Adrenal gland Flashcards
What are the three major classes of steroids produced by the adrenal cortex
glucocorticoids mineralocorticoids and adrenal androgens
What do glucocorticoids regulate
metabolism and immune responses
What do mineralocorticoids regulate
blood pressure vascular volume and electrolytes
What do adrenal androgens influence in females
secondary sexual characteristics
Which zone of the adrenal cortex produces mineralocorticoids
the glomerulosa
Which hormone is the primary mineralocorticoid
aldosterone
Which zone of the adrenal cortex produces glucocorticoids
the fasciculata
Which hormone is the primary glucocorticoid
cortisol
Which zone of the adrenal cortex produces adrenal androgens
the reticularis
What is the primary adrenal androgen
dehydroepiandrosterone (DHEA)
What is the substrate for adrenal steroid biosynthesis
cholesterol
How is cholesterol taken up by the adrenal cortex
through the LDL receptor
What increases LDL receptor numbers in the adrenal cortex
long-term ACTH stimulation
What does excess cortisol cause
Cushing’s syndrome
What does excess aldosterone cause
aldosteronism
What does excess adrenal androgens cause
adrenal virilism
What are the two main causes of Cushing’s syndrome
exogenous glucocorticoids or endogenous adrenal activation
What percentage of Cushing’s syndrome cases are ACTH dependent
80%
What are the two main causes of ACTH-independent Cushing’s syndrome
adrenal adenoma and adrenal carcinoma
What are the two main causes of ACTH-dependent Cushing’s syndrome
corticotrope adenoma and ectopic ACTH secretion
What is the typical body habitus in Cushing’s syndrome
centripetal obesity
What blood pressure reading is commonly seen in Cushing’s syndrome
greater than 150/90
What skin finding is characteristic of Cushing’s syndrome
broad violaceous striae
What psychiatric symptoms can occur in Cushing’s syndrome
personality changes
What urinary test is a good screening tool for Cushing’s syndrome
24-hour urine free cortisol excretion
What can cause pseudo-Cushing states
psychiatric disorders chronic pain severe exercise alcoholism diabetes and obesity
What test detects loss of diurnal cortisol variation
midnight salivary cortisol level
What is the most effective treatment for Cushing’s syndrome
surgical resection of the ACTH or cortisol-producing lesion
What is an alternative treatment if surgery fails in ACTH-dependent Cushing’s syndrome
bilateral adrenalectomy
What is the best surgical treatment for Cushing’s disease
transsphenoidal resection of a microadenoma
What is a non-surgical treatment option for Cushing’s disease
pituitary radiation therapy with adjunctive medical therapy
What test is done after an abnormal urine free cortisol result
plasma ACTH and high-dose suppression test
What does undetectable ACTH and no suppression indicate
adrenal tumor
What does high ACTH and no suppression indicate
ectopic ACTH secretion
What does high ACTH and partial suppression indicate
pituitary adenoma
What are common symptoms of mineralocorticoid excess
fatigue muscle weakness and cramps
What condition is often suspected in mineralocorticoid excess
hypertension
What electrolyte abnormality is associated with mineralocorticoid excess
hypokalemia
What are the two main causes of mineralocorticoid excess
primary adrenal disease and nonadrenal causes
What happens to renin levels in primary adrenal mineralocorticoid excess
they are low
What happens to renin levels in nonadrenal causes of mineralocorticoid excess
they are high
What are three nonadrenal causes of mineralocorticoid excess
congestive heart failure cirrhosis and decreased renal blood flow
What is the most common cause of primary hyperaldosteronism
aldosterone-producing adenoma
What is a rare adrenal tumor that can cause primary hyperaldosteronism
aldosterone-producing adrenal carcinoma
What are three causes of secondary hyperaldosteronism
renovascular hypertension diuretics and renin-secreting tumors
What common food can cause apparent mineralocorticoid excess
licorice
What enzyme does licorice inhibit
renal 11β-hydroxysteroid dehydrogenase type 2
What ion is reabsorbed in excess in primary hyperaldosteronism
sodium
What ion is excessively lost in primary hyperaldosteronism
potassium
What is a common blood pressure finding in mineralocorticoid excess
severe diastolic hypertension
What is the main test used to screen for primary aldosteronism
morning plasma aldosterone to renin ratio
What aldosterone to renin ratio suggests primary hyperaldosteronism
greater than 20 to 1
What are the four confirmatory tests for primary hyperaldosteronism
oral sodium loading saline infusion fludrocortisone suppression and captopril challenge
What imaging is done after a positive confirmatory test for primary hyperaldosteronism
adrenal CT
What is the surgical treatment for unilateral primary hyperaldosteronism
laparoscopic adrenalectomy
What is the medical treatment for bilateral adrenal hyperplasia
mineralocorticoid receptor antagonist
