Clin Path - Adrenocortical Function

Front 1

Describe the normal activity of the Adrenocortical system in releasing cortisol

Back 1

-Hypothalamus releases CRH
-CRH causes production and release of ACTH from pituitary
-ACTH stimulates production and release of cortisol and aldosterone from the adrenal gland cortices
-Inc. cortisol causes neg. feedback on the release of CRH and ACTH

Front 2

Describe the normal activity of the Adrenocortical system in releasing Aldosterone

Back 2

-Inc. [Angiotensin II], hyperkalemia, hyponatremia, inc. [ACTH] promote release of Aldosterone from adrenal gland cortices
-Aldosterone stimulates the renal retention of Na+ & Cl- and excretion of K+ and H+
-Aldosterone release is inhibited by Atrial natriuretic peptide

Front 3

CRH
-define

Back 3

-corticotropin-releasing hormone

Front 4

ACTH
-define

Back 4

-Adrenocorticotropic hormone

Front 5

Aldosterone release
-promoters
-inhibitors

Back 5

Promoters:
-Angiotensin II
-Hyperkalemia
-Hyponatremia

Inhibitors:
-Atrial natriuretic peptide

Front 6

Main Adrenocortical hormones

Back 6

-Cortisol
-Aldosterone
-Progesterone
-Cholesterol

Front 7

Hyperadrenocorticism
-aka

Back 7

-Cushings

Front 8

Hyperadrenocorticism
-types

Back 8

-pituitary dependent hyperadrenocorticism
-functional adrenocortical neoplasm
-stress-induced adrenocortical hyperplasia

Front 9

Hypoadrenocorticism
-aka

Back 9

-Addisons

Front 10

Iatrogenic
-define

Back 10

-related to the actions of a medical person

Front 11

Hypercorticolemia
-caused by

Back 11

Spontaneous conditions:
-pituitary dependent hyperadrenocorticism
-functional adrenocortical neoplasm
-stress-induced adrenocortical hyperplasia

Iatrogenic conditions:
-Exogenous ACTH administration

Front 12

Pituitary-dependent hyperadrenocorticism (PDH)
-pathogenesis

Back 12

-Pituitary neoplasm
--ACTH production
---adrenocortical hyperplasia
----inc. Cortisol production

Front 13

Function Adrenocortical Neoplasia (FAN) causing hyperadrenocorticism
-pathogenesis

Back 13

-Neoplastic adrenocortical cells
--inc. cortisol production

Front 14

Stress-induced Hypercortisolemia
-pathogenesis

Back 14

-stress stimulated hypothalamus to release CRH
--CRH stimulates Pituitary release of ACTH
---Adrenocortical hyperplasia
----Inc. cortisol production

Front 15

Primary hypoadrenocorticism
-due to

Back 15

-bilateral adrenocortical hypoplasia

Front 16

Primary hypoadrenocorticism results in

Back 16

-dec. cortisol production
-dec aldosterone production --> electrolyte changes (loss of Na+ and Cl- & retention of K+ and H+)

Front 17

Iatrogenic hyperadrenocorticism
-drugs used

Back 17

Steroids
-prednisone
-prednisolone

Front 18

Iatrogenic hyperadrenocorticism
-main effects

Back 18

-Cushings like syndrome from continued glucocorticoid effects on the system, but bilateral adrenocortical hypoplasia from suppression of CRH and ACTH production
-Still have electrolyte balance (Na+, Cl- retention and H+, K+ excretion)

Front 19

Iatrogenic hypoadrenocorticism
-due to

Back 19

-abrupt cessation of steroid treatment
-ACTH is being produced but because of the bilateral adrenocortical hypoplasia from the initial iatrogenic treatment, minimal cortisol and aldosterone are being produced

-loss of renal electrolyte balance

Front 20

Drug that can result in iatrogenic hypoadrenocorticism
-purpose for use

Back 20

-Mitotane

-adrenolytic agent used to selectively destroy adrenocortical cells when an adrenal neoplasm is present

Front 21

Why is the Urinary Cort:Crt ratio of use?

Back 21

-amount of creatinine excreted per day is constant, so any increase in the ratio represents and increase in cortisol excretion

Front 22

What is important to know about the units used in the urinary Cort:Crt ratio?

