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LAMP > Adrenal > Flashcards

Adrenal Flashcards

1
Q

What three layers make up the adrenal cortex?

A

zona glomerulosa
zona fasciculata
zona reticularis

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2
Q

zona glomerulosa

A

mineralcorticoids

aldosterone

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3
Q

zona fasiculata

A

glucocorticoids

cortisol

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4
Q

zona reticularis

A

sex steroids: progesterone, androgens, estrogen precursors

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5
Q

What is the primary mineralcorticoid and what does it do?

A

Aldosterone

Na and K homeostasis

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6
Q

What is the most important glucocorticoid and what does it regulate?

A

Cortisol

cardiovascular, metabolic, immunologic, homeostatic

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7
Q

What are the primary sex steroids?

A

androgens

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8
Q

What are hte primary catecholamines secreted from the adrenal cortex?

A

epi, norepi

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9
Q

What stimulates the movement of cholesterol into the mitochondria where CYP enzymes

A

ACTH

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10
Q

38 year old female presents to the emergency room saying her heart keeps “racing”
• Patient also reports that she is sweating profusely and has a severe headache
• Patient is monitored in the ED
– Frequent paroxysms of tachycardia with episodic hypertension exceeding 180/100 mm Hg

What is in the differential diagnosis for paroxysmal HTN?

A 
– Pheochromocytoma
• 2 – 8 cases/million people annually
• Only 1/300 patients evaluated for pheo end up with a confirmed diagnosis
– Labile hypertension – Panic disorder
– Hyperthyroidism
– Drugs
– Pseudopheochromocytoma
• When cause remains unknown
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11
Q

What is the classic triad of symptoms in patients with a pheochromocytoma?

A
  • Sustained or paroxysmal hypertension
  • Headache
  • Generalized sweating
  • Due to the generic nature of these symptoms and the rarity of pheos, only 1 in 300 patients evaluated for pheo end up with a confirmed diagnosis
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12
Q

What laboratory tests should be ordered to confirm a diagnosis of pheochromocytoma?

A 
Three tests:
– 24hoururinefractionated
metanephrines
– 24hoururinecatecholamines
– Plasma free fractionated metanephrines
• Specificity felt to be lower than urine tests (thus more false positives)
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13
Q

What are metanephrines and why are they elevated in pheochromocytoma?

A

• Pheos are catecholamine‐ secreting tumors that arise from the adrenal medulla
• NE and Epi are metabolized to normetanephrine and metanephrine intratumorally
– Pheos contain high level of COMT
• Metanephrines spill into plasma and are excreted in excess in urine

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14
Q

Why is measurement of urine metanephrines preferred over measurement of plasma or urine catecholamines?

A

Intratumoral metabolism of catecholamines occurs continuously and independently of catecholamine release
– Consistently elevated level of metanephrines

• Catecholamine release may occur intermittently or at low
rates
• Supported by studies that show elevated metanephrines change negligibly during paroxysms, while catecholamine levels change dramatically during paroxysms
• Additionally, metanephrine levels have been shown to correlate with tumor size whereas catecholamine levels do not
• That being said, 24 hour urine catecholamine measurement is part of the diagnostic algorithm because a 24 hour collection removes some of the element of variability that would be seen in a one time plasma measurement

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15
Q

Why are urine homovanillic acid (HVA) and vanillylmandelic acid (VMA) measured for diagnosis of neuroblastoma, and not metanephrines, since it is also a catecholamine‐secreting tumor?

A

• Neuroblastomas originate from sympathetic ganglion cells
– Contain MAO but not COMT
• Produce norepinephrine and dopamine
– Lack PNMT so no epi
• Intratumoral inactivation of NE and dopamine leads to HVA and VMA accumulation

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16
Q

Why aren’t urine HVA and VMA used for the diagnosis or monitoring of pheochromocytoma?

A
  • Dopamine‐producing pheos rare so HVA not elevated
  • Pheos do contain MAO but at lower levels than COMT
  • DHPG and MHPG are produced by pheos and converted to VMA
  • However, the increase in VMA levels is obscured by the baseline production of VMA from metabolism of sympathetic nerve norepinephrine, thus making VMA an insensitive marker of pheos
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17
Q

• 78 year old man presents to an outside hospital with hematuria and urinary retention
• Transferred to UMMC with urosepsis
• Physical exam:
– Height 5’2”
– Scrotal sac empty with no palpable testes

CT scan of abdomen & pelvis
• Enlarged uterus with large fibroid obstructing the bladder
• 3.8 cm cyst in the left adnexa possibly arising from an ovary
• Bilaterally enlarged adrenal glands

Lab results:
Elevated ACTH, 17-Hydrogxyprogest, androstendione, DHEAS

What is the most likely diagnosis in this case?

A

Congenital Adrenal Hyperplasia

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18
Q

What enzyme is most likely defective in this case?

A
  • 21 hydroxylase deficiency accounts for > 95% of congenital adrenal hyperplasia cases
  • 1 in 10,000 to 18,000 live births
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19
Q

21 hydroxylase def leads ot the accumulation of…

A

progesterone
17 hydroxy progesterone

Everything is shunted to the androgen biosynthetic pathway that is unaffected by the block (there is decreased/NO cortisol production)

20
Q

What is the effect of exccess androgens?

A

prenatal masculinization (ambiguous genitailia) in females and postnatal virilization in both sexes

21
Q

Is this case most likely due to partial or complete deficiency of 21‐hydroxylase?

A 
Simple virilizing (our case):
– Mild form, only partial deficiency
– Increase in ACTH is able to keep cortisol at NORMAL LEVELS
– 17‐OHP in excess causes mild salt‐losing leads to up‐regulation of aldosterone
– Aldosterone may actually be INCREASED in these patients
22
Q

What are the clinical and laboratory differences in patients with partial or complete 21‐hydroxylase deficiency?

A 
Salt‐losing:
– Severe form, complete deficiency
– Increase in ACTH has no effect on enzyme since it is non‐ functional
– LOW/NO aldosterone and cortisol
– Dehydration due to salt wasting
23
Q

A baby girl is born at 38 1/7 weeks with ambiguous genitalia.
Pertinent labs:
17‐hydroxyprogesterone: 32,710 ng/dL (<630)
Testosterone: 1449 ng/dL (20‐80) Plasma renin: 74.25 ng/ml/60 min (2.0‐35.0)
How confident are you in the diagnosis? What test(s) should be ordered next?

A

• Very high 17‐hydroxyprogesterone is
diagnostic for 21‐hydroxylase deficiency
• Virtually all affected patients present with
levels > 3500 ng/dl
– Diagnosis considered “highly probable” if > 10,000 ng/dL
• Order sodium and potassium!! – Want to avoid an adrenal crisis

24
Q

What are the electrolyte abnormalities that can occur in classic congenital adrenal hyperplasia (21‐hydroxylase deficiency)?

A
  • Hyponatremic, hypochloremic, hyperkalemic acidosis

* Due to aldosterone deficiency

25
Q

What’s considered the gold standard for diagnosing congenital adrenal hyperplasia?

A

ACTH (cosyntropin) stimulation test

26
Q

What is the second most common cause of CAH and what laboratory findings would be expected?

A

11‐beta hydroxylase deficiency

27
Q

How do you diagnose 11‐beta hydroxylase deficiency?

A

elevated 11‐beta hydroxylase levels

28
Q

How is 11‐beta hydroxylase deficiency similar to 21 hydroxylase def?

A

Ambiguous genitalia in females due to androgen

excess

29
Q

How does 11‐beta hydroxylase deficiency differ from 21 hydroxylase def?

A

– Hypertension due to 11‐deoxycortisone’s action as a mineralocorticoid
– Results in low renin which may result in hypokalemia

30
Q

30 year old female presents with complaints of weight gain

• Patient also complains of fatigue, moodiness, and says she is having relatively new issues with facial hair

Physical exam:
– Hirsutism noted
– BP: 180/110
– Bilateral pedal edema

What are the common signs and symptoms of hypercortisolism (Cushing’s syndrome)?

A 
Centripetal obesity
Facial plethora
Glucose intolerance
Weakness/proximal myopathy
Hypertension
Psychological changes
Easy bruisability
HIrsutism
31
Q

Why do patients with Cushing’s syndrome become hypertensive?

A
  • Cortisol and aldosterone have the same in vitro affinity for the mineralocorticoid receptor (MR)
  • 11‐hydroxysteroid dehydrogenase type 2 normally inactivates cortisol preventing its action at the MR
  • With cortisol excess, enzyme is overwhelmed and excess cortisol activates MR leading to Na retention and hypertension
32
Q

What three tests are recommended options to screen for Cushing’s syndrome?

A
  1. 24 hour urinary cortisol
    – 2 measurements to confirm diagnosis
    – Serum ACTH and cortisol are secreted in discrete bursts so measurement not helpful
  2. Latenightsalivarycortisol
    – Measured at bedtime or between 2300 and 0000 h
    – 2 measurements to confirm diagnosis
  3. Overnightlowdosedexamethasonesuppression test
    – Administer dexamethasone between 2300 and 0000 h
    – Measure serum cortisol between 800 and 900 h
33
Q

What is in the differential diagnosis for Cushing’s syndome?

A

ACTH dep Cushings syndrome (cushings disease, ectopic ACTH syondrome, ectopic CRH syndrome)
ACTH indep Cushings Syndrome (adrenal adenoma/carcinoma, micro/macronodular hyperplasia)
Pseudo Cushings syndrome (MDD, alcoholism)

34
Q

How is the low dose dexamethasone test performed and interpreted?

A

Dexamethasone INHIBITS pit ACTH secretion

LOW DOSE: overnight screening (1 mg dose)

  • can perform a 2 day test w/ 2 mg dose
  • Cushings syndrome pts will generally NOT suppress cortisol below 1.8-2 mcg/dL
  • however sutdies have shown that there are some cushings that DO suppress so anohter test must be used to confirm the diagnosis
35
Q

What is the high dose dexamethasone suppression test, and what is it used for clinically?

A

– OVernight or 2 days (8 mg doses)
– Used to differentiate Cushing’s disease from Cushing’s syndrome
– ACTH secretion in Cushing’s disease is only relatively resistant to dex suppression
– ThereforeinCushing’sdiseaseitwillNOTsuppressatlowdosebutWILL suppress at high dose
• Cushing’s disease (pit adenoma) patients will generally suppress to < 5.0 mcg/dL serum cortisol
• Normal patients will suppress to undetectable cortisol levels
– Incontrast,mostnonpituitarytumorswillnotsuppresswitheitherlowor high dose

36
Q

Why is dexamethasone used in the suppression test and not other steroids?

A

• Measurement of cortisol is unaffected by dexamethasone
• Several other steroids cross‐react with cortisol assays and would give falsely elevated cortisol results
• Can measure serum dexamethasone when performing suppression tests
– Verify compliance
– Verify adequate blood levels obtained from dose

37
Q

Once Cushing’s syndrome has been confirmed, how do you establish the cause?

A
  • Measurementof ACTH on 2 separate days recommended due to episodic nature of secretion
  • CRH = corticotropin releasing hormone test
  • IPSS = inferior petrosal sinus sampling
38
Q

12 year old girl presents for outpatient follow‐up after a recent hospitalization for severe vomiting requiring rehydration
• PMH:
– Diagnosed with celiac disease at age 8
– Total of 3 hospitalizations for vomiting in the last 16 months – History of anxiety and depression
• ROS:
– Severe irritability, hypersomnia
– Stomachaches, dizziness, anorexia with significant weight loss – Severe fatigue
– Muscle and joint pain

What are the common signs and symptoms of chronic adrenal insufficiency (Addison’s disease)?

A 
weakness, tiredness, fatigue
anorexia
GI sxs
Salt craving
postural dizziness
muscle/joint pain
39
Q

What findings are helpful for distinguishing primary adrenal insufficiency from secondary or tertiary adrenal insufficiency?

A

• Hyperpigmentation secondary to elevated ACTH
– Seen in primary adrenal insufficiency (not secondary or tertiary)
– Due to increased pro‐opiomelanocortin, a prohormone that is cleaved to biologically active ACTH, MSH, and others
– Elevated MSH leads to increased melanin synthesis
– Most conspicuous in areas exposed to light or friction
– Will fade with adequate therapy
• Mineralocorticoid deficiency not present in secondary/tertiary adrenal insufficiency
– Aldosterone preserved, and can be stimulated by intact renin‐angiotensin system
– As a result, will not see hyponatremic hyperkalemic hypotension

40
Q

What are the causes of adrenal insufficiency in children?

A

Primary (CAH, abnormal adrenal deve, autoimmunity, infection, drugs)

Secondary (Pituitary!)

Tertiary (hypothalamus)

41
Q

What laboratory tests are used to establish a diagnosis of adrenal insufficiency?

A

First step: measure a random 8 am serum cortisol and ACTH

If abnormal…

Second step: ACTH stimulation test
– Measure serum cortisol at baseline and 30 and 60 minutes after IV injection of cosyntropin (synthetic ACTH)
– Normal response is considered a minimum serum cortisol value of 18‐20 mcg/dL before or after ACTH injection

Third step: test to evaluate hte underlying cause

42
Q

Our patient had the following results:
Serum cortisol: < 0.3 mcg/dL (5‐25) Serum ACTH: 2069 pg/mL (≤ 46 pg/mL)
ACTH stimulation test:
Baseline, 30 min and 60 min serum cortisol: < 0.3 mcg/dL (5‐25)
Does she have primary, secondary or
tertiary adrenal insufficiency? What
additional tests should be performed?

A

Primary adrenal insufficiency

43
Q

How do you evaluate for pimary adrenal insufficiency?

A

– Measure anti‐adrenal antibodies
– If CAH is suspected measure adrenal androgens
• Unlikely in this case given later age of presentation and lack of virilization
– If negative, screen for TB, adrenoleukodystrophy, adrenomyeloneuropathy, adrenal hypoplasia congenita

44
Q

What is autoimmune adrenal insufficiency?

A

found with high anti-21-hydroxylase antibodies present

– In adults, accounts for 70‐90% of adrenal
insufficiency cases
– In the 1800s when Addison’s disease was first described, bilateral adrenal destruction by TB was most common cause
– Anti‐21‐hydroxylase is present in serum of 86% of affected patients

45
Q

In patients diagnosed with autoimmune

adrenal insufficiency, what other clinical issues should the physician be concerned about?

A

50‐65 % of patients with autoimmune adrenal insufficiency have one or more other autoimmune endocrine disorders
– Combination of autoimmune adrenal insufficiency and other autoimmune endocrine disorders known as polyglandular autoimmune syndromes types I and II
– If you recall, the patient has a known diagnosis of celiac disease which is associated with autoantibodies
• Patients with celiac disease had an 11x increased risk for adrenal insufficiency in a Swedish study

46
Q

Additional testing: – Glucose normal
– TSH: 9.64 U/L (0.7‐5.7) – FT4: 1.25 ng/dL (0.8‐1.9)

indicating a diagnosis of…

A

polyglandular autoimmune syndrome type II

LAMP (16 decks)

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