HAC diagnostic testing (smallies)

Question 1

what biochemical abnormalities suggest hyperadrenocorticism

Answer 1

• Marked ALP increase!
• mild-moderate increase in ALT
• increased cholesterol
• mild to moderate increase in bile acids
• high fasting glucose
• low urea (BUN)

Question 2

what abnormalities of a CBC would suggest HAC

Answer 2

stress leukogram
- high neutrophils
- low lymphocytes
- low eosinophils
- high monocytes

Question 3

what would you expect to see on urinalysis of a dog with HAC

Answer 3

• low USG (often <1.015
• evidence of UTI

Question 4

what physical/imaging abnormallities might you see in a dog with HAC

Answer 4

• hepatomegaly
• pot bellied appearance
• calcinosis cutis
• distended bladder
• adrenal enlargement/calcification
• tracheal and bronchial wall mineralisation
• pulmonary metastasis
• osteoporosis

rads no most useful diagnostic tool but might be helpful in less obvious cases

Question 5

on ultrasound, what would the normal adrenal gland look like and what will it look like if abnormal

Answer 5

• normal = 25mm x 5mm
• hyperplastic adrenals are larger but have a normal echogenicity
• compare size of both, if one larger than the other, assume ADH

Question 6

what are the 3 HAC screening tests

Answer 6

• urinary cortisol:creatinine ration
• ACTH stim
• Low dose dexamethasone suppression

Question 7

explain the process of urinary cortisol:creatinine testing and explain pros and cons. what would you expect to see if you expect HAC

Answer 7

• easy to perform
• high sensitivity, low specificity (false +, few false -)
• low ratio makes HAC extremely unlikely (low cortisol high creatinine

Question 8

describe the ACTH stim test, what are the pros and cons and what should you see in a healthy vs diseased animal

Answer 8

protocol:
- starve overnight
- test plasma cortisol at time 0
- inject synthetic ACTH iv
- collect second sample 60 minutes later

results:
- normal: cortisol levels should increase
- abnormal: cortiso levels increase beyond what is normal (super high)

• decent sensitivity
• best specificity (few false +)
• expensive
• quick and easy

injecting exogenous ACTH results in increased cortisol release from the adrenal gland

Question 9

describe the LDDS test, pros and cons and what you would expect to see

Answer 9

• requires prolonged hospital stay
• injecting exogenous glucocorticoid results in reduced ACTH due to negative feedback
• expect reduced cortisol release from the adrenal gland
• get a reduced or absent response in most dogs with spontaneous HAC
• high sensitivity
• low specificity

protocol:
- starve overnight
- measure baseline plasma cortisol
- inject dexamethasone iv
- measure cortisol at 3 and 8 hours

Question 10

what are the differences in disease between ADH and PDH

Answer 10

• dogs with ADH normally more resistant to medical management
• prognosis for PDH is normally better than for ADH
• for dogs with ADH which are resistant to tx, adrenalectomy is an option
• PDH can lead to neuro signs

Question 11

why dont we use HDDS test

Answer 11

because tumours react to it differently and it might not be accurate

Question 12

what do you expect to see of the adrenals on US in PDH vs ADH

Answer 12

PDH: symmetrically enlarged and normal conformation
ADH: one enlarged gland and one atrophied gland