14 15 Adrenal Cortex - Cushing Addison Flashcards Preview

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

Flashcards in 14 15 Adrenal Cortex - Cushing Addison Deck (72):
1

How is cortisol regulated? Describe the feedback loop

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

2

ACTH

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)

3

Can ACTH be used cross species

Yes

4

What species only use cortisol

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

5

What species uses cortisol and corticosterone

Dogs

6

What species use corticosterone

birds, rats, mice (rodents)

(NO cortisol)

7

What are some tissues that glucocorticoids affect

Metabolic, immune, blood, skeletal

8

What are the metabolic effects of glucocorticoids

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

9

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

glucose

10

What are the main functions of adrenocortical steroids

maintain blood glucose - hyperglycemic
promotion glycogen storage

11

what are the potencies of the corticoid hormones

cortisol 3x > corticosterone = aldosterone

(cortisol is the most potent)

12

What are some immune functions of glucocorticoids

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

13

How do glucocorticoids influence blood

increase neutrophils
decrease lymphocytes

14

How do glucocorticoids affect skeletal system

promote bone breakdown
Inhibits vit D

15

What does cortisol do at high level to T-lymphocytes

inhibit T-lymphocytes

16

What is the function of DHEA

primary androgen

17

What are the actions of DHEA and aldosterone?

- 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

18

What are the effects of mineralocorticoids / aldosterone

Promote Na retention and K elimination
Water retention
H ion elimination

19

What is an example of a mineralcorticoid

aldosterone (major one, lower species use others)

NOT regulated by the pituitary

20

What is another name for Hyperandrenocorticim

cushing syndrome

21

What is the most common cause of spontaneous Cushing

excessive ACTH production

22

where is Cushing syndrome most common

Older dogs
rare in cats

23

What is suppressed in animals with primary adenocortical tumors

ACTH and CRH

24

What is iatrogenic Cushings

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

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