Hyperadrenocorticism Flashcards

1
Q

What is Canine Cushing’s Syndrome?

A

The constellation of clinical sings/abnormalities resulting from chronic glucocorticoid exposure caused by a tumor in the pituitary (80-85%) or adrenal glands.

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2
Q

Etiology of pituitary dependent hyperadrenocorticism

A

Excess production of ACTH with loss of negative feedback control on the pituitary

Frequency and amplitude of ACTH secretion is increased

Results in bilateral hyperplasia of the adrenal glands

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3
Q

Etiology of adrenal dependent hyperadrenocorticism

A

Excessive production of cortisol

Causes negative feedback on the pituitary resulting in suppression of ACTH production

Tumors function independently of hypothalamic/pituitary control

Usually unilateral adrenal involvement - uninvolved adrenal gland develops cortical atrophy as it receives no ACTH stim as a result of negative feedback

Tumor cells in the adrenal gland retain ACTH receptors and therefore may respond to exogenous ACTH

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4
Q

Signalment for hyperadrenocorticism

A

Mainly dogs
Any breed usually middle aged
More females
PDH - more common in small/toy breeds
ADH - affects large breed dogs more frequently

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5
Q

Prognosis for hyperadrenocorticism

A

Degree of ALP elevations does not reflect severity of disease or response to treatment

Pituitary microadenomas - good long term prognosis
Pituitary macroadenomas - poor without treatment; fair with effective treatment
Adrenal tumors - good to poor depending on type and tx

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6
Q

Treatment options for adrenal dependent hyperadrenocorticism

A

Medical
- Trilostane or Mitotane

Surgical
- Adrenalectomy
- can still reoccur in other adrenal gland or can later develop PDH

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7
Q

Goals of treatment for hyperadrenocorticism

A

Improve quality of life
Eliminate clinical signs
Avoid adverse effects

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8
Q

Medical is treatment of choice for _________ dependent hyperadrenocorticism, and surgical is the the treatment of choice for ___________ dependent hyperadrenocorticism.

A

Medical - pituitary
Surgical - adrenal

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9
Q

This drug is a chemotherapeutic agent used to treat pituitary dependent hyperadrenocorticism.

A

Mitotane - adrenolytic; selective necrosis in the zona fasciulata and zona reticular is, often sparing the zona glomerulosa

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10
Q

Adverse effects of Mitotane

A

Hypoadrenocorticism
Drug induced CNS signs
Can be very severe

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11
Q

This drug used to treat pituitary dependent hyperadrenocorticism is a synthetic steroid analog; enzyme inhibitor that prevents formation of cortisol; competitively inhibits 3 beta hydroxy steroid dehydrogenase

A

Trilostane

Effects are reversible and dose dependent

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12
Q

Adverse effects of Trilostane

A

Hypoadrenocorticism
Idiosyncratic adrenal necrosis
GI upset
Mild electrolyte abnormalities due to partial inhibition of aldosterone
Risk of death due to Addisonian crisis

More user friendly but very expensive
Only use Vetoryl brand - compounded has poor efficacy

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13
Q

Protocol for administering Trilostane to treat hyperadrenocorticism

A

Begin Trilostane tx generally at 1 mg/kg BID or 2 mg/kg SID (increased absorption when given with food)

Recheck ACTH stim / electrolytes at 14 and 30 days and adjust dose as needed

Recheck ACTH stim 10-14 days after any dose adjustment

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14
Q

Are selegilene (MAO inhibitor) and ketoconazole (inhibits steroid production) considered effective treatments for pituitary dependent hyperadrenocorticism?

A

No

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15
Q

DFDX for an adrenal tumor

A

Functional adenoma - producing cortisol
Nonfunctional adenoma - doing nothing
Cortical adenocarcinoma - may be functional
Pheochromocytoma - medullary tumor producing catecholamines
Other - metastasis

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16
Q

What are the most common clinical signs of hyperadrenocorticism?

A

PU/PD
Polyphagia
Panting
(P)Alopecia
(P)Abdominal enlargement

17
Q

Dermatologic problems seen with hyperadrenocorticism

A

Truncal alopecia
Thin skin, easily bruised
Difficulty healing - collagen inhibition
Recurrent pyodermas - immune suppression
Adult onset demodicosus - immune suppression
Calcinosis cutis - only in dogs
Cutaneous hyperpigmentation

18
Q

Urinary signs of hyperadrenocorticism

A

PU/PD - most common presenting complaint; blocks action of ADH at collecting tubules

Recurrent UTIs - due to presence of dilute urine and poor immune response; recommend urine cultures

19
Q

Muskuloskeletal signs of hyperadrenocorticism

A

Generalized weakness
Muscle wasting - protein catabolism, collagen breakdown

20
Q

What causes abdominal distention in patients with hyperadrenocorticism?

A

Fat redistribution
Hepatomegaly - increased glycogen storage
Weak abdominal muscles

21
Q

Respiratory signs of hyperadrenocorticism

A

Panting - muscle weakness, pressure on diaphragm bony enlarged liver a and abdominal fat accumulation, pulmonary mineralization

If severe dyspnea is seen, suspect pulmonary thromboembolism (PTE) - glucocorticoid induced hypercoagulability

22
Q

Complications/infections associated with hyperadrenocorticism

A

Hypertension
Pyelonephritis / UTIs
Pancreatitis
Urinary calculi
Gallbladder mucocele
DM - push pre-diabetic animals into full diabetes by causing insulin resistance
Hypercoagulability - pulmonary thromboembolism

23
Q

Neurologic signs caused by compression by pituitary mass - macroadenoma

A

Inappetance / anorexia - most common
Dullness - most common
Disorientation
Circling
Ataxia
Behavioral changes