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

Endocrinology Part 3 (Adrenal Medulla) Flashcards

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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
Q

transported to a secretory vesicle via VMAT

A

EPI

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26
Q

event that occur inside the secretory vesicle

A

EPI is ready to be released by the cells through EXOCYTOSIS

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27
Q

how EXOCYTOSIS of EPI occur

A
  • Adhesion to cell membrane
  • Vesicle will form a vacuole to remove its content outside the cell (circulation)
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28
Q

% EPI bound to proteins in the circulation

A

50%

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29
Q

Ratio of catecholamines synthesis

A

NE:EPI = 9:1

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30
Q

aka Adrenal insufficiency

A

Addison’s disease

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31
Q

effect of Addison’s disease in normal ratio of catecholamines synthesis

A

Female = 45:1
Male = 24:1

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32
Q

reason why Addison’s disease has a significant ↑ in NE

A

↓ cortisol, ald.

cortisol is required by PNMT (responsible for NE → EPI)

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33
Q

T/F

Release of EPI by chromaffin cells is dependent on stimulation

Without stimulation/autonomous, it is prone to tachycardia & high BP

A

T

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34
Q

what happens to EPI when there is no stimulation?

A

catecholamines in the cytoplasm will be metabolized by catechol-O-methyltransferase (COMT)

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35
Q

EPI is metabolized by COMT into

A

metanephrines

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36
Q

NE is metabolized by COMT into

A

normetanephrines

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37
Q

DOP is metabolized by COMT into

A

methoxytyramine

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38
Q

metanephrines, normetanephrines, and methoxytyramine are all oxidized into? by what enzyme?

A

VMA

monoamine oxidase

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39
Q

T/F

metabolites of catecholamines are present in urine

A

T

40
Q

Catecholamine components found in URINE

A
  • VMA
  • Metanephrines
  • Free NE
  • Conjugated NE
41
Q

percentage of VMA in urine

A

30%

42
Q

percentage of metanephrines in urine

A

20%

43
Q

percentage of free NE in urine

A

5%

44
Q

percentage of conjugated NE in urine

A

8%

45
Q

98% NE are produced by

A

sympathetic ganglia

46
Q

2% NE are produced by

A

adrenal medulla

47
Q

Highest concentration is found in the brain

A

NOREPINEPHRINE

48
Q

Major form of catecholamine found in the body; not that hormonally active unlike EPI

A

NOREPINEPHRINE

49
Q

Metabolites of NE

A

3-methoxy-4-hydroxyphenylglycol (MHPG)

Vanillylmandelic acid (VMA)

50
Q

Metabolites of NE found in urine and CSF

A

3-methoxy-4-hydroxyphenylglycol (MHPG)

51
Q

Function of NE

A

Neurotransmitter for CNS and sympathetic nervous system

52
Q

Most abundant medullary hormone

A

EPINEPHRINE/ADRENALINE

53
Q

2 EPI sources:

A

Adrenal medulla
Norepinephrine (converted to EPI)

54
Q

Only comes from the adrenal

A

EPINEPHRINE/ADRENALINE

55
Q

Only released if there is any form of stress

A

EPINEPHRINE/ADRENALINE

56
Q

“Fight or Flight hormone”

A

EPINEPHRINE/ADRENALINE

57
Q

Mechanism why epinephrine is released during any form of stress

A

PNMT – cortisol dependent
↑ stress = ↑ stress hormone (CORTISOL)
↑ cortisol = ↑ PNMT (↑NE to EPI conversion)

58
Q

Potent catecholamine

A

EPI

59
Q

↑ glucose conc. by allowing glycogenolysis

A

EPI

60
Q

Specimen Collection for EPI

A

indwelling catheter (C-line, central venous catheter)
*no venipuncture

61
Q

result if venipuncture is used for EPI

A

false ↑ EPI (fear in needle → triggers EPI release)

62
Q

Major Metabolite of EPI

A

Vanillylmandellic acid (VMA)

