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Adrenal gland Flashcards

1
Q

cellular zonation of adrenal cortex

A

zona glomerulosa - mineralcorticoids (aldosteron)
zona fasiculata - glucocorticoids (cortisone, corisol, corticosterone)
zona reticularis- sex hormones (androgens, estrogens)
chromaffin cells - catacholamines ( NE & EPI)

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2
Q

Adrenal gland general function

A

affect blood pressure & electrolytes within the blood

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3
Q

Adrenal regulation

A

hypothalamus - CRH
pituitary gland - ACTH
adrenal cortex- cortisol feedback loop

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4
Q

precursor for adrenal gland hormones

A

cholesterol!

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5
Q

cortisol feedback mechanism

A

hypothalamus –(CRH)–> anterior pituitary –(ACTH)–>adrenal cortex–> cortisol!
cortisol inhibits hypothalamus & anterior pituitary

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6
Q

zona glomerulosa (outer 10%)

A

mineralcorticoids
aldosterone - enzyme aldosterone synthetase active
stimulated by ACTH & renin axis system

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7
Q

zona faciculata (middle 75%)

A

glucocorticoids - cortisol, cortisone, DHEA

stimulated by ACTH

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8
Q

zona reticularis (inner 10%)

A

androgens like DHEA are sulfated to DHEAS (main androgen)

stimulated by ACTH

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9
Q

Renin-angiotensin system (RAS)

A

renin is released from kidney juxtaglomerulus apparatus
renin acts on angiotensin-ogen from liver to get angiotensin I
angiotensin I is converted by ACE (lung) to angiotensin II ( vasoconstrictor)

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10
Q

what does Renin-angiotensin system (RAS) lead to in the body?

A

aldosterone release from adrenal cortex & resulting absorption of Na+ from the proximal tubule of the kidney
& increase in osmotic pressure & improvement of blood pressure

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11
Q

cortisol general

A

made in F-zone w/ adequate 17-alpha-hydrolase activity
dinural variation - regulated by ACTH
90% protein bound (CBG)

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12
Q

cortisol effects

A 
stimulates gluconeogensis & glycogenesis
decreasing protein synthesis
increase blood glucose
decrease calcium absorption
increases adipose fat tissue
influences CNS pain perception & sense of well being
slows inflammatory response
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13
Q

cortisol & ATCH diurnal cycles

A

lowest at midnight & highest around 8 am

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14
Q

adrenal insufficiency labs show:

A

decreased cortisol
increased ACTH & CRH
the increased ACTH leads to adrenal gland hyperplasia & increased androgen production

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15
Q

Diseases associated with aldosterone

A

congenital adrenal hyperplasia
isolated hypoaldosteronism
hyperaldosteronism

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16
Q

diseases associated with cortisol

A

addison’s disease

cushings syndrome

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17
Q

Congenital adrenal hyperplasia

A

inherited family of enzyme disorders
lead to decreased cortisol & decreased aldosterone
defect in 21-hydroxylase enzyme & causes a build up of 17-hydroxy progesterone & androgens bc cortisol is low
treat with replacement cortisol

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18
Q

isolated hypoaldosteroneism

A

only aldosterone is decreased
see in adrenal gland destruction, chronic heparin therapy etc
patients with diabetes, mild metabolic acidosis, increased metabolic acidosis & elevated serum K+ with low urinary K+

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19
Q

hyperaldosteronism

A

excess aldosterone
may develop metabolic alkalosis, hyper-tension & increased serum K+
determine PA/PRA (plasma aldosterone/plasma renin activity)
PA/PRA >25 indicative for disease

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20
Q

urinary excretion of K+ suggests:

A

hyperaldosteronism

especially >30 mEq/L

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21
Q

upright PA/PRA ratio (>25)

A

hyperaldosteronism

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22
Q

no Captopril suppression suggests:

A

hyperaldosteronism

23
Q

Cortisol insufficiency

A

addisons disease
decrease cortisol w/ weakness, fatigue, anorexia, diarrhea, nausea
often 90% of cortex gland is destroyed

24
Q

lab values for addison’s disease

A

decreased Na+, glucose, cortisol
increased K+, ACTH, calcicum
prerenal azotemia
mild metabolic acidosis