What medication is used to treat primary hyperaldosteronism if surgery is not possible
spironolactone or amiloride
What are the two main categories of adrenal insufficiency
primary adrenal failure and secondary ACTH deficiency
What is lost in primary adrenal insufficiency
both glucocorticoid and mineralocorticoid activity
What hormone is deficient in secondary adrenal insufficiency
cortisol
What is the main symptom of Addison’s disease
asthenia
(abnormal physical weakness or lack of energy)
What causes hyperpigmentation in Addison’s disease
excess ACTH
Where is hyperpigmentation most commonly seen
elbows hand creases areolae and mucous membranes
What is a common cardiovascular finding in Addison’s disease
arterial hypotension
What are common gastrointestinal symptoms in Addison’s disease
nausea vomiting diarrhea and abdominal pain
What is the presentation of acute adrenal insufficiency
hypotension confusion circulatory collapse and fever
What can trigger an adrenal crisis
hemorrhage metastasis or acute infection
What is a key laboratory finding in adrenal insufficiency
subnormal cortisol response to ACTH stimulation
What electrolyte abnormalities are seen in adrenal insufficiency
hyponatremia and hyperkalemia
Why does hyponatremia occur in adrenal insufficiency
sodium loss due to aldosterone deficiency
Why does hyperkalemia occur in adrenal insufficiency
aldosterone deficiency and acidosis
What is the screening test for adrenal insufficiency
plasma cortisol 30-60 min after cosyntropin
What indicates possible adrenal insufficiency on screening
subnormal cortisol response
What distinguishes primary from secondary adrenal insufficiency
ACTH and aldosterone response to cosyntropin
What ACTH level is seen in primary adrenal insufficiency
high
What ACTH level is seen in secondary adrenal insufficiency
low or normal
What is the emergency treatment for adrenal crisis
IV hydrocortisone and saline with dextrose
Why is dexamethasone used before confirming adrenal insufficiency
it does not interfere with cortisol measurement
What is the maintenance therapy for adrenal insufficiency
prednisone and fludrocortisone
How is prednisone dosed for maintenance
5 mg PO every morning
What is given in primary adrenal insufficiency for mineralocorticoid replacement
fludrocortisone
How should steroid doses be adjusted during illness or surgery
increased with IV hydrocortisone tapering after recovery
What are catecholamine-secreting tumors called when they arise in the adrenal medulla
pheochromocytomas
What are extra-adrenal catecholamine-secreting tumors called
paragangliomas
What is a common psychological symptom of pheochromocytoma
anxiety and fear of impending death
What are common cardiovascular symptoms of pheochromocytoma
palpitations hypertension and chest pain
What are common gastrointestinal symptoms of pheochromocytoma
nausea vomiting and epigastric pain
What are common neurological symptoms of pheochromocytoma
headache tremor and diaphoresis
How can pheochromocytoma-related hypertension present
sustained paroxysmal or normal
What are common signs of a pheochromocytoma spell
forceful heartbeat pallor tremor headache and diaphoresis
What can trigger a pheochromocytoma spell
postural change anxiety medications exercise or increased intra-abdominal pressure
How long do pheochromocytoma spells typically last
15 to 20 minutes
What is the most reliable biochemical test for pheochromocytoma
24-hour urine metanephrines and catecholamines
What laboratory finding confirms pheochromocytoma
increased plasma or urine fractionated catecholamines and metanephrines
What medications can falsely elevate catecholamine levels
tricyclic antidepressants levodopa amphetamines decongestants ethanol and clonidine withdrawal
When should imaging be performed for pheochromocytoma
only after biochemical confirmation
What is the first-line imaging test for pheochromocytoma
MRI or CT of the adrenal glands and abdomen
What is the primary treatment for pheochromocytoma
complete surgical resection
Why is preoperative medical therapy required in pheochromocytoma
to control blood pressure and prevent intraoperative crises
What is the recommended sequence for adrenergic blockade in pheochromocytoma
α-adrenergic blockade first then β-adrenergic blockade
How long before surgery should α-adrenergic blockade be started
7 to 10 days
Why must α-blockade be initiated before β-blockade
to prevent unopposed α-adrenergic stimulation and worsening hypertension
What is the preferred drug for preoperative blood pressure control
phenoxybenzamine
What are the three zones of the adrenal cortex and their secretions
zona glomerulosa aldosterone zona fasciculata cortisol zona reticularis androgens
What hormone controls cortisol and androgen secretion
ACTH
When is cortisol highest and lowest
highest at 8 AM lowest at 8 PM
What controls aldosterone secretion
serum sodium and renin-angiotensin system
What is the main cause of Cushing syndrome
ACTH-producing pituitary adenoma
