Pathophysiology of the Adrenal Glands Flashcards
what are the glucocorticoid actions?
carbohydrate metabolism
protein metabolism
fat metabolism
effects on inflammation
effects on blood
other effects
what do glucocorticoids do with carbohydrate metabolism?
stimulate hepatic gluconeogenesis
decrease rate of peripheral cellular glucose utilization
what do glucocorticoids do with protein metabolism?
reduce protein stores: decrease synthesis and catabolic effect
what are the anti-inflammatory effects of glucocorticoids?
stabilizes lysosomal enzymes
decreases capillary permeability
decreases phagocytosis by white blood cells
suppresses T lymphocytes
anti-pyretic
what is the adrenal cortex divided into?
zona glomerulosa
zona fasciculata
zona reticularis
what is the etiology of the majority of dogs with Cushing’s disease?
pituitary-dependent
micro or macroadenoma of the anterior pituitary
what percentage of dogs with Cushing’s have an adrenal tumor?
15-20%
which dogs are more likely to have adrenal tumors?
larger dogs
65% female
what breed is predisposed to both pituitary-dependent Cushing’s and adrenal tumor?
poodles
what are the clinical signs of Cushing’s disease?
PU/PD
polyphagia
abdominal enlargement
muscle weakness
lethargy
dermatologic signs
what is calcinosis cutis?
dermatologic sign with Cushing’s: mineralized
what are the respiratory signs associated with Cushing’s disease?
increased panting: obesity, muscle weakness, dyspnea due to pulmonary thromboembolism, pneumonia (predisposed)
what is steroid hepatopathy?
deposition of glycogen in hepatocytes
results in hepatomegaly
vacuolar hepatopathy
what are the neurologic signs associated with Cushing’s disease?
mental dullness
disorientation
anorexia
restlessness
aimless pacing
ataxia
what are the CBC findings with Cushing’s disease?
leukocytosis
mild erythrocytosis
thrombocytosis
what is increased in greater than 85% of dogs with Cushing’s on their chemistry profile?
alkaline phosphatase activity
what do most cats with Cushing’s disease have?
diabetes mellitus
where does POMC and ACTH come from?
pars intermedia
what is the epidemiology of equine hyperadrenocorticism?
older horses and ponies
breed predisposition maybe: ponies, morgans
what are the main clinical signs of equine hyperadrenocorticism?
hisutism/hypertrichosis
hyperhidrosis
muscle loss
abnormal fat distribution
chronic laminitis
how common is hyperadrenocorticism in ferrets?
very common endocrine disorder
what do ferrets produce in excess in hyperadrenocorticism?
estradiol-17beta: most common
17-hydroxyprogesterone
androstenedione
dehydroepiandrosterone sulfate
what is thought to be the etiology of hyperadrenocorticism in ferrets?
early spaying a neutering
hereditary
unnatural light cycles
what species does not get polydipsia/polyuria with hyperadrenocorticism?
ferrets
what are the clinical signs of hyperadrenocorticism in ferrets?
progressive alopecia
generalized pruritus
thin skin
spayed females: enlarged vulva
neutered males: aggression, prostatic hyperplasia, dysuria
anemia, thrombocytopenia
who is hyperaldosteronism seen in?
occasionally in cats
rarely in dogs
what is hyperaldosteronism due to?
aldosterone-secreting adrenal tumor
what are the clinical consequences of hyperaldosteronism?
serum chemistry abnormalities
hypokalemic polymyopathy
hypertension
what are the clinical signs of hyperaldosteronism?
weakness
cervical ventrofelxion
blindness/retinal detachment
what does hypoadrenocorticism typically result from?
destruction of all three layers of the adrenal cortex
what is the etiology of hypoadrenocorticism?
idiopathic atrophy
immune-mediated destruction
iatrogenic
generalized infections
metastatic neoplasia
trauma
infarction
which breeds have familial hypoadrenocorticism?
standard poodles
leonbergers
bearded collies
nova scotia duck tolling retrievers
portuguese water dogs
how common is hypoadrenocorticism in cats?
uncommon
what are the clinical signs of hypoadrenocorticism?
can be episodic illness
glucocorticoid vs mineralocorticoid deficiency
gastrointestinal signs
acute collapse and shock
what are the cbc findings with hypoadrenocorticism?
mild anemia
leukogram
lack of stress leukogram on a sick patient
what are the chemistry findings with hypoadrenocorticism?
hyponatremia and hyperkalemia
azotemia
hypoglycemia
hypercalcemia
hypoalbuminemia
what are the effects of norepinephrine?
more restricted
generalized vasoconstriction
pupil dilation
decreased gastrointestinal function
what is the hallmark physiologic abnormality of pheochromocytoma?
hypertension
what are the clinical signs of pheochromocytoma?
generalized weakness, collapse
panting, tachypnea
lethargy, anorexia
tachycardia
polyuria/polydipsia
profuse sweating/panting
anxiety
flushing
horses: muscle fasciculations, abdominal pain
what do clinical signs and physical examination findings come from with pheochromocytoma?