63
Q

Major catecholamine metabolite

A

60% VMA

64
Q

Produced by decarboxylation of 3,4-dihyroxyphenylalanine (DOPA)

A

DOPAMINE

65
Q

Highest conc. is found in the regions of the brain

A

DOPAMINE

66
Q

Major intact catecholamine found in urine

A

DOPAMINE

67
Q

Metabolite of Dopamine

A

Homovanillic acid (HVA)

68
Q

Dusky tumor color after stained using chromium salt

A

Pheochromocytoma

69
Q

Tumor of adrenal medulla

A

Pheochromocytoma

70
Q

condition with overproduction of catecholamine

A

Pheochromocytoma

71
Q

Catecholamine-producing tumor arising from chromaffin cells (adrenal medulla)

A

Pheochromocytoma

72
Q

Causes of Pheochromocytoma

A

Limited degradation capacity
Limited storage for excess NE and metabolite

73
Q

Causes HTN with nonspecific signs and symptoms

A

Pheochromocytoma

74
Q

Fatal malignant condition in children resulting to excessive production of NE

A

Neuroblastoma/Paraganglioma

75
Q

aka Neuroblastoma

A

Paraganglioma

76
Q

Laboratory result in Neuroblastoma/Paraganglioma

A

High urine excretion of HVA, VMA, and dopamine

77
Q

LABORATORY ANALYSES FOR CATECHOLAMINES

A
  1. 24 Hr Urine Fractionated Metanephrines & Catecholamines
  2. Fractionated Free Plasma Metanephrines
  3. Total Plasma Catecholamines & Urine Metanephrines
  4. Clonidine Suppression Test
78
Q

Initial test performed for catecholamine det.

A

24 Hr Urine Fractionated Metanephrines & Catecholamines

79
Q

Best test (highly sensitive, highly specific) for catecholamines

A

24 Hr Urine Fractionated Metanephrines & Catecholamines

80
Q

Sensitivity and specificity of 24 Hr Urine Fractionated Metanephrines & Catecholamines

A

98%

81
Q

Sample used in 24 Hr Urine Fractionated Metanephrines & Catecholamines

A

24hr urine

82
Q

What are measured in 24hr urine Fractionated Metanephrines & Catecholamines

A

metanephrines
catecholamines

83
Q

Very sensitive test, poor specificity

A

Fractionated Free Plasma Metanephrines

84
Q

Sensitivity of Fractionated Free Plasma Metanephrines

A

96-100%

85
Q

Specificity of Fractionated Free Plasma Metanephrines

A

85-89%

86
Q

Special patient preparation for Fractionated Free Plasma Metanephrines

A

Supine for 30 mins. (before and during collection)

87
Q

Reason why upright posture (standing) is prohibited during Fractionated Free Plasma Metanephrines

A

activates sympathetic nervous system →
stimulates NE release and metabolism →
false ↑

88
Q

Most sensitive screening profile for catecholamines

A

Total Plasma Catecholamines & Urine Metanephrines

89
Q

value suggestive of catecholamine excess in Total Plasma Catecholamines & Urine Metanephrines

A

> 2000 pg/mL

90
Q

Test that differentiates pheochromocytoma from
neurogenic hypertension

A

Clonidine Suppression Test

91
Q

has ↑ catecholamine (↑ cardiac output and HTN) in CS test

A

Pheochromocytoma

92
Q

anti-hypertensive drug

A

Clonidine

93
Q

catecholamine antagonist

A

Clonidine

94
Q

example of Clonidine

A

Catapres

95
Q

Enumerate steps for Clonidine Suppression Test

A

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
Q

Normal result in Clonidine Suppression Test? Disease it indicate?

A

> 500 pg/mL ↓ in plasma catecholamine

Neurogenic HTN

97
Q

Abnormal result in Clonidine Suppression Test? Disease it indicate?

A

<500 pg/mL ↓ in plasma catecholamine (NO SUPPRESSION OCCURS)

Pheochromocytoma

Clinical Chemistry 2 - CEUMLS (9 decks)

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