Hyperadrenocorticism (Cushings)

Question 1

Which portion of the adrenal gland cortex secretes cortisol?
A. zona glomerulosa
B. zona fasiculata
C. zona reticularis

Answer 1

B. zona fasiculata

Question 2

Which portion of the adrenal gland cortex secretes aldosterone?
A. zona glomerulosa
B. zona fasiculata
C. zona reticularis

Answer 2

A. zona glomerulosa

Question 3

Which portion of the adrenal gland cortex secretes aldosterone?
A. zona glomerulosa
B. zona fasiculata
C. zona reticularis

Answer 3

C. zona reticularis

Question 4

What does the medulla of the adrenal gland secrete?

Answer 4

catecholamines (norephi and epi)

Question 5

Which is the more common type of hyperadrenocorticism?
A. pituitary dependent
B. adrenal dependent

Answer 5

A. pituitary dependent

PDH is caused by a benign (adenoma) tumor or hyperplasia of the adrenal gland that leads to excess secretion of ACTH, which results in excess cortisol secretion.

Question 6

What are the MOST common clinical signs associated with hyperadrenocorticism?

Answer 6

1. PU + compensatory PD
2. truncal alopecia (non-pruritic), thin skin, calcinosis cutis, comedones
3. polyphagia
4. abdominal distention
5. panting
6. muscle wasting/ weakness

Question 7

What would you expect to see on a CBC in a dog with hyperadrenocorticism?

Answer 7

RBCs - normal

WBCs- stress leukogram (neutrophilia, lymphopenia, eosinopenia)

platelets - thrombocytopenia

Question 8

What would you expect the liver enzymes of a patient with hyperadrenocorticism to look like?

Answer 8

both elevated
ALP > ALT

Question 9

What might a urinalysis of a patient with hyperadrenocorticism show?

Answer 9

dilute urine (SG <1020)
proteinuria
UTI

Question 10

How would you interpret a UC:CR > reference range value?

Answer 10

UC:CR is a screening test for hyperadrenocorticism

A UC:CR value that is ABOVE the ref range value indicates POSSIBLE HAC. It does not confirm any diagnosis.

A UC:CR value below the reference range indicates this patient does not have HAC.

Question 11

What would you expect the results of a low dose dexamethasone suppression test to be in a patient without HAC (normal patient)?

Answer 11

0-hour (above ref range)
4-hour (below ref range)
8-hour (below ref range)

you are seeing complete suppression of CRH and ACTH, and thus lowered cortisol levels.

Question 12

What low dose dexamethasone suppression test result would indicate that a patient has hyperadrenocorticism?

Answer 12

0-hour (above ref range)
4-hour (above ref range AND above 50% of the 0-hr cortisol)
8-hour (above ref range AND above above 50% of the 0-hr cortisol)

You are seeing a LACK of suppression indicating there is excess ACTH and cortisol production.

Question 13

What low dose dexamethasone suppression test results would indicate that pituitary-dependent hyperadrenocorticism is likely?

Answer 13

0-hour (above ref range)
4-hour (above ref range +/- less than 50% of the 0-hr value but still above the ref range)
8-hour (above ref range +/- less than 50% of the 0-hr value but still above the ref range)

Here, you are seeing partial suppression. It looks like complete suppression except the 4 and 8-hour values are still above the reference range. This occurs in 60% of PDH cases.

Question 14

What is the treatment for hyperadrenocorticism?

Answer 14

trilostane (vetoryl)
starting at 1-2 mg/kg BID

Question 15

What are the 3 goals of treating patients with HAC with trilostane?

Answer 15

1. decrease PU/PD
2. decrease the ravenous appetite
3. hair regrowth

the first 2 occur within days/weeks, hair regrowth takes months.

Question 16

Which test is used for monitoring a patient on trilostane and when should it be performed?

Answer 16

ACTH stimulation test

1. Perform first ACTH stim 2 weeks after diagnosis (DO NOT DO ANY DOSE ADJUSTMENTS. THIS IS ONLY TO ENSURE YOU ARE NOT OVERSUPPRESSING AND CAUSING ADDISIONS)
2. perform 2nd ACTH stim 30 days after diagnosis (this time you can change dose if needed)
3. perform an ACTH stim 2 weeks after ANY dose change

Question 17

You perform an ACTH stimulation test on a dog that is currently receiving trilostane after being diagnosed with cushings 2 weeks ago. The results show that the post-ACTH cortisol is 8.9. What is your plan?

Answer 17

Do not increase the dose.
This first ACTH stim test is just to make sure you are not oversuppressing the patient and causing addisons.
You can make dose adjustments if needed on the next ACTH stim test (30 days after initial diagnosis)

Question 18

T/F: a low-dose dexamethasone suppression test is quicker than an ACTH stimulation test

Answer 18

false – LDDST takes 8 hours, ACTH stim takes 1 hour.

Question 19

What diagnostic is best for determining whether a case of hyperadrenocorticism is pituitary dependent or adrenal dependent and what specific finding tells you its one or the other?

Answer 19

abdominal ultrasound
in adrenal-dependent HAC, there will be a mass on the affected gland, but the contralateral gland is smaller.

in pituitary dependent, there is bilaterally symmetric enlargement of the adrenals.

Question 20

If an owner did not want to pursue trilostane for adrenal-dependent HAC, what is there option?

Answer 20

adrenalectomy

this is curative, but there are risks.

Question 21

T/F: you can test for cushings even if the patient does not have clinical signs.

Answer 21

false – do not test unless they have clinical signs.