Hypercortisolism Flashcards by Emily Wirth

What does Cushing’s syndrome describe?

Chronic exposure to excess glucocorticoids (cortisol)

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What is the glucocorticoid released by the adrenal cortices?

Cortisol

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What is cortisol release controlled by?

ACTH release from the pituitary gland

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What is ACTH release determined by?

CRH from the hypothalamus

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What form of spontaneous HC is most common?

Pituitary dependent hypercortisolism (PDH)

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What type of dogs is PDH more commonly seen in?

Small dogs
(mini poodle, dachshund, beagle, boston)

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Where is the tumor in PDH?

Anterior pituitary

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What does chronic stimulation by ACTH in PDH cause?

Bilateral adrenal enlargement

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What breed of dogs are predisposed to AT?

German Shepherds

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What would the expected endogenous ACTH release be in AT?

Very low due to negative feedback

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What happens to the contra-lateral adrenal gland in AT?

Becomes atrophied

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Cushing’s is:

An exam room diagnosis
Must see signs and have appropriate history

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What are the signs of HC?

Polyuria
Polydipsia
Polyphagia
Difficulty jumping
Pot-bellied appearance
Stretching of carpal and tarsal ligaments
Bad hair coat

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Where would you expect the lowest point of the abdomen to be in a HC patient?

The liver
Cranial abdominal organomegaly
Very consistent finding in HC dogs

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What skin condition would be pathognomonic for HC?

Calcinosis cutis

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What are potential consequences of HC?

Chronic infections
Poor healing post injury or surgery
Hypertension
Proteinuria
Pulmonary thromboembolism
Decrepitude
Poor quality of life

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Only pursue a work-up for HC if one of the following applies:

Owner has a complaint
Clinical impression
Medical issue suggests HC

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What findings on a CBC would be supportive of HC in a clinical patient?

Stress leukogram (neutrophilia, lymphopenia, monocytosis, eosinopenia)
Hematocrit is often increased
Platelets are often increased

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What findings on a chemistry would be supportive of HC in a clinical patient?

Elevated ALP is the most consistent finding in dogs (usually 10-20x baseline)
Cholesterol is elevated (~350-380)
(Less consistently: mild elevation in glucose, BUN may be low, elevation in phosphorus)

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What findings on urine analysis would be supportive of HC in a clinical patient?

Urine is usually dilute
UTI is common
Significant proteinuria is common

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How long should you discontinue use of oral and topical steroids before adrenal testing?

> 72 hours

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How long should you discontinue use of depo shots before adrenal testing?

> 4 weeks

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When is the ACTH stim test routinely used for?

Monitoring of patients on treatment for HC

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What will show an exaggerated response to the ACTH stim test?

Dogs with HC, chronic non-adrenal illness, dogs with AT (sometimes - can also be normal or flat line)

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Why can the ACTH stim test be negative in dogs with AT?

The tumor may not have receptors for ACTH

Is the ACTH stim test good for cats?

No, very inaccurate

What is the protocol for the ACTH stim test?

Obtain a baseline blood sample, inject 5 micrograms/kg IM of cosyntropin, collect second serum sample after 60 mins

How do you interpret an ACTH stim test?

Normal dogs are usually between 7-17 micrograms/dl Post-ACTH stim cortisol >22 micrograms/dl indicates HC in a dog A flat line response (pre and post are <5 micrograms/dl) in a dog with signs of HC indicates iatrogenic disease or may be seen in AT

What does the LDDST investigate?

The feed-back loop between the adrenals and pituitary/hypothalamus

If the HPA axis is working appropriately, what should dexamethasone do?

Suppress CRF from the hypothalamus thereby stopping ACTH release by the pituitary gland

How long should cortisol release by the adrenals be stopped after administering dexamethasone?

At least 12 hours

With PDH, what should be expected after administration of dexamethasone?

Pituitary tumor is transiently inhibited or not affected at all by the dex Cortisol production is evident at 8 hours post dose

With an AT, what should be expected after administration of dexamethasone?

No inhibition of cortisol production Cortisol production continues unchanged over the 8 hours

What is the protocol for a LDDST?

