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Endocrine > Lec 14 Adrenal III > Flashcards

Lec 14 Adrenal III Flashcards

1
Q

How common is primary aldosteronism?

A

5-10% of all cases of “essential” hypertension

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2
Q

What are syndromes of apparent mineralocorticoid excess?

A

neither DOC or aldosterone is elevated
- cortisol made in excess or not properly inactivated to cortisone [in 11B-HSD deficiency] and is acting on the mineralocorticoid receptor

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3
Q

What are the actions of aldosterone?

A
  • exchange Na and H for K at distal collecting tubule [DCT]

- increase Na and volume, BP, decrease K [hypokalemia]

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4
Q

What are some things that regulate aldosterone levels?

A
  • RAAS [primary]
  • hyperkalemia
  • ACTH
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5
Q

What is the escape phenomenon?

A

atrial natriuretic factor [ANF} made in heart gets stimulated by high BP and modulates clinical effects of excess mineralocorticoid [aldosterone]

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6
Q

What should you with if high BP and unprovoked hypokalemia or severe diuretic-induced hypokalemia?

A

primary aldosteronism = 50% of cases

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7
Q

What are the two major causes of primary hyperaldosteronism?

A
  • aldosterone producing adenoma [1/3]

- idiopathic hyperaldosteronism [bilateral] [2/3]

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8
Q

What number value tells you primary aldosteronism?

A

high aldosterone in setting of suppressed renin

aldosterone: renin ratio > 20

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9
Q

WHat are characteristics of aldosteronomas?

A

very small; may not be seen on imaging

up to 50% have bilateral disease so have to identify source of excess aldosterone

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10
Q

What is medical therapy for aldosteronoma?

A

aldosterone antagonists [spironolactone or epleronone]

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11
Q

What is familial aldosteronism?

A

recombination of genes encoding CYP11B1 and CYP11B2 –> chimeric gene that encodes hybrid proteins/steroids

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12
Q

What is treatment for familial aldosteronism?

A

suppress ACTH with glucocorticoids [b/c the chimeric gene is under ACTH control]

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13
Q

How do you localize site of aldosteronoma?

A

bilateral adrenal venous sampling; compare ratio

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14
Q

What mutation found in aldosterone producing adenomas?

A

CNJJ5 mutation in gene encoding the K channel

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15
Q

What is adrenal medulla derived from?

A

neuroectoderm –> phechromoblasts

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16
Q

What is the adrenal cortex derived from?

A

true glandular tissue

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17
Q

What is role of adrenal medulla in sympathetic nervous system?

A

serve as amplifiers of SNS

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18
Q

WHat 3 major hormones secreted by adrenal medulla?

A
  • epinephrine
  • norepinephrine
  • dopamine
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19
Q

What is the rate limiting step in steroid hormone production in medulla?

A

conversion of tyrosine to dihydroxyphenlalanine [DOPA] cautalzyed by tyrosine hydroxylase

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20
Q

From what AA are catecholamines synthesized?

A

tyrosine

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21
Q

What converts NE to Epi? What induces it?

A

PNMT [phenylethanolamine N-methyltransferase] converts NE to Epi
induced by cortasol

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22
Q

Does adrenal medulla secrete more epinephrine or NE?

A

secretes 4x more Epi

[NE total circulating levels higher b/c of NE release from postganglionic sympathetic neurons]

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23
Q

What stimulates catecholamine release from adrenal medulla?

A
  • postural changes [supine to standing]
  • low intravascular volume
  • hypoglycemia
  • severe illness
  • emotional stress [fear or rage]
  • tumors [pheochromocytomas and paragangliomas]
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24
Q

What are the major signals for catecholamine release?

A
  • decrease BP, blood volume, or glucose
25
Q

What is epi/NE affinity for a1/a2 receptors?

A

epi > NE for a1/a2

26
Q

What is epi/NE affinity for B1 receptors?

A

epi = NE

27
Q

What is epi/NE affinity for b2 receptors?

A

epi > > > NE

overall effect = increased contractility and vasodilation

28
Q

Do adrenal medulary tumors that hypersecrete primarily Epi cause hypertension or hypotension?

A

hypotension b/c have super high affinity for B2 which causes vasodilation

29
Q

What things do catecholamines increase?

