Endocrine Flashcards
where is the drainage of the L adrenal vein?
left renal vein
where is the drainage of the R adrenal vein?
inferior vena cava
what is CRH?
corticotropin-releasing hormone
- released from anterior hypothalamus
- causes release of ACTH from anterior pituitary
what is ACTH?
adrenocorticotropic hormone
- released normally by anterior pituitary
- causes adrenal gland to release cortisol
what feeds back to inhibit ACTH secretion?
cortisol
what is Cushing’s syndrome?
excessive cortisol production
what is the most common cause of Cushing’s syndrome?
iatrogenic
what is the second most common cause of Cushing’s syndrome?
Cushing’s disease
what is Cushing’s disease?
Cushing’s syndrome caused by excess production of ACTH by anterior pituitary
what is an ectopic ACTH source?
tumor not found in the pituitary that secretes ACTH, which in turn causes adrenal gland to release cortisol without the normal negative feedback loop
what are the sign/symptoms of Cushing’s syndrome?
truncal obesity, hirsutism, ‘moon’ facies, acne, ‘buffalo hump’, purple striae, HTN, diabetes, weakness, depression, easy bruising, myopathy
how can cortisol levels be indirectly measured over a short duration?
urine cortisol or breakdown product of cortisol (17-OHCS)
what is a direct test of serum cortisol?
serum cortisol level
- highest in the morning
- lowest at night
what initial tests should be performed in Cushing’s syndrome?
electrolytes
serum cortisol
urine-free cortisol, urine 17-OHCS
low-dose dexamethasone-suppression test
what is the low-dose dexamethasone suppression test?
dexamethasone is a synthetic cortisol that results in negative feedback on ACTH secretion and subsequent cortisol secretion in healthy patients
what happens in the low-dose dexamethasone suppression test in patients with Cushing’s syndrome?
dexamethasone does not suppress their cortisol secretion
after the dexamethasone test in Cushing’s workup, what is next?
check ACTH levels
in ACTH-dependent Cushing’s syndrome, how do you differentiate between pituitary vs. ectopic ACTH source?
high-dose dexamethasone test
- pituitary source: cortisol is suppressed
- ectopic ACTH source: no cortisol suppression
Treatment of adrenal adenoma:
adrenalectomy
treatment of adrenal carcinoma
surgical excision
treatment of ectopic ACTH-producing tumor
surgical excision, if feasible
treatment of Cushing’s disease
transphenoidal adenomectomy
what is a complication of bilateral adrenalectomy?
Nelson’s syndrome
What is Nelson’s syndrome?
functional pituitary adenoma producing excessive ACTH and mass effect producing visual disturbances, hyperpigmentation, amenorrhea, with elevated ACTH levels
what is pheochromocytoma?
tumor of the adrenal medulla and sympathetic ganglion (from chromaffin cell lines)
- produces catecholamines (NE > epi)
what are the associated risk factors of pheochromocytoma?
MEN-II, fam hx, von Recklinghausen disease, von Hippel-Lindau disease
what are the signs/symptoms of pheochromocytoma?
classic triad:
- hypertension
- headache
- episodic diaphoresis
also, HTN, pallor-> flushing, anxiety, weight loss, tachycardia, hyperglycemia
how can the pheochromocytoma symptoms triad be remembered?
PHEochromocytoma
- Palpitations
- Headache
- Episodic diaphoresis
what diagnostic tests should be performed for suspected pheochromocytoma?
urine screen: VMA, metanephrine, and normetanephrine
urine/serum epinephrine/norepinephrine levels
what are other common lab findings in pheochromocytoma?
hyperglycemia - epinephrine -> increase glucose - norepinephrine -> decrease insulin polycythemia - resulting from intravascular volume depletion
what is the classic pheochromocytoma ‘rule of 10’s’?
10% malignant 10% bilateral 10% in children 10% multiple tumors 10% extra-adrenal
what is the preoperative/medical treatment of pheochromocytoma?
increase intravascular volume
- α-blockade: phenoxygenzamine or prazosin
- to allow reduction in catecholamine-induced vasoconstriction and resulting volume depletion
in the patient with pheochromocytoma, what must be ruled out?
MEN-II
- almost all cases are bilateral
what is the organ of Zuckerkandl?
body of embryonic chromaffin cells around the abdominal aorta (heart he IMA)
- normally atrophies during childhood, but is the most common site of extra-adrenal pheochromocytoma
what is Conn’s syndrome?
primary hyperaldosteronism
- due to high aldosterone production
what are the common sources of Conn’s syndrome?
adrenal adenoma or adrenal hyperplasia
what is the normal physiology for aldosterone secretion
low BP in renal afferent arteriole & hyponatremia/hyperkalemia -> renin secretion from juxtaglomerular cells -> angiotensinogen -> angiotensin I -> ACE from the lung -> angiotensin II -> adrenal glomerulosa cells secrete aldosterone
what is the normal physiologic effect of aldosterone?
sodium retention for exchange of potassium in kidney
- fluid retention
- increased BP
what are the sign/symptoms of Conn’s syndrome?
hypertension, headache, polyuria, weakness
what are the two classic clues of Conn’s syndrome?
hypertension
hypokalemia
what is Addison’s disease?
acute adrenal insufficiency
what are the renin levels in patients with primary hyperaldosteronism?
normal or low
what are the electrolyte findings in Addison’s disease?
hyperkalemia
hyponatremia
what is an insulinoma?
insulin-producing tumor arising from ß-cells
what are the associated risks of an insulinoma?
