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Clinical Chemistry 2 - CEUMLS > Endocrinology Part 3 (Adrenal Medulla) > Flashcards

Endocrinology Part 3 (Adrenal Medulla) Flashcards

1
Q

Inner adrenal gland

A

ADRENAL MEDULLA

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2
Q

Composed of chromaffin cells that secretes catecholamines

A

ADRENAL MEDULLA

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3
Q

derived from primordial neural crest

A

Chromaffin cells

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4
Q

Group of hormones synthesized by chromaffin cells of the adrenal medulla

A

Catecholamines

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5
Q

3 common catecholamines

A

o Norepinephrine
o Epinephrine
o Dopamine

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6
Q

Precursors for catecholamine production? identify if direct or indirect precursor

A
  1. Phenylalanine – indirect precursor
  2. Tyrosine – direct precursor
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7
Q

Catecholamines is named as “catecholamine” due to? explain.

A

structure

Catechol nucleus: benzene w/ 2 hydroxyl side grp
Amine side chain

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8
Q

Functions of Catecholamines

A
  • 1st responder to stress
  • Promotes fight-or-flight response
  • Increases cardiac output and blood pressure
  • Diverts blood toward muscle and brain
  • Mobilizes fuel from storage
  • Dilate pupils
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9
Q

fight-or-flight response function of catecholamine is due to

A

heightened body activity and strength
sharp thinking

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10
Q

Primordial Neural Crest during Early stage of gestation goes to

A

thoracic region

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11
Q

Primordial Neural Crest few weeks after early stage of gestation migrates to?

A

migrates to adrenal cortex to form adrenal medulla

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12
Q

2 cells that arises from primordial neural crest

A

Sympathogonia
Pheochromoblast

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13
Q

aka sympathetic ganglion cells

A

Sympathogonia

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14
Q

aka medulla chromaffin cells

A

Pheochromoblast

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15
Q

Tumors that can arise from Sympathogonia

A

Sympathoblasts

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16
Q
  • Childhood tumor; Rare in adolescence
  • Secretes HVA
A

Sympathoblasts

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17
Q

Example of Sympathoblasts

A

Malignant neuroblastoma/paraganglioma

Benign ganglioneuroma

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18
Q

Tumor that secretes catecholamine and has the ability to migrate
towards the aorta forming paraganglia

A

Pheochromocytoma

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19
Q

where phenylalanine → tyrosine → DOPA → dopamine takes place

A

Cytoplasm

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20
Q

transported to a lipid vesicle via vesicular monoamine transporter (VMAT)

A

Dopamine

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21
Q

event that occur inside the lipid vesicle

A

dopamine → norepinephrine

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22
Q

released from the lipid vesicle into the cytoplasm

A

Norepinephrine

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23
Q

enzyme that converts NE → EPI

A

phenylethanolamine N-methyltransferase (PNMT)

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24
Q

a cortisol dependent enzyme

A

phenylethanolamine N-methyltransferase (PNMT)

