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59 Cards in this Set
- Front
- Back
Describe the normal activity of the Adrenocortical system in releasing cortisol
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-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 |
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Describe the normal activity of the Adrenocortical system in releasing Aldosterone
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-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 |
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CRH
-define |
-corticotropin-releasing hormone
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ACTH
-define |
-Adrenocorticotropic hormone
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Aldosterone release
-promoters -inhibitors |
Promoters:
-Angiotensin II -Hyperkalemia -Hyponatremia Inhibitors: -Atrial natriuretic peptide |
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Main Adrenocortical hormones
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-Cortisol
-Aldosterone -Progesterone -Cholesterol |
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Hyperadrenocorticism
-aka |
-Cushings
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Hyperadrenocorticism
-types |
-pituitary dependent hyperadrenocorticism
-functional adrenocortical neoplasm -stress-induced adrenocortical hyperplasia |
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Hypoadrenocorticism
-aka |
-Addisons
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Iatrogenic
-define |
-related to the actions of a medical person
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Hypercorticolemia
-caused by |
Spontaneous conditions:
-pituitary dependent hyperadrenocorticism -functional adrenocortical neoplasm -stress-induced adrenocortical hyperplasia Iatrogenic conditions: -Exogenous ACTH administration |
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Pituitary-dependent hyperadrenocorticism (PDH)
-pathogenesis |
-Pituitary neoplasm
--ACTH production ---adrenocortical hyperplasia ----inc. Cortisol production |
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Function Adrenocortical Neoplasia (FAN) causing hyperadrenocorticism
-pathogenesis |
-Neoplastic adrenocortical cells
--inc. cortisol production |
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Stress-induced Hypercortisolemia
-pathogenesis |
-stress stimulated hypothalamus to release CRH
--CRH stimulates Pituitary release of ACTH ---Adrenocortical hyperplasia ----Inc. cortisol production |
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Primary hypoadrenocorticism
-due to |
-bilateral adrenocortical hypoplasia
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Primary hypoadrenocorticism results in
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-dec. cortisol production
-dec aldosterone production --> electrolyte changes (loss of Na+ and Cl- & retention of K+ and H+) |
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Iatrogenic hyperadrenocorticism
-drugs used |
Steroids
-prednisone -prednisolone |
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Iatrogenic hyperadrenocorticism
-main effects |
-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) |
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Iatrogenic hypoadrenocorticism
-due to |
-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 |
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Drug that can result in iatrogenic hypoadrenocorticism
-purpose for use |
-Mitotane
-adrenolytic agent used to selectively destroy adrenocortical cells when an adrenal neoplasm is present |
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Why is the Urinary Cort:Crt ratio of use?
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-amount of creatinine excreted per day is constant, so any increase in the ratio represents and increase in cortisol excretion
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What is important to know about the units used in the urinary Cort:Crt ratio?
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-cortisol measured in nmol/L
-creatinine measured in mmol/L so ratio of "20" means 0.000020 |
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Urinary Cort:Crt ratio
-if WRI -if high |
-WRI: does not have hyperadrenocorticism
-High: may or may not have hyperadrenocorticism |
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Inc. urinary Cort:Crt ratio in a PU/PD with suspect cushings
-interpretation |
-if WRI: probably not cushnoid
-if inc.: unknown |
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Hyperadrenal diseases to expect
-high [ACTH] -low [ACTH] |
High:
-PDH -Primary hypoadrenocorticism Low: -FAN |
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Why does measurement of ACTH have limited use in dogs and cats?
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-expensive
-unstable |
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[ACTH] measurement can be used to differentiate..
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-PDH from FAN
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If an dog is cushnoid with dec. [ACTH] then....
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-FAN
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If and dog is cushnoid with inc. [ACTH] then...
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-PDH
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If dog is Addisonian with dec. [ACTH] then...
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-secondary hypoadrenocorticism (rare)
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If dog is Addisonian with no dec. [ACTH] then...
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-Primary hypoadrenocorticism
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If cat is Cushnoid with dec. [ACTH] then...
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-FAN
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If cat is cushnoid with no dec. [ACTH] then ...
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-PDH
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If cat is Addisonian with inc. [ACTH] then...
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-primary hypoadrenocorticism
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LDDST
-define |
-Low-dose dexamethasone suppression test
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LDDST
-procedure |
-take a pre-dexamethason sample for [cortisol]
-give dexamethasone IV -at 4 & 8 hrs later take sample for [cortisol] |
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LDDST
-expected results for a healthy animals -why |
-dec. cortisol (<1.4 ug/dL)
-all suppress -suppression of CRH and ACTH |
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LDDST
-expected results for dogs with PDH |
-most with no suppression in [cortisol] (72%)
-some become suppressed then escape |
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LDDST
-expected results for dogs with FAN |
-no suppression in [cortisol] (100%)
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LDDST
-expected results for dogs with nonadrenal (stress induced) hypercortisolemia |
-most suppress
-many do not suppress |
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HDDST
-define |
-high-dose dexamethasone suppression test
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HDDST
-expected results for healthy dogs |
-suppression
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HDDST
-expected results for dogs with PDH |
-most suppression
-some don't suppress |
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HDDST
-expected results for FAN |
-no suppression
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HDDST
-expected results for non-adrenal (stress) disorders |
-expect suppression
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Conditions that may show suppression by LDDST
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-healthy
-Non-adrenal (stress) |
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Conditions that may show suppression by HDDST
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-Healthy
-PDH -Non-adrenal (stress) |
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Cortisol half-life
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- <2 hrs
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Differentials for non-suppressed LDDST and non-suppressed HDDST
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-FAN
-PDH |
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Differentials for non-suppressed LDDST & suppressed HDDST
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-PDH
-Non-adrenal disease -NOT FAN |
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Differentials for an LDDST that is suppressed and escapes, and a suppressed HDDST
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-PHD
-Non-adrenal disease -NOT FAN |
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Differentials for suppressed LDDST and suppressed HDDST
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-Healthy
-Non-adrenal NOT FAN Probably not PDH |
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Types of abnormal adrenal glands and their responses to exogenous ACTH
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-hyperplastic glands: exaggerated response
-neoplastic glands: some normal, some exaggerated, some with no response -hypoplastic glands: no response |
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ACTH Stimulation test
-procedure |
-take pre-ACTH sample to check [cortisol]
-give ACTH -take post-ACTH sample (1-2 hrs) to check [cortisol] |
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ACTH Stimulation test
-healthy dog expected results |
-inc. cortisol production ( < 17 ug/dL)
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ACTH Stimulation test
-PDH expected results |
-exaggerated response
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ACTH Stimulation test
-FAN expected results |
-1/2 responsive
-1/2 non-responsive |
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ACTH Stimulation Test
-Stress-induced hyperplasia expected reults |
-exaggerated response in 1 out of 7
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ACTH Stimulation Test
-expected results with Primary hypoadrenocorticism, iatrogenic hyperadrenocorticism, iatrogenic hypoadrenocorticism |
-No response
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