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84 Cards in this Set
- Front
- Back
Part of the adrenal gland that secretes catecholamines
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Medulla
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Zone of the adrenal cortex that excretes mineralocorticoids
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Zona glomerulosa
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Zone of the adrenal cortex that excretes glucocorticoids
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Zona fasiculata
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Zone of the adrenal cortes that excretes weak sex steroids
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Zona reticularis
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SIte of metabolism of corticosteroids
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Liver
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Where are metabolized corticosteroids excreted in the dog?
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Urine
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Where are metabolized corticosteroids excreted in the cat?
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Bile
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This class of substances increases liver gluconeogenesis, decrease peripheral glucose utilization, cause protein catabolism, and increase lipolysis.
Released as response to stress. Increase renal excretion of water. |
Glucocorticoids
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Released from the hypothalamus in response to stress
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Corticotropic releasing hormone
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CRH acts on pituitary gland to release...
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ACTH
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ACTH stimulates the adrenal cortex to release...
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Cortisol
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Cortisol has this effect on hypothalamus and pituitary
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Negative feedback
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Major mineralocorticoid
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Aldosterone
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True or false: Cortisol has a minor mineralocorticoid activity
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True
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This hormone maintains electrolyte balance, maintains extracellular water volume, increases renal sodium retention, increases renal potassium and H secretion, and causes a minor increase in intestinal sodium resorption.
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Aldosterone
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Aldosterone increases retention of.... and secretion of .... and ....
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Retention: Na
Secretion: K and H |
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Aldosterone has a direct effect on plasma concentration of this ion
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Potassium
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Hypotension stimulates the excretion of this hormone.
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Aldosterone
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Primary catecholamine excreted from adrenal medulla.
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Epinephrine
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Two catecholamines excreted from renal medulla.
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Epinephrine
Norepinephrine |
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This class of bioactive substances causes BV constriction, increased cardiac rate and strength, inhibits GI activity, causes mydriasis, and increases metabolic rate.
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Catecholamine
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80-85% of cases of canine hyperadrenocorticism fall under this classification:
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Pituitary dependent
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Is PDH or ADH more common?
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PDH
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Peak age on onset of hyperadrenocorticism in the dog
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7-9 years
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Is hyperadrenocorticism more common in dogs or cats?
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Dogs, by far
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Is PDH more common in males or females?
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Equal
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Is ADH more common in males or females?
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Females
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Breeds most predisposed to PDH
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Miniature poodles
Dachshunds Boston terriers Silky terriers |
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True or false: ADH occurs most frequently in small dogs.
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False. Large dogs.
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Type of hyperadrenocorticism caused by overproduction of ACTH
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Pituitary dependent
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Type of hyperadrenocorticism caused by a functional adrenal tumor
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Adrenal dependent
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Potential causes of PDH
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Functional pituitary tumor (90%)
Idiopathic excessive hypothalamic stimulation (10%) |
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Bilateral adrenal cortical hyperplasia caused by this form of hyperadrenocorticism
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PDH
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Most common type of adrenal tumor
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Adenocarcinoma
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A unilateral adrenal mass will most likely cause this form of hyperadrenocorticism
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Adrenal-dependent
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Adrenal masses tend to be either...
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Adenocarcinoma
Adenoma |
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True or false: All cases of ADH are marked by a unilateral adrenal mass.
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False. Possibly bilateral.
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If there is a unilateral adrenal mass causing ADH, how will the other adrenal gland appear?
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Atrophied b/c of negative feedback on hypothalamus and pituitary
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Type of hyparadrenocorticism that results in low ACTH
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ADH
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Type of hyparadrenocorticism that results in elevated ACTH
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PDH
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CS of hypercortisolemia
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PU/PD
Pendulous abdomen Bilaterally symmetrical alopecia Hepatomegaly Lethargy Polyphagia Muscle weakness Comedones Calcinotis cutis |
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CS of hypercortisolemia
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PU/PD
Pendulous abdomen Bilaterally symmetrical alopecia Hepatomegaly Lethargy Polyphagia Muscle weakness Comedones Calcinotis cutis |
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Most common biochemical abnormality seen with hyperadrenocorticism
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Increased serum AP
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90% of cats with hyperadrenocorticism also have...
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Diabetes mellitus
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Changes frequently seen on urinalysis with hyperadrenocorticism
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Proteinuria
Bacteriuria |
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This organ frequently becomes enlarged in hyperadrenocorticism
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Liver
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How does ultrasonaography help differentiate between ADH and PDH?
