Cushingoid Complexities

Question 1

What is Cushing’s?

Answer 1

excessive production of glucocorticoids by the adrenal glands

Question 2

Three forms of hyperadrenocorticism

Answer 2

pituitary dependent (PDH)
adrenocortical neoplasia (AT)
Iatrogenic

Question 3

General description of pituitary dependent Cushings

Answer 3

80-85% of all cases
functional ACTH secreting tumor
most are <3mm
causes bilateral adrenocortical hyperplasia

Question 4

General description of iatrogenic Cushing’s

Answer 4

excessive exogenous steroids

bilateral adrenal atrophy

Question 5

General description of adrenal dependent Cushing’s

Answer 5

Adrenocortical tumors (AT)
- 50% malignant (carcinomas), 50% benign adenomas
- bilateral tumors rare but can have nonfunctioning AT w/ pheochromocytoma in opposite adrenal
- usually atrophy of contralateral glands
Macronodular hyperplasia of adrenals can occur (PDH but can be confused w/ adrenal neoplasia)

Question 6

Signalment of Cushings

Answer 6

poodles, boxers, daschunds, schnauzers, Boston terriers, G. shepherds
75% PDH cases <20kg, 50% AT >20kg
no sex predilection
rare in cats

Question 7

Clinical signs of cushings

Answer 7

PU/PD/PP, bilaterally symmetrical alopecia, thin skin, pendulous abdomen/pot belly, muscle and ligament weakness and atrophy, calcinosis cutis, hyper pigmentation, reproductive changes, respiratory signs, CNS signs

Question 8

How do you rule out iatrogenic bushings?

Answer 8

look for history of steroids including topical, oral or ophthalmic

Question 9

Lab changes you’d expect in a Cushing’s patient

Answer 9

CBC: polycythemia, stress leukogram
Chem: increased ALP, hypercholesterolemia, mild increase in ALT, mild hyperglycemia
UA: decreased specific gravity, proteinuria
Function tests: T3 and T4 decreased, fT4 and TSH normal

Question 10

T/F: most Cushing’s patients are hypertensive

Answer 10

true

Question 11

Best diagnostic test for cushings

Answer 11

Low Dose Dexamethasone Suppression Test

Question 12

Describe LDDS

Answer 12

• dexamethasone inhibits ACTH release from pituitary thereby decreasing plasma cortisol in normal dogs
• cushingoids do not suppress
• baseline cortisol, give 0.01mg/kg dexamethasone sodium phosphate IV, collect 4h and 8h post samples
• 50% suppression at 4 or 8h w/ lack of suppression at 8h diagnostic for PDH

Question 13

Test of choice for iatrogenic cushings and Addison’s disease

Answer 13

ACTH (corticotropin stimulation test)

- look for exaggerated response to ACTH

Question 14

You are trying to determine the cause of your patient’s cushings. You perform an ultrasound and see bilateral adrenal gland enlargement with a plump appearance. What do you suspect?

Answer 14

PDH

Question 15

The best test to differentiate between types of Cushing's is:
A) ultrasound
B) LDDS
C) Endogenous ACTH
D) ACTH stim

Answer 15

C - endogenous ACTH

Question 16

5 drugs that can be used to treat cushings are:

Answer 16

Mitotane
selegiline
ketoconazole
trilostane
cyproheptadine

Question 17

Which drug is a selective and irreversible inhibitor of monoamine oxidase type B?
A) Mitotane
B) Trilostane
C) Selegiline
D) Ketoconazole

Answer 17

C - selegiline

Question 18

Which drug functions competitive inhibition of 3-B hydroxysteroid dehydrogenase thus inhibiting steroids including cortisol and aldosterone?
A) Mitotane
B) Trilostane
C) Selegiline
D) Ketoconazole

Answer 18

B - trilostane

Question 19

Which drug is an anti fungal drug that lowers circulating cortisol by inhibiting steroid biosynthesis?
A) Mitotane
B) Trilostane
C) Selegiline
D) Ketoconazole

Answer 19

D - ketoconazole

Question 20

Which drug has antiserotonin, anticholinergic, and antihistamine effects?
A) Mitotane
B) Cyproheptadine
C) Selegiline
D) Ketoconazole

Answer 20

B - cyproheptadine

Question 21

Treatment of choice for adrenal tumors?
A) Drug therapy
B) adrenalectomy
C) radiation
D) transsphenoidal hypophysectomy

Answer 21

B - adrenalectomy