Endocrinology - Cushings 2 Flashcards
How do you differentiate AT from PDH?
Diagnostic imaging, LDDST, HDDST, and endogenous ACTH concentrations
If you have a pituitary microadenoma, what does it secrete and how will the adrenal glands look?
It causes bilateral adrenomegaly due to excessive ACTH
Why is an ultrasound only a differentiating test for PDH?
Because adrenals with PDH can be a normal size
What do functional adrenal tumors do?
They secrete cortisol independent of pituitary control
Why is CT/MRI not a reliable differentiating test between FAT and PDH?
It can find a macroadenoma, but cannot differentiate all microadenomas from normal so it is not a reliable differentiating test
How do dogs react to a HDDST if they have a FAT?
There is not cortisol suppression
How do dogs react to a HDDST if they have PDH?
75% of dogs with PDH will suppress it at the 4 and/or 8 hour measurement
What is the disadvantage to a HDDST test?
It can never confirm the presence of a FAT
How do dogs with PDH react to endogenous ACTH?
They should have elevated ACTH levels
How do dogs with FAT react to endogenous ACTH?
They should have decreased levels due to negative feedback
How do you treat an adrenal tumor?
Surgery
What complications are associated with removal of an adrenal tumor?
Hemorrhage, thromboembolism, pancreatitis, arrhythmias, and hypoadrenocorticism
How do you medically treat PDH?
Trilostane (FDA approved) or Mitotane
How does Trilostane work?
It blocks the steriodogenesis pathway therefore inhibits cortisol production
What is the recommended dosage of Trilostane?
1 mg/kg BID PO - Low dose protocol
What adverse effects are associate with Trilostane?
Possible adrenal necrosis, vomiting, diarrhea, hyperkalemia, and Addison’s disease
Trilstane is effective in ______% of patients.
> 90% .
How quickly will PU/PD/PP improve once Trilostane is started?
within 4 weeks
How quickly will skin improve once Trilostane has been started?
within 3 months
How do you monitor effectiveness of Trilostane? When should you?
Via ACTH stimulation 4-6 hours post pill administration
After you start Trilostane, when should you do your first ACTH stimulation and why?
At 10-14 days to make sure the patient isn’t Addisonian - don’t change dose unless cortisol is too low
After the initial ACTH stim, when do you want to do the next ones?
At 30 days, then every 10-14 days until controlled, and then at 30 days, 90 days, and every 3 months thereafter
What is the goal level for ACTH stimulation in patients treating for Trilostane?
To have the pre and post ACTH cortisol concentration between 1 and 5 micrograms/dl
What is the prognosis for dogs with Trilostane therapy?
Good - median survival with PDH is almost 2 years, and with AT is around 14 months
What type of drug is Mitotane and what does it do?
It is an adrenocorticolytic that causes Zona fasciculata and reticularis necrosis
When do you want to do a recheck for a patient that has begun Mitotane therapy?
Recheck in 8 days or when appetitie decreases
What should be done at the recheck appointment in a patient that is getting Mitotane therapy?
Perform an ACTH stimulation test and repeat every 7-10 days until adequate suppression
What are the potential adverse effects associated with Mitotane therapy?
Vomiting, diarrhea, inappetance, lethargym depression, adrenocorticol necrosis, and unmask concurrent diseases such as allergies, arthritis, and UTIs
What are the non-medical options for PDH treatment?
Surgical removal of pituitary mass, radiation therapy, and a bilateral adrenalectomy
What are the major complications of not treating hyperadrenocorticism?
Hypertension, hypercoagulability, calcium oxalate urinary stones, gallbladder mucocele, and infections
What is secondary adrenocortical insufficiency also known as?
Iatrogenic Cushing’s
What is iatrogenic Cushing’s?
Glucocorticoid therapy resulting in clinical HAC due to suppression of the HPA axis
What clinical signs are associated with Iatrogenic Cushing’s?
PU/PD, polyphagia, panting, cutaneous changes, and labwork consistent with HAC
What happens when the glucocorticoids suppress the HPA axis?
They decrease CRH release from the hypothalamus, decrease ACTH release from the pituitary, and cause atrophy of the zona fasciculata
What determines the effectiveness of glucocorticoids?
Relative potency, formulation, dose, and duration
If you remove glucocorticoids in an iatrogenic Cushing’s patient, what clinical signs may they show?
Signs similar to atypical adrenocortical insufficiency - collapse, weakness, and depression
True or False: There are electrolyte disturbances in patients with iatrogenic HAC.
FALSE
How do you diagnose iatrogenic HAC?
History of glucocorticoid administration, physical findings, and ACTH stimulation test
What will an ACTH stimulation test show in patients with iatrogenic HAC?
a suppressed adrenal response similar to primary hypoadrenocorticism
How do you treat iatrogenic HAC?
Remove the source of glucocorticoid but make sure to taper the dose if a patient has been on glucocorticoids for a long period
