Adrenal Disorders 2 Flashcards
adrenal incidentalomas - overview
*an adrenal tumor that is discovered on imaging that is being done for a problem unrelated to the adrenal glands
*very common with age, esp > 50
*2 questions you have to answer:
1. is is potentially malignant? [look at imaging]
2. is it functioning / secreting a hormone? [use hormone testing]
adrenal incidentalomas - ddx
*is it malignant?
-adrenal carcinoma
-pheochromocytoma
-metastases
-lymphoma
*is it secreting hormones?
-cortisol
-aldosterone
-catecholamines/metanephrines
-DHEA
pheochromocytoma - overview
*arises from the adrenal medulla
*derived from chromaffin cells (neural crest origin)
*most secrete catecholamines and their metabolites (metanephrines)
*as a result, patients have symptoms of abrupt epinephrine / norepinephrine release (fight or flight), often in an episodic fashion
pheochromocytoma - symptoms
*classically, symptoms are EPISODIC / occur in spells
*classic triad: EPISODIC headache, sweating, palpitations
*hypertension (can be sustained, paroxysmal, or both)
*headache (often episodic)
*diaphoresis (sweating)
*anxiety / tremulousness
*palpitations
*pallor (not flushing)
pheochromocytoma - inheritability
*pheochromocytoma and paragangliomas (extra-adrenal pheochromocytoma) have the highest degree of heritability among ALL tumors
*20% of patients with a pheo, and up to 50% of pts with a paraganglioma, have an underlying germline mutation:
-SDHx mutations
-RET mutation (MEN 2a & 2b)
-VHL (CNS hemangioblastomas, renal cancer, pancreatic neuroendocrine tumors)
-NF1 (cutaneous neurofibromas, cafe-au-lait spots)
pheochromocytoma - diagnosis
*evaluate levels of fractionated metanephrines (normetanephrine and metanephrine) in the blood or urine
pheochromocytoma - treatment
*surgery to remove tumor:
*preoperative alpha blockade and high sodium diet:
-must protect against release of epinephrine during manipulation of the tumor intraoperatively
-use alpha-blockers (phenoxybenzamine, doxazosin) to target a low normal blood pressure
-can add a beta blocker second to treat any tachycardia that occurs from the alpha blocker
-high sodium diet leading up to surgery to expand intravascular volume
why do you need to give an alpha blocker prior to giving a beta blocker in pts with pheochromocytoma?
*MUST GIVE ALPHA BLOCKER BEFORE BETA BLOCKER:
-beta 2 receptors cause vasodilation, while alpha 1 causes vasoconstriction (these balance each other)
-if you give a beta blocker, then the pt will have unopposed alpha activity → worsening hypertension
*classically on exam questions, you give phenoxybenzamine because it is an IRREVERSIBLE alpha blocker
hyperaldosteronism - etiologies
*can be primary (problem is in the adrenal gland itself) or secondary (problem outside the adrenal gland)
1. primary hyperaldosteronism:
-aldosterone secreting adenoma
-bilateral adrenal hyperplasia
-rare genetic forms
2. secondary hyperaldosteronism:
-renovascular disease
-reninoma (juxtaglomerular cell tumor)
-edematous disorders
primary hyperaldosteronism - overview
*most common cause of secondary hypertension
*caused by:
1. aldosterone-secreting adenoma (Conn’s syndrome)
2. bilateral or unilateral adrenal hyperplasia
3. familial hyperaldosteronism
*pts present with hypertension, +/- hypokalemia and metabolic alkalosis
*note: sodium is usually normal
screening criteria for primary hyperaldosteronism
*suggested to screen for primary hyperaldosteronism in the following circumstances:
-resistant hypertension
-hypokalemia
-history of early onset hypertension
-incidental discovery of adrenal mass
-history of stroke at young age (<40)
primary hyperaldosteronism - diagnosis
- measure an aldosterone and renin level: low renin, high aldosterone
- use the aldosterone-to-renin ratio (ARR): ARR > 20 is concerning for primary hyperaldosteronism
- additional confirmatory testing: salt loading test (IV or oral) should decrease aldosterone
primary hyperaldosteronism - treatment
- surgical removal (must establish aldosterone is coming from a single adrenal gland via adrenal vein sampling)
- medications: mineralocorticoid receptor antagonists: spironolactone or eplerenone
-titrate to potassium > 4.5 and renin > 1.0
syndrome of apparent mineralocorticoid excess (SAME) - overview
*11-beta HSD prevents cortisol from binding to the mineralocorticoid receptor (aldosterone’s receptor)
*any condition where 11-beta hydroxysteroid dehydrogenase (11-beta HSD) is missing, inhibited, or overwhelmed:
1. autosomal recessive disorder with mutation in 11-beta HSD
2. black licorice ingestion (glycyrrhizic acid)
3. ectopic ACTH syndrome (high levels of cortisol)
*labs: low renin, low aldosterone
Liddle’s Syndrome - overview
*rare autosomal dominant mutation resulting in constitutively active ENaC channels in the principle cell of the collecting duct of the kidney
*labs: low renin, low aldosterone
