Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Module 17 > Hyperadrenocorticism > Flashcards

Hyperadrenocorticism Flashcards

1
Q

what are the causes of hyperadrenocorticism

A

Spontaneous:Pituitary dependent: 85%

Pituitary tumour: >90%

Adrenal dependent

Adrenal tumour: >90%

Iatrogenic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is the pathophysiology of pituitary dependent HAC

A

Functional adrenocorticotropic hormone (ACTH) secreting pituitary tumour in approx. 85% of dogs

  1. Excessive secretion of ACTH causes bilateral adrenocortical hyperplasia and excess cortisol secretion from the adrenal cortex
  2. Because normal feedback inhibitor of ACTH secretion by cortisol is missing excessive ACTH secretion persists despite increased adrenocortical secretion of cortisol
  3. Episodic secretion of ACTH and cortisol is common and results in fluctuating plasma concentrations that at times may be in the reference range
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

how is HAC diagnosed

A
  1. clinical signs
  2. screening tests
  3. specific tests: confirming, identifying the cause
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is the signalment of HAC (5)

A
  1. Typically in dogs 6 years and older (median 10 years) but can be in younger dogs
  2. No sex predisposition (but ADH may be more common in female dogs)
  3. Poodle, Dachsunds, Terriers, GSD, Boxers, Boston terriers
  4. PDH more common in small dogs
  5. ADH more common in larger dogs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are the most common clinical signs of HAC (7)

A
  1. Polyuria, polydipsia, polyphagia
  2. Respiratory signs: panting
  3. Abdominal enlargement
  4. Endocrine alopecia
  5. Mild muscle weakness
  6. Lethargy
  7. obesity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are the dermatological changes seen in HAC (3)

A
  1. Non-pruritic truncal alopecia
  2. Thin skin
  3. Failure to regrow shaved hair
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what are uncommon clinical signs seen in HAC (7)

A
  1. Suppression of pituitary function –> persistent anestrus, testicular atrophy, secondary hypothyroidism
  2. Laxity of ligaments may lead to lameness
  3. Hypercoagulability may result in formation of spontaneous thrombi, typically involving pulmonary vessels and resulting in acute resp distress
  4. Cortisol insulin resistance
  5. Persistent hypertension
  6. Neurological signs: obtunded, dopey, fall asleep, apparently blind
  7. Myotonia: relaxation of muscle is impaired
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is iatrogenic HAC

A

too long of steroid course

make sure you search in history if there has been steroid use

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what can be seen on serum bioch with HAC (6)

A
  1. increased ALP: steroid induced production
  2. increased cholesterol
  3. increased glucose (only slightly)
  4. increased ALT, GGT, AST (won’t increase to the extent of ALP)
  5. increased bile salts (steroid hepatopathy)
  6. decreased urea and creatinine (PUPD)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what can be seen on hematology in HAC

A

stress leukogram

  • neutrophilia
  • lymphopenia
  • eosinophilia
  • monocyotosis
  • erthrocytosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what can be seen in urinalysis HAC (4)

A
  1. low SG (< 1.020)
  2. proteinuria
  3. urinary tract infection
  4. glucosuria
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what radiographic changes can be seen in HAC (2)

A
  1. many changes largely non-specific
  2. prognostic important: adrenal masses, thoracic metastases, intercurrent disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is the principle of the ACTH stimulation tests

A

ACTH stimulates adrenal cortex to maxillary secrete cortisol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

how is an ACTH stimulation test done (3)

A
  1. take blood sample for basal cortisol
  2. administer 0.2 mg ACTH IV or IM
  3. take second blood sample 0.5-2 hours
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the sensitivity with ACTH stimulation

A

only 50% of dogs with AD-HAC will be indentified

only 85% of dogs with PD-HAC will be identified

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

how do you interpret the results of ACTH stimulation test

A

Dogs with hyperadrenocorticism have an increased post-ACTH admin cortisol increase