Back 22

-cortisol measured in nmol/L
-creatinine measured in mmol/L

so

ratio of "20" means 0.000020

Front 23

Urinary Cort:Crt ratio
-if WRI
-if high

Back 23

-WRI: does not have hyperadrenocorticism

-High: may or may not have hyperadrenocorticism

Front 24

Inc. urinary Cort:Crt ratio in a PU/PD with suspect cushings
-interpretation

Back 24

-if WRI: probably not cushnoid
-if inc.: unknown

Front 25

Hyperadrenal diseases to expect
-high [ACTH]
-low [ACTH]

Back 25

High:
-PDH
-Primary hypoadrenocorticism

Low:
-FAN

Front 26

Why does measurement of ACTH have limited use in dogs and cats?

Back 26

-expensive
-unstable

Front 27

[ACTH] measurement can be used to differentiate..

Back 27

-PDH from FAN

Front 28

If an dog is cushnoid with dec. [ACTH] then....

Back 28

-FAN

Front 29

If and dog is cushnoid with inc. [ACTH] then...

Back 29

-PDH

Front 30

If dog is Addisonian with dec. [ACTH] then...

Back 30

-secondary hypoadrenocorticism (rare)

Front 31

If dog is Addisonian with no dec. [ACTH] then...

Back 31

-Primary hypoadrenocorticism

Front 32

If cat is Cushnoid with dec. [ACTH] then...

Back 32

-FAN

Front 33

If cat is cushnoid with no dec. [ACTH] then ...

Back 33

-PDH

Front 34

If cat is Addisonian with inc. [ACTH] then...

Back 34

-primary hypoadrenocorticism

Front 35

LDDST
-define

Back 35

-Low-dose dexamethasone suppression test

Front 36

LDDST
-procedure

Back 36

-take a pre-dexamethason sample for [cortisol]
-give dexamethasone IV
-at 4 & 8 hrs later take sample for [cortisol]

Front 37

LDDST
-expected results for a healthy animals
-why

Back 37

-dec. cortisol (<1.4 ug/dL)
-all suppress

-suppression of CRH and ACTH

Front 38

LDDST
-expected results for dogs with PDH

Back 38

-most with no suppression in [cortisol] (72%)

-some become suppressed then escape

Front 39

LDDST
-expected results for dogs with FAN

Back 39

-no suppression in [cortisol] (100%)

Front 40

LDDST
-expected results for dogs with nonadrenal (stress induced) hypercortisolemia

Back 40

-most suppress

-many do not suppress

Front 41

HDDST
-define

Back 41

-high-dose dexamethasone suppression test

Front 42

HDDST
-expected results for healthy dogs

Back 42

-suppression

Front 43

HDDST
-expected results for dogs with PDH

Back 43

-most suppression

-some don't suppress

Front 44

HDDST
-expected results for FAN

Back 44

-no suppression

Front 45

HDDST
-expected results for non-adrenal (stress) disorders

Back 45

-expect suppression

Front 46

Conditions that may show suppression by LDDST

Back 46

-healthy
-Non-adrenal (stress)

Front 47

Conditions that may show suppression by HDDST

Back 47

-Healthy
-PDH
-Non-adrenal (stress)

Front 48

Cortisol half-life

Back 48

- <2 hrs

Front 49

Differentials for non-suppressed LDDST and non-suppressed HDDST

Back 49

-FAN
-PDH

Front 50

Differentials for non-suppressed LDDST & suppressed HDDST

Back 50

-PDH
-Non-adrenal disease


-NOT FAN

Front 51

Differentials for an LDDST that is suppressed and escapes, and a suppressed HDDST

Back 51

-PHD
-Non-adrenal disease

-NOT FAN

Front 52

Differentials for suppressed LDDST and suppressed HDDST

Back 52

-Healthy
-Non-adrenal

NOT FAN
Probably not PDH

Front 53

Types of abnormal adrenal glands and their responses to exogenous ACTH

Back 53

-hyperplastic glands: exaggerated response
-neoplastic glands: some normal, some exaggerated, some with no response
-hypoplastic glands: no response

Front 54

ACTH Stimulation test
-procedure

Back 54

-take pre-ACTH sample to check [cortisol]
-give ACTH
-take post-ACTH sample (1-2 hrs) to check [cortisol]

Front 55

ACTH Stimulation test
-healthy dog expected results

Back 55

-inc. cortisol production ( < 17 ug/dL)

Front 56

ACTH Stimulation test
-PDH expected results

Back 56

-exaggerated response

Front 57

ACTH Stimulation test
-FAN expected results

Back 57

-1/2 responsive
-1/2 non-responsive

Front 58

ACTH Stimulation Test
-Stress-induced hyperplasia expected reults

Back 58

-exaggerated response in 1 out of 7

Front 59

ACTH Stimulation Test
-expected results with Primary hypoadrenocorticism, iatrogenic hyperadrenocorticism, iatrogenic hypoadrenocorticism

Back 59

-No response