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Endocrine (updated 2016) > 14 15 Adrenal Cortex - Cushing Addison > Flashcards

14 15 Adrenal Cortex - Cushing Addison Flashcards

(72 cards)

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1
Q

How is cortisol regulated? Describe the feedback loop

A

1) Higher brain centers stimulate the hypothalamus to produce CRH
2) CRH > portal system to stimulate production of ACTH by the Anterior Pituitary
3) ACTH > blood stream and stimulates the inner zone of adrenal cortex to release cortisol
4) cortisol > blood stream to affect target cells/tissues and INHIBITS secretion of CRH and ACTH

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2
Q

ACTH

A

39 aa polypeptide (protein hormone)
postions 1-24 common to ACTH in ALL species
high species conservation

Stimulates growth and steroid production of zona fasiculata and reticualris of adrenal cortex

acts via cAMP (2nd messenger)

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3
Q

Can ACTH be used cross species

A

Yes

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4
Q

What species only use cortisol

A

Cats, primates, horses, domestic livestock species, other mammals

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5
Q

What species uses cortisol and corticosterone

A

Dogs

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6
Q

What species use corticosterone

A

birds, rats, mice (rodents)

NO cortisol

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7
Q

What are some tissues that glucocorticoids affect

A

Metabolic, immune, blood, skeletal

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8
Q

What are the metabolic effects of glucocorticoids

A 
Promotes gluconeogenisis
Stimulates lipolysis
promotes protein degradation
stimulates glycogen formation
inhibit glucose uptake by many tissues
highly catabolic for most tissues
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9
Q

What is the only substrate that the CNS can use for energy

A

glucose

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10
Q

What are the main functions of adrenocortical steroids

A

maintain blood glucose - hyperglycemic

promotion glycogen storage

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11
Q

what are the potencies of the corticoid hormones

A

cortisol 3x > corticosterone = aldosterone

cortisol is the most potent

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12
Q

What are some immune functions of glucocorticoids

A

Potent anti-inflammatory role (used clinically)
Immunosuppression (at higher doses)
Potential for infections

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13
Q

How do glucocorticoids influence blood

A

increase neutrophils

decrease lymphocytes

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14
Q

How do glucocorticoids affect skeletal system

A

promote bone breakdown

Inhibits vit D

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15
Q

What does cortisol do at high level to T-lymphocytes

A

inhibit T-lymphocytes

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16
Q

What is the function of DHEA

A

primary androgen

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17
Q

What are the actions of DHEA and aldosterone?

A
  • may play a role in development of secondary sexual characteristics at puberty
  • Substrates for estrogens
  • may play a role in the preventing degenerative changes in aging
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18
Q

What are the effects of mineralocorticoids / aldosterone

A

Promote Na retention and K elimination
Water retention
H ion elimination

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19
Q

What is an example of a mineralcorticoid

A

aldosterone (major one, lower species use others)

