Flashcards in Disorders of the Adrenal Gland Deck (59)
What does the adrenal gland produce?
Steroids (glucocorticoids, mineralcorticoids and androgens/DHEA) and catecholamines
What is produced in the zona glomerulosa?
Mineralocorticoids (aldosterone-regulate salt balance and blood vol)
What is produced in the zona fasciculata?
Glucocorticoids (cortisol-increase blood glucose, metabolism)
What is produced in the zona reticularis?
Androgens (DHEA-converted into testosterone, DHT and estradiol)
What is produced in the adrenal medulla?
Catecholamines (increase BP, respiration, HR, constrict BF to GI tract)
Functions of cortisol
Stimulate gluconeogenesis (increase blood glucose)
Decrease glucose uptake by tissues
Promote anti-inflammatory effects
Reduce bone formation
Increase proteolysis in muscle
Maintains normal BP
Decrease intestinal and renal Ca absorption, decreasing plasma Ca
Inhibit collagen formation
When is cortisol release the highest?
What does Cushing's syndrome result from?
Prolonged exposure to excess glucocorticoids and androgens
Main features of Cushing's syndrome
Adrenal androgen excess (hirsutism, ance, libido)
Central obesity (moon face, buffalo hump)
2 etiologies of Cushing's syndrome
ACTH dependent (mostly)
Etiologies of ACTH dependent Cushing's syndrome
Cushing's disease (pituitary hypersecretion of ACTH)
Ectopic secretion of ACTH by non-pituitary tumor
Etiologies of ACTH independent Cushing's Syndrome
Iatrogenic or factitious Cushing's syndromes (administer excessive synthetic glucocorticoid)
Adrenocortical adenomas and carcinomas
How to distinguish b/w ACTH dependent and independent Cushings?
Dependent: cortisol is high and ACTH is high, more females
Independent: cortisol high and ACTH low
How to diagnose Cushing's syndrome
Exclude exogenous glucocorticoids
Gold standard: 24 hr urinary free cortisol excretion
Late night salivary cortisol
Low dose dexamethasone suppression tests
What is the low-dose dexamethasone suppression test?
1 mg oral dose of dexamethasone administered at 11 pm and then serum cortisol levels are measured at 8 am the next day
Abnormal dexamethasone suppression test
Elevated cortisol above 5 mcg/dL
What are you suspicious for with an abnormal dexamethasone suppression test?
Non-suppressible cortisol production from ACTH independent etiology
Other tests to diagnose Cushing's syndrome
MRI (for pituitary tumor)
CXR (r/o lung masses as source of tumor)
Pelvic u/s (rule out ovarian mass)
CT abdomen (evaluate for adrenal tumor)
Management of Cushing's syndrome due to exogenous corticosteroids
Taper to lowest therapeutic dose to control sxs
Management of Cushing's syndrome due to a pituitary adenoma
Management of Cushing's syndrome due to adrenal tumor
Management of Cushing's syndrome due to adrenal hyperplasia, inoperable tumor or other malignancy
Medical therapy is warranted
1st line med for Cushing's syndrome
Ketoconazole (add metyrapone if ineffective)
What can mitotane be used for?
Functions of aldosterone
Increase ECF vol
Increase tubular reabsorption of sodium
Promote excretion of potassium
Most common etiologies of Conn's syndrome (primary hyperaldosteronism)
Bilateral idiopathic adrenal hyperplasia
Unilateral aldosterone-producing adenoma
Features of Conns
HTN and hypokalemia
(muscle weakness, paresthesias, HA, polyuria, polydipsia)
Who do you want to consider testing for Conns?
HTN and hypokalemia
Resistant HTN (3 drugs and poor BP control)
Adrenal incidentaloma and HTN
Onset of HTN at young age
Severe HTN (>150 SBP or >100 DBP)
When considering secondary HTN
What is a CT used for in Conns?
Evaluate for possible adrenal adenoma