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Screens for adrenal mass and ID's gland affected
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True or false: Systemic hypertension is seen in about 25% of Cushings' patients.
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False. 60%!
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How is a definitive diagnosis of hyperadrenocorticism made?
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Typical CS
Abnormal adrenal function tests R/O other causes of PU/PD and elevated AP, etc. |
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Is urine cortisol:creatinine ratio more sensitive or specific?
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High se, low sp
(Other things can raise urine cortisol) |
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List 3 ways to differentiate PDH and ADH
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HDDS test
Endogenous ACTH Abdominal US |
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A dog with hyperadrenocorticism undergoes HDDS. What will the results be for PDH vs. ADH?
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PDH: Suppression <50% of baasal value
ADH: No suppression at 8h |
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Most reliable test for differentiating between PDH and ADH
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Endogenous ACTH
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Main treatment for PDH. How does it work?
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Trilostane, blocks cortisol production
Also mitotane, which selectively destroys adrenal cortex |
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1 year survival for PDH treated with trilostane or mitiotane
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70%
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60% of adrenal tumors causing ADH are...
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Adenocarcinomas
(Half will be inoperable at time of sx) |
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Generally, immediate post-op survival for ADH is...
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Pretty good, may approach 100%
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Primary hypoadrenocorticism results when...
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Adrenal cortices are destroyed
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Secondary hypoadrenocorticism results when...
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Lack of ACTH from pituitary gland
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Are most cases of hypoadrenocorticism primary or secondary?
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Primary
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If only glucocorticoids are deficient, is that a sign of primary or secondary hypoadrenocorticism?
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Secondary
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If both glucocorticoids and mineralocorticoids are deficient, is that a sign of primary or secondary hypoadrenocorticism?
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Primary
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Signalment for typical case of hypoadrenocorticism
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Young adult dog (4-4.5 y), usually intact female (or less commonly castrated male.)
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Is hypoadrenocorticism more common in dogs or cats?
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Dogs
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List some breeds at highest risk of hypoadrenocorticism
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Portuguese water dog
Great Dane West Highland White Terrier Standard Poodle Wheaten Terrier Rottweiler Springer Spaniel German Shorthaired Pointer Bassett Hound |
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Most common cause of primary hypoadrenocorticism
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Immune-mediated adrenal atrophy/destruction
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CS of glucocorticoid deficiency
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Weakness and lethargy
Inability to deal with stress/illness/exercise Hypoglycemia |
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Pathophysiology of mineralicorticoid deficiency
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Severe Na loss
Hypovolemia K retention Decreased secretion of H, causing acidosis Excess colonic Na and H2O loss |
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High levels of this ion may cause a negative cardiac ionotropic effect, bradycardia, no P wave, high T wave, and widened QRS.
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Potassium
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CS of hypoadrenocorticism
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Anorexia
Lethargy and depression Vomiting Weakness Wax/wane course Dehydration Diarrhea Hypothermia Shock |
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Typical biochemical abnormalities seen with hypoadrenocorticism
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Na:K under 27
High K, BUN, P Low Na High creatinine and Ca |
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Isosthenuria is more commonly associated with this adrenal dysfunction
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Hypoadrenocorticism
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Radiographic signs associated with hypoadrenocorticism
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Small heart and great vessels
Rarely transient megaesophagus |
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Small adrenal glands < 3.2 mm are consistent with...
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Hypoadrenocorticism
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Very sensitive and specific test for hypoadrenocorticism
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Basal cortisol level < 1 ug/dL
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Hypoadrenocorticism is unlikely when basal cortisol is at this level
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Over 2 ug/dL
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Definitive diagnosis of hypoadrenocorticism is made based on the results of this test...
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ACTH stimulation test
Post-stim cortisol below reference range |
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List some hematologic abnormalities seen in patients with hyperadrenocorticism.
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Eosinopenia
Lymphopenia Stress leukogram Occasionally erythrocytosis |
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When diagnosing hyperadrenocorticism, rule-outs include:
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Uncontrolled diabetes
Liver disease Renal failure |
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List three diagnositc tests for hyperadrenocorticism
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ACTH stimulation test
Low dose dexamethosone suppression test Urinary cortisol:cratinine ratio |
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Most specific test for hyperadrenocorticism (fewest false +)
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ACTH stimulation test
(High sp, low se) |
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Is LDDS test more sensitive or specific?
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High se, low sp
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Positive result on LDDS indicated by...
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Cortisol over 1 ug/dL at 8h
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Low-dose dexamethosone suppression test diagnoses this form of hyperadrenocorticism
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PDH
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