NOT regulated by the pituitary

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20
Q

What is another name for Hyperandrenocorticim

A

cushing syndrome

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21
Q

What is the most common cause of spontaneous Cushing

A

excessive ACTH production

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22
Q

where is Cushing syndrome most common

A

Older dogs

rare in cats

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23
Q

What is suppressed in animals with primary adenocortical tumors

A

ACTH and CRH

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24
Q

What is iatrogenic Cushings

A

Cushing disease induced by clinician as a secondary effect of another treatment

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25
What is the cause of iatrogenic Cushing
Exogenous glucocorticoids causing clinical signs of cortisol excess. Stop giving glucocorticoids Atrophy of zona fasiculata Adrenal suppression despite signs of cortisol excess
26
What are some clinical symptoms of Cushing
``` Polydipsia and polyuria - ~80% of dogs, most common symptom Hyperphagia Abdominal enlargement / pendulous abdomen alopecia muscle weakness / lethargy *symptoms not identical in all animals ```
27
How quick does Cushing progress
disease is slowly progressive
28
What are the catabolic effects of Cushing
``` Increase blood glucose Muscle wasting Thin skin truncal alopecia Decreased bone density ```
29
How do you diagnose Cushing
``` clinical symptoms Elevated cortisol - serum/plasma - urinary ACTH challenge - patients have increased capacity to make cortisol low dose Dexamethasome test (DEX) ```
30
What are two types of Cushing
1) Pituitary-dependent hyperandrenocorticism (PDH) - more common in smaller dogs 2) Primary hyperandenocorticism / adrenocortical tumors - equally common in both large and small breeds
31
What is Pituitary-dependent hyperandrenocorticism (PDH)
secondary Cushing increased ACTH production most common (80%)
32
Primary hyperadrenocorticism is caused by
adrenal tumors
33
What is a low dose dexamethasone (DEX) test
can be used to diagnose If animal has Cushing Normal animal : low dose DEX suppresses ACTH and secondary cortisol Abnormal animal: low dose DEX does NOT suppress cortisol in animal with 1' or 2' Cushing *does NOT distinguish 1' vs 2' Cushing
34
What doesn't low dose DEX determine
difference between tumor (1') and PHD (2') Cushing
35
What does High-dose DEX test do
Suppress cortisol levels in PDH patients cortisol levels NOT suppressed in patients with adrenal tumors
36
What will ACTH levels be in dogs with PDH
ACTH is elevated in PDH
37
What will ACTH levels be in dogs with adrenal tumors
ACTH is surpressed in adrenal tumors
38
What is the most common treatment of PDH (2' Cushing)
Lysodren
39
What does Lysodern do to treat PDH
- concentrated in adrenal cortex; mechanism of action unknown - Selective necrosis of zona fasiculata and reticularis - overdose can cause hypoadrenocorticism and/or destroy zona glomerulosa
40
What would happen if you gave too much Lysodren to a dog
cause hypoadrenocorticism
41
What is Addison disease
Hypoadrenocorticism: adrenal cortical insufficiency uncommon in dogs, rare in cats symptoms: weight loss, lethargy, dehydration can be 1' or 2'
42
What is difference between primary and secondary diseases treatments in Addison and Cushing disease
Cushing- treated the same | Addison- different treatments
43
What do you use to diagnose secondary Addison
ACTH
44
What is the most common cause of primary adrenocortical failure
Autoimmune
45
What is an important cause of secondary Addison
Iatrogenic (caused by clinician)
46
How long does it take for ACTH to recover
months
47
What is the treatment of primary Addison
Saline to combat dehydration followed by glucocoriticoids and mineral corticoids
48
What is the treatment for secondary Addison
Glucocorticoid treatment (no need for mineralcoritoids) and identification of the underlying lesion
49
What does the zona glomerulosa produce
Aldosterone
50
What are the layers of the adrenal gland from the outside in?
``` Capsule Cortex - glomerulosa - fasiculata - reticularis Medulla ```
51
What hormone is produced in the adrenal cortex zona glomerulosa?
aldosterone
52
What hormones are produced in the adrenal cortex fasciculata / reticularis?
cortisol corticosterone DHEA Androstenedione
53
What is the major glucocorticoid in most animals?
cortisol
54
How is ACTH produced?
protein hormone produced by the anterior pituitary from a pro-opiomelanocortin molecule via proteolytic processing: signal sequence + pre-pro-oprionmelanocortin pro-opiomelanocortin (gets cleaved) ACTH + (β-lipotropin) ACTH + (𝛾-lipotropin + β-endorphin)
55
What external factors can influence corticoids
diurnal variation | stress
56
What are the general physiologic functions of glucocorticoids
metabolic response to stress immune blood skeletal
57
What are some hormones that are hyperglycemic?
glucocorticoids growth hormone epinephrine
58
What is the functional value of glucocorticoids
rise in glucocorticoids during periods of reduced food availability will help to maintain serum glucose concentrations for CNS function at the expense of fat and protein
59
What is the effect of glucocorticoids on the immune system?
``` inhibit the immune system - inhibit inflammation (phospholipase) - inhibit T-lymphocytes (cell-mediated immunity) - dose-dependent replacement physiological dose antiinflammatory dose immunosuppressive dose ```
60
How does stress affect glucocorticoids?
long term stress response - proteins and fats converted to glucose or broken down for energy - increased blood sugar - suppression of immune system
61
What sex steroids are produced by the zona fasciulata / reticularis?
DHEA Androsteinedione a precursor molecule to testosterone which in turn a is precursor to the estrogens
62
What is Spontaneous Cushing?
most commonly (80%) due to excessive ACTH production (2') pituitary-dependent hyperadrenocorticism can also arise from primary (1') adrenocortical tumors - can be adenomas or carcinomas - both ACTH and CRH suppressed in animals w/ 1' tumors
63
What is Primary hyperandenocorticism
primary Cushing caused by adrenal tumors can be carcinomas or adenomas
64
Differentiating Primary and Secondary Cushing
abdominal ultrasound normal adrenals: PDH secondary Cushing adrenal tumor: primary Cushing
65
How do you treat Primary Cushing / Adrenal Tumors
adrenalectomy is treatment of choice ~50 of tumors malignane Ketoconazole or Triostane to suppress cortisol is a non-surgical alternative Lysodren can be used to chemoblate the tumor
66
What is primary Addison (hypoadrenocorticism) disease? How is it diagnosed?
``` decreased glucocorticoids cause lethargy and weakness critical symptoms (dehydration) due to lack of mineral corticoids ``` diagnosis: hypoatremia, hyperkalemia
67
What is secondary Addison (hypoadrenocorticism) disease? How is it diagnosed?
naturally occurring disease (rare) - reduced secretion of ACTH by pituitary or CRH secreted by hypothalamus iatrogenic diagnosis: measure ACTH, cortisol measurement ACTH, cortisol after ACTH administration
68
etiology of hypoadrenocorticism
loss of 85-90% of adrenocortical cells required before clinical symptoms appear 1' adrenocortical failure-most common - frequently autoimmune 2' adrenocortical failure
69
iatrogenic hypoadrenocorticism
lack of stimulation to the adrenals cause long term atrophy - long-term exogenous glucocorticoid administration abrupt cessation of glucocorticoid admin → inability of adrenals to supply body's needs → signs of deficiency recovery is slow (months)
70
What is Equine Cushing or pituitary pars intermedia dysfunction (PPID)
results from tumor producing excessive amounts of ACTH in the pars intermedia (middle region of pituitary) symptoms: same as in canine Cushing plus long wavy hair that doesn't shed and laminitis
71
How to you diagnose Equine Cushing
low dose dexamethasone test | elevated ACTH
72
How do you treat Equine Cushing
pergolide (Prasend) - dopamine agonsit also used to treat Parkinson's disease in humans not curative

Endocrine (updated 2016) (19 decks)

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