Hyperadrenalcortism Flashcards
What are the presenting signs seen in dogs with HAC (hyperadrenocorticism)
POLYPHAGIA, PU/PD, abdominal enlargement (pot-bellied), muscle weakness, SKIN (bilateral truncal alopecia, CALCINOSIS CUTIS, THIN SKIN, bruising, comedones, hyperpigmentation) heat intolerance, panting, lethargy, obesity, reproductive (anestrus, testicular atrophy), neuro (facial paralysis, pseudomyotonia)
What are the different types of HAC
Pituitary Dependent HAC
Adrenal dependent HAC
Iatrogenic HAC
What is the test of choice for HAC
Low Dose Dexamethasone Suppression Test (LDDS)
What are all the tests Available for HAC and some strength/weaknesses for each
Urine Corrisol:Creatinine Ratio - good screening test that you can use when the patient is not sick but has some clinical signs
AtCH stimulates test- Gold standard test for iatrogenic HAC
LDDS - screening test of choice for HAC. Patients MUST have clinical signs of HAC to interpret results, it could potentially help with identifying where the neoplasia is
HDDS - similar to LDDS
How do you treat a case of HAC
Surgery (referral for both removing an adrenal or hypophysectomy)
Medical management - 1. Trilostane - blocks the synthesis of adrenal and gonadal steroid hormone (must continue to monitor as adrenal will continue to enlarge.) 2. Mitotane - adrenocorticolytic (destroys adrenal cortex) monitor as you can over treat (cause hypoadrenocortism)
What are some hormones secreted from the Pituitary gland
Posterior- ADH and oxytocin
Anterior - ACTH, TSH, growth hormone, and sex hormones
What are the zones of the adrenal gland and what does each get stimulated by to produce what
Zona Glomerulosa - stim by Ang II and K, produces mineral corticosteroids
Zona Fasiculata and Reticularis - stim by ACTH to produce glucocorticoids
Medulla- sympathetic nervous system to produce catecholamines
What is Pituitary Dependent HAC
Pituitary tumor making ATCH bursts at a chronic length which will cause an excess of systemic cortisol and adrenocortical hyperplasia.
Seen in 80-85% cases, normally a pituitary adenoma, most are small some are big and cause compression on cns
What is Adrenal Dependent HAC?
Excessive cortisol secretion caused by an adenoma/carcinoma of the adrenal gland. This is typically unilateral where the unaffected gland will atrophy and there will be suppression of the ATCH negative feedback loop (pituitary independent)
What is iatrogenic HAC
A systemic increase of cortisol due to steroids that will suppress ATCH. Hence you will get a bilateral adrenocortical atrophy.
What is the human disease name that represents canine HAC
Cushings
What are some complications associated with HAC
Hypertension, proteinuria, PTE/ATE, UTI, uroliths, CHF, pancreatitis, DM, joint laxity/ligament tears
HAC clinpath findings
CBC - stress leukogram, thrombocytosis
Biochem - ELEVATED ALKP, ALT, CHOLESTEROL, TRIGLYCERIDES mild elevated BA, BG, sodium and decrease in potassium
UA - often hyposthenuria, ELEVATED UPC, see UTI
What would a normal vs elevated urine cortisol:creatinine ratio indicate
Normal - most likely doesn’t have HAC
Elevated - might have HAC must do further testing
How would you interpret test results of an ATCH stim test
ACTH stim test - take baseline cortisol levels, then inject with synthetic ATCH then after 60-90 mins analyze the results
In normal patients their cortisol levels should rise
In HAC they should have a super high cortisol response
In iatrogenic HAC (or Addisons) they will have a flatline
How would you interpret a low dose dexamthasone suppression test
LDDS - attain baseline cortisol, inject dexamethasone, and measure 4 and 8 hours post injection
-Normal patients their cortisol should be suppressed
-In pituitary dependent hyper cortisol you will see no suppression at the 8hr but suppression at the 4 hour
-If you have no suppression at either the 4 or 8 hour you cannot determine if it is pituitary dependent or adrenal dependent (as adrenal will never suppress but 25% of pituitary will also not suppress) so would need further testing
What are some advance imaging you can do to differentiate PDH and ADH
Ultrasound - ADH will have one enlarged adrenal gland and one atrophied. VS PDH will have bilateral hyperplasia
CT - can look at adrenal size, invasions of masses, assess for Mets
MRI - detect pituitary adenoma
What do you do when your clinical signs suggest hyperadrenocorticism but tests are inconclusive
Wait and retest
Consider ACTH stim test with sex hormone panne.
What do you do when you have minimal signs but tests suggest HAC
Hold off on treatment and monitor patient and ensure there were no false positives (like stress induced)
What is a major clinical sign in cats that they have hyperAC
Single skin tear this is due to the skin becoming super thin and fragile (can also see comedones, calcanious cutis)
If cats are presenting with diabetes and hypertension what should you do
Look for something else other than the diabetes going on. Cats with hyperAC will present as diabetic