What are common symptoms of Cushing syndrome
truncal obesity moon face hypertension muscle weakness and osteoporosis
What is the most sensitive test for early Cushing syndrome
24-hour urine free cortisol
How is Cushing syndrome differentiated from stress-induced cortisol elevation
dexamethasone suppression test
What does the short dexamethasone test show in Cushing syndrome
no suppression and cortisol >10 ug/dL
What ACTH level is seen in adrenal tumors
low
What ACTH level is seen in ectopic ACTH production
very high often >300 pg/mL
What does the high-dose dexamethasone test show in Cushing disease
cortisol suppression
What metabolic abnormalities are found in Cushing syndrome
hyperglycemia hypokalemia metabolic alkalosis
What is the main cause of Addison disease
autoimmune adrenal destruction
What are key symptoms of Addison disease
weakness vomiting diarrhea hyperpigmentation hypotension and fasting hypoglycemia
Why does Addison disease cause hyperpigmentation
increased ACTH precursor stimulates MSH
What laboratory test is diagnostic for Addison disease
low morning plasma cortisol
What test confirms adrenal insufficiency
synacthen (cosyntropin) stimulation test
How is secondary hypoadrenalism differentiated from Addison disease
low ACTH without hyperpigmentation
What test differentiates pituitary and hypothalamic causes of adrenal insufficiency
CRH stimulation test
What electrolyte abnormalities are seen in Addison disease
hyponatremia hyperkalemia metabolic acidosis
What is Conn’s syndrome
primary hyperaldosteronism due to excess aldosterone
What is the most common cause of Conn’s syndrome
bilateral adrenal hyperplasia
What is the main cause of secondary hyperaldosteronism
excessive renin-angiotensin activation
What is the most common symptom of hyperaldosteronism
resistant hypertension
What is the key laboratory finding in primary hyperaldosteronism
hypokalemia
What happens to plasma renin in primary hyperaldosteronism
decreased
What happens to plasma renin in secondary hyperaldosteronism
increased
What test confirms primary hyperaldosteronism
PAC/PRA ratio >25-30
What is the purpose of the saline suppression test
to confirm primary hyperaldosteronism
What is the effect of captopril in normal subjects
decreases aldosterone to <15 ng/dL
Congenital Adrenal Hyperplasia (CAH)
is caused by mutations in genes encoding enzymes involved in glucocorticoid synthesis
CAH presents a mixed picture of cortisol deficiency and adrenal androgen overproduction
cortisol deficiency stimulates CRH and ACTH leading to hyperplasia and excess androgen production
CAH is inherited as an autosomal recessive trait
95% of cases are due to 21α-hydroxylase deficiency while most others are due to 11β-hydroxylase deficiency
Salt-wasting form of 21α-hydroxylase deficiency
appears in infancy with hypotension and high mortality due to inadequate cortisol and aldosterone synthesis
Laboratory features of salt-wasting 21α-hydroxylase deficiency
include hyponatremia
Simple virilizing form of 21α-hydroxylase deficiency
presents in neonatal or early childhood with androgen excess and no salt loss due to nearly normal mineralocorticoid production
Non-classical 21α-hydroxylase deficiency
presents in adolescence or early adulthood with androgen excess while cortisol and aldosterone production are preserved
Marked elevation of 17-hydroxyprogesterone (17-OHP)
is the key diagnostic feature of classical 21α-hydroxylase deficiency
ACTH stimulation test
is useful in non-classical CAH where ACTH injection results in a significant increase in 17-OHP
Laboratory findings in classical CAH
include increased androgens (DHEA and DHEAS)
11β-hydroxylase deficiency
leads to cortisol deficiency
Accumulation of deoxycorticosterone (DOC) in 11β-hydroxylase deficiency
results in sodium retention
Elevated 11-deoxycortisol
is the best biochemical marker for diagnosing 11β-hydroxylase deficiency
Pheochromocytomas
are catecholamine-secreting tumors arising from chromaffin cells in the adrenal medulla
Common symptoms of pheochromocytoma
include severe headaches
Catecholamines
include epinephrine and norepinephrine
Best initial biochemical test for pheochromocytoma
is plasma or urinary metanephrines due to their high sensitivity
Plasma metanephrines testing
should be done in the supine position after 20-30 minutes of rest to avoid false positives
Catecholamines are less sensitive for pheochromocytoma diagnosis
because they are secreted intermittently and have a short plasma half-life
Urinary vanillylmandelic acid (VMA)
has poor sensitivity and is not commonly used for pheochromocytoma diagnosis
Clonidine suppression test
is used when metanephrine levels are mildly elevated to differentiate true pheochromocytoma from stress-related increases
Failure of normetanephrine suppression after clonidine
indicates pheochromocytoma since tumor catecholamine secretion is independent of sympathetic control
Other laboratory findings in pheochromocytoma
include hyperglycemia and diabetes mellitus
