Growth hormone Flashcards

1
Q

metabolic function of GH

A

promotes lipolysis and is counter-regulatory for hypoglycemia

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2
Q

mechanism of action

A

cytokine receptor activates JAK-STAT pathway

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3
Q

Laron’s dwarfism

A

inactivating mutation in GHR; treatment with IGF-1

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4
Q

direct actions of GH

A

opposes insulin, synergizes with cortisol

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5
Q

indirect actions of GH

A

dependent on IGF-1; IGF-1 has spillover with insulin and will activate insulin receptors (countering the effects of GH) at high enough levels

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6
Q

hypothal

A

positive: GHRH
negative: somatostatin

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7
Q

ant. pit.

A

40% of the cells here are somatotropes

release is pulsatile (more release during sleep)

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8
Q

feedback reg.

A

IGF-1 receptors at pituitary and hypothalamus

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9
Q

physiological stimulants of GH release

A

alpha-adrenergics; protein rich meal, hypoglycemia, stress, exercise, sleep

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10
Q

physiological inhibitors of GH

A

glucose, fatty acids and beta-adrenergics

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11
Q

acquired GH deficiency

A

traumatic brain injury, infection, iatrogenic (most common, esp. following resection)

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12
Q

genetic GH deficiency

A

defects in HESX1, PIT1, PROP1

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13
Q

clinical manifestations children (deficiency)

A

impaired growth; measured as >2 SD below normal, delayed bone age; hypoglycemia

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14
Q

clinical manifestations in adults (deficiency)

A

insidious, increased bone mass and adiposity

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15
Q

diagnosis of GH deficiency

A

based on provocative testing

arginine (protein load), clonidine (alpha agonist), insulin (induces hypoglycemia)

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16
Q

clinical manifestations children (excess)

A

gigantism, glucose intolerance

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17
Q

clinical manifestations adults (excess)

A

acromegally, arthralgias, glucose intolerance, hypertension

18
Q

diagnosis of GH excess

A

elevated IGF-1, oral glucose tolerance test (failure to respond is indicative of GH adenoma), MRI for adenoma,

19
Q

treatment for GH excess

A

transphenoidal surgery, or radiation + medical therapy if surgery is not successful

20
Q

somatropin indications

A

GH deficiency

stature conditions: (Turner syndrome, chronic renal disease)

21
Q

somatropin contraindication

A

any active malignancy

critically ill patients

22
Q

somatropin dosage

A

SQ injection @ bedtime; considerably higher dose than normal

23
Q

adverse effects somatropin children

A

headache, increased ICP, SCFE (all generally rare)

24
Q

adverse effects somatropin adults

A

edema, arthralgias, carpal tunnel syndrome (adjust levels to keep them healthy)

25
Mecasermin definition
IGF-1 recomb. SQ BID
26
Mecasermin indications
Laron's, STAT5b mutations, autoimmunity vs. GH
27
Mecasermin contraindications
active neoplasia, hypoglycemia
28
Mecasermin adverse effects
local hypoglycemia and lipohypertrophy at injection site; rarely SCFE and ICP
29
Mecasermin eval. of response to therapy
must monitor growth effect (IGF-1 levels not useful)
30
octreotide definition and structure
somatostatin analog for the suppression of GH release; 8 AA ring peptide with longer half life than somatostatin
31
octreotide dosage
not PO, every four weeks
32
octreotide indications
acromegally, portal HTN, hyperinsulinism (SST receptors @ beta cell block release)
33
octreotide adverse effect
gallstones/sludge, n/v, injection site discomfort
34
octreotide eval to therapy
symptom reduction, IGF-1 normalizing, GH levels should improve
35
Pegvisomant definition
PEGylated GH, occupies receptors, longer half-life and decreased antigenicity
36
Pegvisomant dosage
SQ
37
Pegvisomant indications
acromegally not surgically responsive
38
Pegvisomant adverse effects
hepatitis - monitor ALT, AST | tumor growth - loss of negative feedback
39
Pegvisomant eval
serum IGF-1 levels should be eval'ed
40
Dopamine agonists role in acromegally and names
paradoxical inhibition of GH by blocking co-secreting (somato/lactotrophic) adenomas; D2 receptors agonists - bromocriptine and cabergoline