Exam 4 - Hyperadrenocorticism Flashcards
T/F: for hypercortisolism, in regards to chronic exposure to glucocorticoids, exogenous exposure includes topical medications
true
in a normal dog, how is cortisol release controlled by the HPA axis?
in a normal dog, cortisol is only released when ordered by ACTH
ACTH release is determined by CRH from the hypothalamus
cortisol exerts a negative feedback on CRH (powerful) & ACTH (modest) release
what part of the adrenal gland releases cortisol? what do the other parts of the adrenal gland produce?
zona fasciculata - produces cortisol & corticosterone
adrenal cortex
1. zona glomerulosa - produces aldosterone (superficial layer - mineralocorticoids)
2. zona fasciculata - cortisol (middle)
3. zona reticularis - androgens/sex hormones (deep)
adrenal medulla - catecholamines (epinephrine & norepinephrine)
what are the 2 forms of spontaneous hypercortisolism? which is more common?
- pituitary-dependent hypercortisolism, MORE COMMON
- functional adrenal cortical tumor
what dogs are commonly affected by PDH?
mini poodles, dachshunds, beagles, bostons - middle aged to older dogs
what is the pathogenesis of PDH?
underlying cause is a secretion of ACTH by anterior pituitary tumor that is usually an adenoma & <1 cm in diameter
chronic adrenal stimulation from excessive ACTH release results in bilateral adrenal enlargement
what is the most common form of hypercortisolism?
PDH - >85% of cases, especially in small dogs
what is the pathogenesis of adrenal tumor hypercortisolism?
can either be malignant or benign tumor - 50/50 shot (malignant tumors are very aggressive)
endogenous ACTH release is very low due to negative feedback from the excessive cortisol release from the tumor
the contralateral adrenal tumor becomes atrophied
what dogs are affected by functional adrenal cortical tumors causing hypercortisolism?
<15% of cases
dogs > 20kgs - GSD predisposed
what is the most common clinical sign seen in animals with hypercortisolism? why do they have it?
PU/PD!
polyuria - due to compromised secretion of ADH & the impairment of the action of ADH on the collecting ducts
T/F: hypercortisolism is the most common cause of hyposthenuria
true
does a urine specific gravity > 1.030 make hypercortisolism likely or unlikely? why?
unlikely - there is compromised secretion of ADH & impairment of ADH/s actions on the collect ducts!
urine is often < 1.015 or hyposthenuric
why do we see increased thirst & hunger in animals with hypercortisolism?
increased thirst - secondary to the increased obligatory water loss in the urine
increased hunger - chronic glucocorticoid release stimulates the release of ghrelin from the stomach (hunger hormone) & ghrelin antagonizes insulin production from the beta cells of the endocrine pancreas
insulin antagonism results in compromised feelings of satiety & chronic hunger
what respiratory signs are seen in animals with hypercortisolism?
panting is common due to changes in pulmonary perfusion
pickwickian syndrome due to fat deposits in the thoracic cavity
what dermatological signs are seen in animals with hypercortisolism?
truncal alopecia, thinning of the dermis, secondary pyoderma, skin fragility in cats, comedomes
calcinosis cutis in dogs - classic for hypercortisolism but uncommon
why do we see abdominal distension in animals with hypercortisolism?
increased intra-abdominal fat, hepatomegaly, loss of abdominal muscle strength
T/F: in dogs with hypercortisolism, the lowest point of the abdomen is often the liver
true
what reproductive signs are seen in animals with hypercortisolism?
anestrus in females
testicular atrophy in males
what musculoskeletal changes are seen in animals with hypercortisolism?
loss of abdominal muscles causes pot belly appearance
‘barrel on sticks’
stretching of the carpal & tarsal ligaments
what consequences are seen as a result of hypercortisolism?
chronic infections - pyoderma/UTIs
poor healing post-injury or surgery
hypertension, proteinuria, pulmonary thromboembolism, decrepitude, & poor quality of life
what is seen upon physical exam that lends suspicion to a diagnosis of hypercortisolism?
old/decrepit animal
skin changes
abdominal distension/pot belly look
bruising
poor musculature & hyperextension of the ligaments especially in the carpus
what are the 3 reasons in which you may pursue a workup for hypercortisolism?
- owner has a complaint that suggests hypercortisolism - urinating in the house, stealing food, etc
- clinical impression - exam room diagnosis, patient is overtly cushingoid
- medical issues suggest hypercortisolism - recurrent infections (skin, uti), hypertension, proteinuria, thromboembolism, & uncontrolled diabetes mellitus with insulin resistance
what is the most consistent finding on biochemistry of dogs with hypercortisolism?
elevated ALP - almost 100%
what changes are often seen on CBC in animals with hypercortisolism?
hematocrit often increased
WBC usually elevated - classic stress leukogram
increased platelets