25
causes of addisons
autoimmune (70%) | infections (tuberculosis 20%), hemorrhage, infiltrative processes, metastasis
26
cortisol insufficiency testing
when decreased cortisol w/ increased ACTH on 8 am specimen - need stimulation tests
27
Cosynthopin
stimulates both cortisol & aldosterone secretions | look for rise in cortisol when given 250 ug
28
Metyrapone
give at midnight, blocks 11-B-hydroxylase & look for rise in 11-DOC while cortisole decreases
29
normal response to cosynthopin but not to metyrapone?
look for secondary adrenal insufficiency (ACTH secreting tumor)
30
Addison's disease general
primary adrenal insufficiency - gradual destruction of adrenal gland 90% loss before symptoms secondary adrenal insufficiency- most common form of the disease; Lack of ACTH
31
Cushing's syndrome general
prolonged exposure to high levels of cortisol leads to glucose problems, immune suppression & depression high cortisol & low ACTH if primary
32
common causes of cushings
ACTH secreting pituitary adenoma (68%) autocortisol production by adrenal tumor (17%) excess ectopic ACTH or CRH production (15%)
33
Assay methods
2 site IRMA assay for ACTH | ELISA for cortisol
34
how to separate ACTH-dependent from ACTH-independent cushings syndrome
ACTH dependent cushings: ACTH >15 pg/uL & cortisol >15 ug/L
35
Cushing's syndrome symptoms
upper body obesity: round face, increased fat about neck, thinning of arms & legs fragile skin: easy bruising etc hypertension & diabetes (!!!)- secondary diabetic condition excess hair growth & fertility issues
36
Cortisol Suppression testing w/ Dexamethasone
differentiates between pituitary & ectopic ACTH secreting tumor pituitary is 90% suppressed but tumor is not!!
37
Cushing's lab testing
excess cortisol, LOSS OF DIURNAL VARIATION, resistance to suppression test urine free cortisol levels on 24 hr urine serum cortisol @ 8 am & 4 pm
38
DHEA & DHEAS
formed in zona reticularis (cholesterol based) & are precursors to number of androgens: androstenedione, testosterone, 5-dehydrotestosterone (5-DHT) & estrogens men get 5% of their testosterone from adrenal gland women get 40-65% of their testosterone from the adrenal gland
39
Androgen excess
overproduction can lead to infertility & masculization in women over production inhibits pituitary gonadotropin hormone production leading to loss on needed hormones
40
adrenal release of cortisol occurs when the pituitary releases?
ACTH
41
aldosterone is synthesized in the adrenal cortex layer____?
zona glomerulosa
42
Catecholamine synthesis location
adrenal medulla
43
Catecholamines (2)
epinephrine & norepinephrine
44
Epinephrine
made form tyrosine (!) increases cardiac output, blood pressure direct blood to muscles & brain mobilizes fuel from storage to action
45
rate of norepinephrine to epinephrine
9:1
46
enzyme that converts norepi to epi
phenylethanolamine N-methyl transferase or PNMT | this is the control point in epinephrine synthesis
47
epinephrine cell action
interacts with alpha-adrenergic receptors on cells that cause a cascade of events on the interior of the cell produce more ATP etc
48
Catecholamine degradation
3 mechanisms: 1. reuptake into secretory vesicles 2. uptake in nonneuronal cells (mostly liver) 3. degradation through 2 enzymes lead to formation of metanephrine & VMA from free catecholamines
49
2 enzymes that produce metanephrine & VMA from free catecholamines
catechol methyl transferase or COMT | monoamine oxidase MAO
50
methods of analysis of catecholamines
HPLC, fluorometric methods, or LC-MS/MS used for urinary 24 hr metabolites of catecholamines reliable & not altered by age/gender drugs can interfere with fluormetric methods color methods - test VMA special urine collection, NO BANANAS or VANILLA up to 3 days prior
51
causes of sympathetic hyperactivity
``` elevated epinephrine autonomic dysfunction panic attacks stress response drugs food with tyramine PHEOCHROMOCYTOMA ```
52
Pheochromocytoma
tumor of chromaffin cells | hypertension present, high levels of catecholamines & will NOT be suppressed by CLONIDINE
53
testing for pheochromocytoma
24 hr urine test for metanephrines (!) & catecholamines | clonidine (should suppress epinephrine) suppression test is 92% accurate

Clinical Chemistry (23 decks)

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