The absence of a response is suggestive of adrenocortical neoplasia or iatrogenic hyperadrenocorticism

17
Q

what is the priniciple of low dose dexamethasone suppression test

A

Dexamethasone suppresses ACTH secretion

Rapid recovery, or failure to suppress, in HAC

18
Q

how is a low dose dexamethasone test done (3)

A
  1. take blood sample for basal cortisol
  2. administer 0.015 mg/kg dexamethasone IV
  3. take blood sample 3 and 8 hours later
19
Q

how do you interpret the results of a low dose dexamethasone suppression test

A

in an AD/PD-HAC dog dexamethasone will not suppress cortisol at all

in a PD-HAC dog it will be able to suppress it for some time but then cortisol levels will increase again

normal dogs will suppress cortisol

20
Q

what other tests can diagnose HAC (2)

A
  1. 17 hydroxyprogesterone: cortisol precursor
  2. urine corticoid:creatinine ratio approximation of 24 hour total urine cortisol
21
Q

what is an ACTH assay used for

A

to identify the cause of HAC

22
Q

how is an ACTH assay done

A

ACTH decays very quickly at room temp

send frozen EDTA plasma to a specialist lab

23
Q

how is an ACTH assay interpreted

A

PD-HAC results in increased ACTH concentrations

AD-HAC results in suppression of ACTH secretion

24
Q

is HAC common in cats

A

no its rare

25
Q

what is another name for HAC

A

Cushing’s

26
Q

what are the clinical characteristics of HAC in cats

A

Similar to those seen in dogs

Differences:

Strong association with diabetes mellitus

Progressive relentless weight loss leading to cachexia

Dermal and epidermal atrophy leading to extremely fragile, thin and easily torn and ulcerated skin

27
Q

how is PD-HAC treated (5)

A
  1. trilostane (steroid enzyme inhibitor)
  2. mitotate (adrenolytic)
  3. ketoconazole (steroid enzyme inhibitor)
  4. I-Deprenyl (MAO-type B inhibitor)
  5. hypophysectomy
28
Q

how is AD-HAC treated (3)

A
  1. trilostane
  2. mitotane
  3. unilateral adrenalectomy
29
Q

what are the effects of trilostane

A

Competitive inhibitor of 3-B-hydroxysteroid dehydrogenase which mediates the conversion of cholesterol into cortisol

The net effect is inhibition cortisol, aldosterone and progesterone production

30
Q

how long acting is trilostane

A

Relatively short acting:

Most dogs break out of suppression after 12 hours

31
Q

what is the initial dose of trilostane

A

2mg/kg q 25h by mouth

accurate dosing can be difficult with capsules –> generally go up

32
Q

what are mild complications that can occur with trilostane

A

Mild:Electrolyte abnormalities

Inconsequential

Diarrhea, lethargy, anorexia, vomiting

33
Q

what are serious consequences of trilostane

A

Hypoadrenocorticism

Some can die

Most respond to appropriate therapy

34
Q

what are the clinical signs that you should advise owners to monitor when their dog is treated with trilostane

A

Polyuria/polydipsia, polyphagia, lethargy

Alopecia, panting, pot-belly

35
Q

how often should you monitor HAC with a ACTH stimulation test

A

10-14d

1 month

every 3-4 months

start 2-4 hours after treatment

36
Q

what is pre-vetoryl cortisol and how is it used

A

Book appointment just before dog’s next trilostane is due

If the dog is normally given trilostane at inconvenient time then ask the owner to give at a convenient time at least the day before

Take history and quickly examine the dog

Make sure owner has not given trilostane and that nothing stressful has happened this morning (vomiting, injury)

Sample

Take sample immediately after exam

1-2ml of blood in heparin or serum tube

Can be separated and stored for up 1 week

Send to external lab

37
Q

how do you interpret the results of pre-vetoryl cortisol

A
38
Q

which is better SID, BID trilostane

A

twice daily is better for clinical signs

Module 17 (31 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions