Management of Hyperadrenocorticism Flashcards
Describe how the low dose dex test is performed.
A dose of dexamethasone is given IV, which should have a negative feedback response on CRH release from hypothalamus and ACTH release from the pituitary
-should have a decreased cortisol to a value below 1 at the 4 and 8 hours in a normal animal (also known as complete suppression)
What are the options for differentiating a pituitary and adrenal based cushings disease after performing a low dose dex test?
-abdominal ultrasound
-endogenous ACTH test
If you got a complete suppression result from a low dose dex test in a dog you suspected cushings in, what does this tell you?
The dog does not have cushings
-pursue another differential
-this test has a very high sensitivity and specificity
What is the significance of being above 50% value of resting cortisol at both the 4 and the 8 hour mark?
Indicates lack of suppression
-has very high sensitivity and specificity for diagnosing cushing’s disease
*does not distinguish between the pituitary and adrenal form of the disease
What on a low dose dex test indicates that the cushings disease is likely pituitary dependent?
The cortisol level dropping below 50% of the resting at EITHER the 4 or 8 hour mark or both
-but not below the reference range of 1
AKA partial suppression
What is the most readily available drug that we have in order to treat pituitary dependent disease?
Trilostane
-this is the first line and the gold standard
What is the main concern with giving mitotaine?
It can cause necrosis of the adrenal cortex and send animals into Addisonian state
-then have to manage the Addison’s (there could be worse things)
What are the recommendations for giving trilostane?
-start at 1-2 mg/kg BID (lower than dose label)
-give with food to maximize intestinal absorption
-can cause mild lethargy or hyporexia following commencement (often resolves after several days)
-should give the brand name product and not compounded products
What is the recommended test to perform in order to determine whether the current dose of the medication is effective?
ACTH stim test
-monitoring test of choice
-assesses the ability of the adrenal gland to produce cortisol
What is the goal for trilostane therapy in terms of the ACTH stim results?
Post ACTH cortisol of 1.5-5.5 WITH control of clinical signs
After you start a dog on Trilostane, when should you next see the animal back and what should you do?
See back in 10-14 days, perform ACTH stim
-during this visit, you are just checking to be sure cortisol level is not too low (if its too low, decrease or stop the dose)
-DO NOT INCREASE DOSE during this visit even if post ACTH cortisol is >5.5. Can take up to 30 days to see full result
What should you do at the 1 month check after starting Trilostane?
Another ACTH stim test
-if the post-ACTH cortisol is >5.5 and clinical signs are still present, then the dose can be increased by 25%
-If post-ACTH cortisol is >5.5 but there are no clinical signs present, do not increase the dose
If you increase the dose at a visit, when should the next stim test be performed?
2 weeks later
What should you do if you run an ACTH stim and the post ACTH cortisol is below 1.5? If below 0.7?
<1.5: Stop trilostane for 5-7 days then restart at a 35-50% dose reduction
<0.7: stop trilostane and don’t restart until signs of hyperadrenocorticism return and adrenal function returns to normal (ACTH stim)
What are some ways to save money with a cushings diagnosis?
-Treat strictly based on clinical signs
-dont worry about the pre-ACTH stim test
-dont have to treat it, but there may be life threatening complications (hypercoagulable state)
