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Endocrine 3: Adrenal Gland
Function and Disorders of the Adrenal Gland
Terms in this set (30)
What hormones are secreted by the adrenal medulla?
epinephrine and norepinephrine
What hormones are secreted by the adrenal cortex?
aldosterone, cortisol, androgens
(salt, sugar, sex)
What do mineralocorticoids (aldosterone) do?
increase renal Na+ absorption, K+/H+ excretion
What are effects of high levels of aldosterone?
hypertension, hypokalemia, met alkalosis
What is the main androgen produced by the adrenal cortex?
What are the effects of excess cortisol?
easy fatiguability, prox. muscle weakness, easy bruising, emotional lability, amenorrhea, hirsutism, acne
What are physical signs of Cushing syndrome?
facial plethora, abdominal striae, cervicodorsal fat pad, truncal obesity, thin skin
What are comorbidities of Cushing syndrome?
insulin resistance, osteoporosis, hypertension, hypokalemia, met. alkalosis
Which genes control steroid synthesis in the adrenal cortex?
What hormones are affected by a defect in 21-hydroxylase?
increased progesterone, 17OH progesterone since not converted to aldosterone and cortisol
increase in DHEAS
Which gene defect most commonly associated with CAH?
most are due to CYP21A2 mutation (autosomal recessive)
What is Cushing disease?
ACTH-secreting pituitary adenoma
What is Cushing syndrome?
excess glucocorticoids caused by iatrogenic, ectopic ACTH secretion (small cell lung CA), bilateral adrenal hyperplasia, adrenal adenomas and carcinomas
What is the ACTH level in Cushing disease?
What are initial tests in Cushing syndrome?
24-hour urinary free cortisol
late-night salivary cortisol
low-dose (1mg) dex suppression test
if one is abnormal, confirm with second test
What situations result in pseudo-Cushing syndrome?
depression, obesity, alcohol abuse, uncontrolled DM
What tests differentiate between ACTH-independent and ACTH-dependent Cushing syndrome?
high ACTH level is ACTH-dependent (pituitary or ectopic production)
undetectable ACTH is ACTH-independent (adrenal tumor)
How does adrenal insufficiency present?
weakness, weight loss, N/V, hypoglycemia, moodiness, hypercalcemia
What type of adrenal insufficiency presents with abnormal K+ levels?
hyperkalemia in primary AI due to hypoaldosteronism and low DHEAS
What is the effect of aldosterone on serum Na+ and K+?
increase Na+ resorption, K+ and H+ secretion
Primary Hyperaldosteronism: low renin, hypertension, hypokalemia, met alkalosis
Secondary hyperaldosteronism: high renin and others
What syndrome is associated with untreated hypertension and low K+?
What is the best screening test for primary hyperaldosteronism?
plasma aldosterone concentration (PAC) and plasma renin activity (PRA)
What situations other than aldosterone excess can cause hypertension and hypokalemia?
licorice ingestion and Cushing's syndrome
What test confirms primary hyperaldosteronism? (PAC high, PRA low)
saline suppression test
What is the most common cause of hypoaldosteronism?
decreased renin in diabetic pts with mild renal failure (hyporeninemic hypoaldosteronism)
What is the workup for hypoaldosteronism?
First, r/o AI (perform ACTH stim test)
Measure renin and aldo during upright posture and salt restriction (renin low in hypoaldo but high in AI)
What is the initial workup of a pheo?
24-hour urinary fractionated metanephrines (wean off tricyclics and cyclobenzaprine before)
Plasma free metanephrines; sensitivity is high (neg excludes disease); specificity lower (false-pos common)
What is next step if biochem markers support pheo?
CT or MRI
What is presurgery treatment for pheo resection?
Alpha blockade (phenoxybenzamine) 2 weeks, then beta blockade
What is 1st step in evaluating adrenal incidentalnoma?
low dose overnight dexa suppresion test (eval for Cushings)
Plasma free metanephrines (pheo)
Blood pressure and K+ (hyperaldo if hypokalemia/HTN present)
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