A
  • blood glucose
  • lipolysis
  • skeletal muscle blood flow/contractility
  • HR
  • CO
  • BP
30
Q

What things do catecholamines decrease?

A
  • visceral blood flow
  • GI motility
  • urine output
31
Q

What is a pheochromocytoma?

A

adrenal medullary tumor derived from neural crest = chromaffin cells

32
Q

What is a paraganglioma?

A

catecholamine secreting tumor arising from sympathetic paraganglion OR extra-adrenal pheochromocytomas

33
Q

What kind of hormones are secreted by paragangliomas?

A

often don’t secrete at all; if they do its NE

34
Q

What kind of hormones are secreted by pheochromocytomas?

A

NE and/or epi

b/c of high PNMT due to cortisol

35
Q

What is effect of pheochromocytomas?

A

triad: headache, sweating, palpitations in person with hypertension
- blanching
- tachycardia
- chest pain
- arrhythmia
- postural hypotension

36
Q

Which pheos are more likely to be malignant?

A
  • extra-adrenal [paraganglioma]
  • tumors > 6 cm
  • more dense = > 10 hounsfield units
37
Q

What percent of pheos are associated with familial cause?

A

> 25%

38
Q

How do you diagnose pheochromocytoma?

A
  • plasma free metanephrines

- 24 hr urine metanephrine

39
Q

What are metanephrines?

A

metabolites of catecholamines

40
Q

How do you localize where pheochromocytoma is secretin?

A

MRI T2 = lights up bright highly metabolically active tissue
PET scan
I-meta-iodobenyzlgunaidine [MIBG] scan

41
Q

What is adrenal incidentaloma?

A

adrenal mass > 1cm discovered during radiologic exam incidentally

> 4cm be suspicious of cancer

42
Q

What percent of adrenal incidentalomas are functional?

A

10-25%

43
Q

What hormone is primarily secreted by subclinical adrenal incidentalomas?

A

5-47% secrete cortisol

44
Q

What are the three Ps of MEN1?

A
  • pituitary tumor
  • parathyroid tumor
  • pancreatic endocrine tumors
45
Q

What are the 4 genetic syndromes associated with pheochromocytoma?

A
  • nerufibromatosis I
  • MEN 2a
  • MEN 2b
  • Von Hippel Lindau
46
Q

What causes Von Hippel Lindau?

A

inactivating mutation in VHL tumor suppressor gene

47
Q

What causes MEN1?

A

autosomal dominant deletion 11q13 = inactivation of tumor suppressor gene MENIN

48
Q

What causes MEN2?

A

activating RET-proto-oncogene mutation –> activation of receptor tyrosine kinase
autosomal dominant

49
Q

What kind of tumors associated with von hippel lindau?

A
  • pheochromocytoma

- renal cell carcinoma

50
Q

What is presentation of MEN2 syndromes?

A
  • pheochromocytomas
  • hyperparathyroidism [4 gland hyperplasia]
  • medullary cancer of thyroid
51
Q

What is unique to MEN2B clinical presentation?

A

marfanoid habitus
mucosal neuromas
ganglioneuromas

52
Q

What is presentation of MEN1?

A
  • pituitary tumors
  • pancreatic endocrine tumors [zollinger ellison or insulinoma or glucagonoma]
  • parathyroid tumors [hyperplasia]
53
Q

What causes neurofibromatosis 1?

A

mutation in gene encoding parafibromin = tumor suppresso

54
Q

What is presentation of neurofibromatosis I?

A
  • pheochromocytomas
  • skin neurofibromas
  • iris hamartomas
  • cafe au lait spots
55
Q

What is familial paraganglioma syndrome?

A

mutations in genes encoding succinate dehydrogenase complex –> uncouples mitochondrial e- transport and causes hypoxic state

have

  • pheochromocytomas
  • paragangliomas

can result in malignant and metastatic disease

56
Q

What percent of adrenal incidentalomas are malignant?

A

< 3%

57
Q

What is the differential diagnosis for bilateral adrenal tumors?

A
  • metastatic disease
  • congenital adrenal hyperplasia [CAH]
  • cortical adenomas
  • lymphoma
  • infeciton
  • hemorrhage
  • ACTH dependent cushing
  • pheo
  • amyloidosis
58
Q

What is BMAH?

A

bilateral macronodular hyperplasia –> causes metabolic syndrome and mild hypercortisolism

Endocrine (21 decks)

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