and secondary adrenal insufficiency in terms of labs?
- primary (abnormal cosyntropin stim, high ACTH, low aldosterone, hyponatremia, hyperkalemia,
- secondary (abnormal cosyntropin stim, low ACTH production by pituitary or withdrawal of glucocorticoids, normal aldosterone)
- all adrenal insufficiency does not respond to ACTH stimulation
why do you have hyperkalemia with primary adrenal insufficiency and not secondary?
primary AI would affect both the zona glomerulosa and zona fasiculata causing a hyperreninemic hypoaldosteronism.
what labs do you get to test for adrenal insufficiency?
- baseline cortisol, serum aldosterone, ACTH
- Cosyntropin stimulation test 0,30.60.
- If ACTH not >18-20, diagnostic.
what is the treatment for AI?
corticosteroids and mineralcorticoids like fludrocortisone