Obtain a baseline blood sample, inject dexamethasone IV (0.01 mg/kg in dogs; 0.1 mg/kg in cats), collect second blood sample 4 hours later, collect third blood sample 8 hours later

What does a baseline cortisol tell you?

Nothing

How do you interpret a LDDST?

Look at the 8 hour value first <1.4 mcg/dl indicates suppression of the HPA axis >1.4 mcg/dl indicates HPA axis dysfunction If the 8 hour value was >1.4 mcg/dl, look at the 4 hour value <1.4 mcg/dl or <50% of baseline at 4 hours indicates PDH

Can you assume a dog has an AT if there is no suppression?

What test is generally regarded as superior to the ACTH stim test in dogs?

LDDST

What is the test of choice for cats with HC?

LDDST

What can you determine by a urine cortisol : creatinine ratio?

A normal result essentially rules out HC

What would you expect to see on ultrasonography of PDH?

Bilateral adrenal gland enlargement Generally, fairly symmetrical Some nodular changes are common

What would you expect to see on ultrasonography of a AT?

One large gland Check for mets and invasion of surrounding structures May note atrophied gland on the other side

What might radiography reveal?

AT, 50% are calcified and are visible on a lateral view

Does calcification of an AT indicate malignant potential?

What would you expect the endogenous ACTH level to be in PDH?

Elevated or normal

What would you expect the endogenous ACTH level to be in an AT?

Very low or undetectable

What is the current standard approach in dogs for PDH?

Medical therapy

What is the MOA for Trilostane?

Reversible enzyme inhibitor Inhibits 3bHSD

What is 3bHSB essential for?

Synthesis of cortisol from cholesterol

How long does Trilostane last?

About 18 hours in most dogs Administered with food in the morning

What is the recommended dosing?

Once daily for most dogs BID in diabetics BID if the effect wears off too soon (escape at night)

What is the recommended daily dose to start with?

2-3 mg/kg total daily dose Round down to nearest capsule size

What is the recommended recheck schedule?

2 weeks after starting, 2-4 weeks later, 3 months later, and then every 4-6 months long term

What should you always do if the dog is unwell on recheck?

ACTH stim test

What might you see on a chem during a recheck and what does it indicate?

Increased potassium, indicates suppression of aldosterone, must decrease trilostane dose

If you get a result <0.7 mcg/dl in a post-acth stim cortisol what would you do?

Stop trilostane and do not restart until patient shows signs of HC

If you get a result 0.7-2.0 mcg/dl in a post-acth stim cortisol what would you do?

Stop trilostane for 48 hours, restart at 50% of previous dose

If you get a result 2.0-7.0 mcg/dl in a post-acth stim cortisol what would you do?

Continue at present dose

If you get a result >7 mcg/dl in a post-acth stim cortisol what would you do?

Consider a 25-50% increase if patient shows signs of HC

If the patient is clinically doing well, what tests might you run to ensure dosing is correct?

4 hr post dose cortisol or pre-trilostane cortisol

If you get a result >5.5 mcg/dl on a 4 hr post dose cortisol, what would you do?

Increase the dose by 25-50%

If you get a result >5 mcg/dl on a pre-trilostane cortisol, what would you do?

Increase dose by 25-50%

If you get a result >3 mcg/dl on a pre-trilostane cortisol with clinical signs, what would you do?

Increase dose by 25%

What is the most important factor when deciding about dose adjustments?

Clinical status

What are you going to do if a dog becomes ill on trilostane?

Stop trilostane, check electrolytes to rule out adrenal necrosis, do an ACTH stim test to assess adrenal function

What are the options for treatment of an AT?

Surgery Medical therapy (Trilostane)

What is feline hyperadrenocorticism associated with?

Diabetes mellitus

What are the clinical signs of HC in a cat?

Unlikely to be pu/pd unless diabetic Eat well but not ravenous Skin issues are common - FRAGILE Ventral alopecia Plantigrade stance Pot-belly appearance Folded ear tips (pathognomonic, uncommon)

What laboratory changes are common in cats with HC?

Variable hyperglycemia Hypercholesterolemia NO increase in ALP

Hypercortisolism Flashcards

(69 cards)