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25
transported to a secretory vesicle via VMAT
EPI
26
event that occur inside the secretory vesicle
EPI is ready to be released by the cells through EXOCYTOSIS
27
how EXOCYTOSIS of EPI occur
* Adhesion to cell membrane * Vesicle will form a vacuole to remove its content outside the cell (circulation)
28
% EPI bound to proteins in the circulation
50%
29
Ratio of catecholamines synthesis
NE:EPI = 9:1
30
aka Adrenal insufficiency
Addison’s disease
31
effect of Addison’s disease in normal ratio of catecholamines synthesis
Female = 45:1 Male = 24:1
32
reason why Addison’s disease has a significant ↑ in NE
↓ cortisol, ald. cortisol is required by PNMT (responsible for NE → EPI)
33
T/F Release of EPI by chromaffin cells is dependent on stimulation Without stimulation/autonomous, it is prone to tachycardia & high BP
T
34
what happens to EPI when there is no stimulation?
catecholamines in the cytoplasm will be metabolized by catechol-O-methyltransferase (COMT)
35
EPI is metabolized by COMT into
metanephrines
36
NE is metabolized by COMT into
normetanephrines
37
DOP is metabolized by COMT into
methoxytyramine
38
metanephrines, normetanephrines, and methoxytyramine are all oxidized into? by what enzyme?
VMA monoamine oxidase
39
T/F metabolites of catecholamines are present in urine
T
40
Catecholamine components found in URINE
* VMA * Metanephrines * Free NE * Conjugated NE
41
percentage of VMA in urine
30%
42
percentage of metanephrines in urine
20%
43
percentage of free NE in urine
5%
44
percentage of conjugated NE in urine
8%
45
98% NE are produced by
sympathetic ganglia
46
2% NE are produced by
adrenal medulla
47
Highest concentration is found in the brain
NOREPINEPHRINE
48
Major form of catecholamine found in the body; not that hormonally active unlike EPI
NOREPINEPHRINE
49
Metabolites of NE
3-methoxy-4-hydroxyphenylglycol (MHPG) Vanillylmandelic acid (VMA)
50
Metabolites of NE found in urine and CSF
3-methoxy-4-hydroxyphenylglycol (MHPG)
51
Function of NE
Neurotransmitter for CNS and sympathetic nervous system
52
Most abundant medullary hormone
EPINEPHRINE/ADRENALINE
53
2 EPI sources:
Adrenal medulla Norepinephrine (converted to EPI)
54
Only comes from the adrenal
EPINEPHRINE/ADRENALINE
55
Only released if there is any form of stress
EPINEPHRINE/ADRENALINE
56
“Fight or Flight hormone”
EPINEPHRINE/ADRENALINE
57
Mechanism why epinephrine is released during any form of stress
PNMT – cortisol dependent ↑ stress = ↑ stress hormone (CORTISOL) ↑ cortisol = ↑ PNMT (↑NE to EPI conversion)
58
Potent catecholamine
EPI
59
↑ glucose conc. by allowing glycogenolysis
EPI
60
Specimen Collection for EPI
indwelling catheter (C-line, central venous catheter) *no venipuncture
61
result if venipuncture is used for EPI
false ↑ EPI (fear in needle → triggers EPI release)
62
Major Metabolite of EPI
Vanillylmandellic acid (VMA)
63
Major catecholamine metabolite
60% VMA
64
Produced by decarboxylation of 3,4-dihyroxyphenylalanine (DOPA)
DOPAMINE
65
Highest conc. is found in the regions of the brain
DOPAMINE
66
Major intact catecholamine found in urine
DOPAMINE
67
Metabolite of Dopamine
Homovanillic acid (HVA)
68
Dusky tumor color after stained using chromium salt
Pheochromocytoma
69
Tumor of adrenal medulla
Pheochromocytoma
70
condition with overproduction of catecholamine
Pheochromocytoma
71
Catecholamine-producing tumor arising from chromaffin cells (adrenal medulla)
Pheochromocytoma
72
Causes of Pheochromocytoma
Limited degradation capacity Limited storage for excess NE and metabolite
73
Causes HTN with nonspecific signs and symptoms
Pheochromocytoma
74
Fatal malignant condition in children resulting to excessive production of NE
Neuroblastoma/Paraganglioma
75
aka Neuroblastoma
Paraganglioma
76
Laboratory result in Neuroblastoma/Paraganglioma
High urine excretion of HVA, VMA, and dopamine
77
LABORATORY ANALYSES FOR CATECHOLAMINES
1. 24 Hr Urine Fractionated Metanephrines & Catecholamines 2. Fractionated Free Plasma Metanephrines 3. Total Plasma Catecholamines & Urine Metanephrines 4. Clonidine Suppression Test
78
Initial test performed for catecholamine det.
24 Hr Urine Fractionated Metanephrines & Catecholamines
79
Best test (highly sensitive, highly specific) for catecholamines
24 Hr Urine Fractionated Metanephrines & Catecholamines
80
Sensitivity and specificity of 24 Hr Urine Fractionated Metanephrines & Catecholamines
98%
81
Sample used in 24 Hr Urine Fractionated Metanephrines & Catecholamines
24hr urine
82
What are measured in 24hr urine Fractionated Metanephrines & Catecholamines
metanephrines catecholamines
83
Very sensitive test, poor specificity
Fractionated Free Plasma Metanephrines
84
Sensitivity of Fractionated Free Plasma Metanephrines
96-100%
85
Specificity of Fractionated Free Plasma Metanephrines
85-89%
86
Special patient preparation for Fractionated Free Plasma Metanephrines
Supine for 30 mins. (before and during collection)
87
Reason why upright posture (standing) is prohibited during Fractionated Free Plasma Metanephrines
activates sympathetic nervous system → stimulates NE release and metabolism → false ↑
88
Most sensitive screening profile for catecholamines
Total Plasma Catecholamines & Urine Metanephrines
89
value suggestive of catecholamine excess in Total Plasma Catecholamines & Urine Metanephrines
>2000 pg/mL
90
Test that differentiates pheochromocytoma from neurogenic hypertension
Clonidine Suppression Test
91
has ↑ catecholamine (↑ cardiac output and HTN) in CS test
Pheochromocytoma
92
anti-hypertensive drug
Clonidine
93
catecholamine antagonist
Clonidine
94
example of Clonidine
Catapres
95
Enumerate steps for Clonidine Suppression Test
a. Stops antihypertensive drugs for 12 hrs b. Measure total plasma catecholamine c. Administer 0.3 mg Clonidine d. Repeat levels after 3 hours (measure total plasma catecholamine)
96
Normal result in Clonidine Suppression Test? Disease it indicate?
>500 pg/mL ↓ in plasma catecholamine Neurogenic HTN
97
Abnormal result in Clonidine Suppression Test? Disease it indicate?
<500 pg/mL ↓ in plasma catecholamine (NO SUPPRESSION OCCURS) Pheochromocytoma

Clinical Chemistry 2 - CEUMLS (9 decks)

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