MEN-I syndrome
- pituitary
- pancreas
- parathyroid tumors
what are the signs/symptoms of an insulinoma?
sympathetic nervous system symptoms resulting from hypoglycemia
- palpitations, diaphoresis, tremulousness, irritability, weakness
what are the neurological symptoms of an insulinoma?
personality changes, confusion, obtundation, seizures, coma
what is Whipple’s triad?
- hypoglycemic symptoms produced by fasting
- blood glucose <50 during symptomatic attack
- relief of symptoms by administration of glucose
what lab tests should be performed in suspected insulinoma?
fasting hypoglycemia with inappropriately high levels of insulin
- 72hr fast, then check glucose & insulin q 6hrs
what is the medical treatment of an insulinoma?
diazoxide
what is a glucagonoma?
glucagon-producing tumor
where is a glucagonoma located?
pancreas (usually in the tail)
what are the symptoms of a glucagonoma?
necrotizing migratory erythema (usually below the waist), glossitis, stomatitis, diabetes
what are the skin findings in a glucagonoma?
necrotizing migratory erythema
- red, often psoriatic-appearing rash
- serpiginous borders
- over the trunk and limbs
what stimulation test is used for a glucagonoma?
tolbutamide stimulation test
- IV tolbutamide -> elevated glucagon levels
what test is used for localization of a glucagonoma?
CT scan
what is the medical treatment of necrotizing migratory erythema?
somatostatin
IV amino acids
what is the treatment of a glucagonoma?
surgical resection
what is a somatostatinoma?
pancreatic tumor that secretes somatostatin
what is the diagnostic triad of a somatostatinoma?
DDD
- diabetes
- diarrhea (steatorrhea)
- dilation of the gallbladder with gallstones
what is used to make the diagnosis of a somatostatinoma?
CT scan and somatostatin level
what is the treatment of a somatostatinoma?
resection
what is Zollinger-Ellison syndrome?
gastrinoma
- non-ß islet cell tumor of the pancreas
- produces gastrin -> gastric hyper secretion of HCl -> GI ulcers
what is the associated syndrome of Zollinger-Ellison syndrome?
MEN-I
- pituitary
- pancreas
- parathyroid
with gastrinoma, what lab tests should be ordered to scream for MEN-I?
calcium level
PTH level
what are the signs/symptoms of Zollinger-Ellison syndrome?
peptic ulcers, diarrhea, weight loss, abdominal pain
what causes the diarrhea in Zollinger-Ellison syndrome?
massive acid hyper secretion and destruction of digestive enzymes
what are the signs of Zollinger-Ellison syndrome?
peptic ulcer disease
- epigastric pain, hematemesis, melena, hematochezia
GERD, diarrhea, recurrent ulcers, ulcers in unusual locations
what is the secretin-stimulation test?
IV secretin is administered and gastrin level is determined
- patients with Z-E syndrome will have a paradoxic increase in gastrin
what are the classic secretin stimulation results?
NL - decreased gastrin
Z-E syndrome - increased gastrin
define Passaro’s triangle
aka ‘gastrinoma triangle’
- cystic duct/CBD junction
- junction of the second and third portions of the duodenum
- neck of the pancreas
what is the medical treatment for Zollinger-Ellison syndrome?
H2 blockers, omeprazole, somatostatin
what is multiple endocrine neoplasia also known as?
MEN syndrome
what is MEN?
inherited condition of propensity to develop multiple endocrine tumors
how is MEN inherited?
AD with significant degree of variation in penetrance
which patients should be screened for MEN?
all family members of patients diagnosed with MEN
what is the gene defect in MEN-I?
chromosome 11
what are the most common tumors of MEN-I?
parathyroid hyperplasia pancreatic islet cell tumors - gastrinoma: ZE syndrome - insulinoma pituitary tumors
what are the highest-yield screening lab tests for MEN-I?
calcium
PTH
gastrin
prolactin
what is the genetic defect in MEN-IIa?
RET
what are the most common tumors of MEN-IIa?
MPH
- medullary thyroid carcinoma (calcitonin secreted)
- pheochromocytoma (catecholamine excess)
- hyperparathyroidism (hypercalcemia)
what are the best screening lab tests for MEN-II?
calcitonin level calcium levels PTH catecholamines and metabolites RET gene testing
what are the most common abnormalities in MEN-IIb?
MMMP
- mucosal neuromas
- medullary thyroid carcinoma
- marfanoid habitus
- pheochromocytoma
what is the anatomic distribution of medullary thyroid carcinoma in MEN-II?
almost always bilateral
what are the physical findings/signs of MEN-IIb?
mucosal neuromas
marfinoid habitus
pes cavus/planum
constipation
what is the major difference between MEN-IIa and MEN-IIb?
MEN-IIa = parathyroid hyperplasia MEN-IIb = NO parathyroid hyperplasia
what type of parathyroid disease is associated with MEN-I and MEN-IIa?
hyperplasia