space-occupying nature of tumor
metastatic lesions
secretion of catecholamines
spontaneous hemorrhage
what is pheochromocytoma?
tumorof adrenal medulla resulting in excess and episodic production of epinephrine and norepinephrine
how are glucocorticoids metabolized?
unbound: renal
primarily hepatic
what proteins bind glucocorticoids in the blood?
cortisol-binding globulin
albumin
how do glucocorticoids effect fat metabolism?
promote mobilization of fatty acids
enhance fatty acid oxidation
decrease glucose transport into cells
increase insulin secretion
how do glucocorticoids cause hypertension?
increased levels of renin substrate
what are the mechanisms of cortisol excess in the dog?
corticotroph adenoma, adenohypophysis
adrenal cortical adenoma or carcinoma
iatrogenic
ectopic ACTH secretion
what is the etiology of canine hyperadrenocorticism that is pituitary-dependent (PDH)?
micro or macroadenoma of the anterior pituitary
85-90% of cases
how common are adrenal tumors that cause canine hyperadrenocorticism?
15-20%
50% benign or malignant
what are the etiologies of dogs with hyperadrenocorticism that are not pituitary dependent?
adrenal tumor
iatrogenic
sex hormone related
who commonly gets canine hyperadrenocorticism due to an adrenal tumor?
median 11.3 years
65% female
more common in larger dogs
what dog breeds are predisposed to pituitary dependent hyperadrenocorticism?
poodle
dachshund
terriers
beagle
german shepherd
boxer
what dog breeds are predisposed to an adrenal tumor causing hyperadrenocorticism?
poodle
german shepherd
dachshund
labrador retriever
terriers
what does steroid hepatopathy result in?
hepatomegaly
what does SMILED stand for?
for hyperadrenocorticism
Segs and Monos Increase
Lymphs and Eos Decrease
what contributes to the hypercoagulable state in canine hyperadrenocorticism?
thrombocytosis
decreased antithrombin
increased fibrinogen
hypertension
how many cats with feline hyperadrenocorticism have concurrent diabetes mellitus?
80%
is it more common for cats to have hyperadrenocorticism due to pituitary dependent hyperadrenocorticism or an adrenal tumor?
pituitary dependent 80%
what is the pathophysiology of pituitary pars intermedia dysfunction in terms of hormones?
POMC and ACTH come from pars intermedia
what are the clinical signs of pituitary pars intermedia dysfunction?
hirsutism/hypertrichosis
hyperhidrosis
weight and muscle loss
normal to increased appetite
abnormal fat distribution
docile behavior
chronic laminitis
polydipsia/polyuria
chronic infections
delayed wound healing
what is the pathophysiology of hyperadrenocorticism in ferrets?
excess production of sex steroids by the adrenal
half adrenocortical hyperplasia
26% adrenocortical carcinoma
16% adrenocortical adenoma
why is early spaying and neutering thought to contribute to hyperadrenocorticism in ferrets?
remove negative feedback of estrogen and testosterone on production of gonadotropin-releasing hormone
stimulates follicle stimulating hormone and luteinizing hormone receptors on adrenal gland
do ferrets get polydipsia and polyuria with hyperadrenocorticism?
no
what are the causes of hyperaldosteronism in cats?
adrenal adenoma
carcinoma: unilateral
what are the serum chemistry abnormalities associated with hyperaldosteronism?
hypernatremia
hypokalemia
what is hypoadrenocorticism from loss of?
mineralocorticoids and glucocorticoids
what does hyponatremia in hypoadrenocorticism result in?
volume depletion
hypotension
what does hyperkalemia in hypoadrenocorticism result in?
decreased muscle cell excitability
increased refractory period
slowed conduction
how common is hypoadrenocorticism in cats?
rare
what are the gastrointestinal signs associated with hypoadrenocorticism?
vomiting
diarrhea
anorexia
weight loss
what is found of physical examination with hypoadrenocorticism?
depression, lethargy
generalized muscle weakness
bradycardia, weak pulse
dehydration
hypothermia
hyperpigmentation
peripheral lymphadenopathy
what is on the leukogram with a CBC of a hypoadrenocorticism patient?
eosinophilia
lymphocytosis
what is the mild anemia like with hypoadrenocorticism?
normocytic, normochromic
nonregenerative
what ratio of Na:K is consistent with hypoadrenocorticism?
<22:1
what is an atypical presentation of hypoadrenocorticism?
clinical signs of glucocorticoid deficiency, but normal serum electrolytes
impaired secretion of ACTH
adrenocortical deficiency: zona fasciculata more far gone than zona glomerulosa
what are the effects of epinephrine?
diverse activity
selective vasoconstriction
cardiac effects
metabolic effects
bronchodilation
who is pheochromocytoma reported in?
cattle and dogs
less frequent in cats and horses
