Term
| Causes of Hypercortisolism |
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Definition
pituitary dependent (most common) = micro/macroadenoma of pars distalis causing bilateral adrenal hyperplasia
Adrenal Tumor
Iatrogenic |
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Term
| Signalment of Hypercortisolism |
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Definition
middle aged to older dogs and cats
Poodle, Boston Terrier, Boxer, Daschund
mostly female cats and dogs |
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Term
| Clinical Signs of Hypercortisolism |
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Definition
PU/PU in most patients due to ADH antagonism
concurrent diabetes mellitus
decreased renal tubular water permeability
decreased vasopressin secretion
UTI associated with steroids
dilute urine predisposes it to UTI or having glucosuria
Bilaterally symmetrical alopecia
Very thin skin (skin tear, decubital ulcers)
Hyperpigmentation
Comedones
Muscle atrophy due to direct effect of glucocorticoids
Potbelly due to abdominal muscle weakness and redistribution of fat and hepatomegaly
myotonia is uncommon due to non-inflammatory degenerative myelopathy
Panting is common
Dyspnea due to pulmonary embolism
Insulin resistance and diabetes
Seizures, blindness, circling due to macroadenoma |
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Term
| Diagnosing Hypercortisolism |
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Definition
history and physical exam are the most important
urinalysis shows isosthenuria, proteinuria
CBC shows lymphocytopenia, monocytosis
elevated ALP, ALT, hyperglycemia, hypercholesterolemia, hypernatremia, hypokalemia
mild elevations in blood pressure
hepatomegaly, pulmonary metastasis
ultrasound shows adrenal hyperplasia, atrophy, or tumor |
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Term
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Definition
establishes a diagnosis of hypercortisolism
low dose dex suppression, ACTH stim test |
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Term
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Definition
to differentiate pituitary from adrenal tumor
high dose dex suppression, endogenous ACTH |
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Term
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Definition
cortisol is measured before and 60-90 minutes after synthetic ACTH is given IM
use normal value specific for your lab
highly sensitive
fairly specific if clinical signs warrant |
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Term
| Low Dose Dexamethasone Suppression Test |
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Definition
| cortisol should fall below 40nM and remain for 8 hours |
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Term
| High Dose Dexamethasone Suppression Test |
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Definition
failure to suppress indicates 50% chance of an adrenal tumor
failure to suppress may indicate macroadenoma |
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Term
| Dexamethasone Suppression Test |
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Definition
Dexamethasone has 8-10 times the potency of cortisol
Dexamethasone shuts of CRH and ACTH to cause cortisol to drop because of negative feedback system |
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Term
| Urine Cortisol:Creatinine |
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Definition
reflects high serum cortisol over time
first morning urine should be used
measure urine cortisol and creatinine in mmol/L
ratio of >35 is suggestive of Cushing's
high negative predictive value
very non-specific |
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Term
| Plasma ACTH Concentation Test |
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Definition
elevated in pituitary-dependent Cushings
decreased in adrenal tumors |
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Term
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Definition
adrenocorticolytic
dangerous because it is really effective
side effects due to steroid withdrawal or drug effects
have induction phase to blast the disease into remission
then do an ACTH stim test and want a low-normal test
then you go to maintenance dose
relapses are common
medical adrenalectomy can be done and then treat for Addison's |
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Term
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Definition
steroidogenesis inhibitors
side effects are less common because it is less effective |
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Term
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Definition
| for adrenal tumors for cats |
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