Hypoadrenocorticism

Question 1

What is the definition of hypoadrenocorticism?

Answer 1

Disorder resulting in marked adrenocorticolysis, usually immune mediated

Question 2

Results in reduced capacity to produce…

Answer 2

Cortisol and aldosterone

Question 3

Is it always clinically significant?

Answer 3

no, some not clin sig

Question 4

Do all cases have electrolyte disturbances?

Answer 4

No, non-typical hypoA has no electrolyte disturbances

Question 5

what is critical illness related corticosteroid insufficiency? (CIRCI)

Answer 5

Critically ill animals which are unable to produce adequate cortisol to deal with their illness. Can’t therefore recover from their illness

Question 6

What is typical hypoadrenocorticism characterised by?

Answer 6

reduced capacity to produce cortisol AND aldosterone

Question 7

What is atypical hypoadrenocorticism characterised by?

Answer 7

Glucocorticoid deficiency only

Question 8

What are the two main reasons for adrenocorticolysis

Answer 8

Immune mediated destruction

Increased ACTH –> haemorrhage and necrosis of adrenal

Question 9

What is the typical signalment?

Answer 9

Young to middle aged dogs, more uncommon but does happen in middle aged cats
More common in females in dogs

Question 10

What breeds are predisposed?

Answer 10

Standard poodle
Bearded Collie
Leonburgers
NSDT (Nova Scotia Duck Tolling) retrievers (the ones with the webbed feet)

Question 11

What are the two clinical pictures with hypoA

Answer 11

Acutely collapsed severely compromised patient

Variably subtle ‘unwell’ animal, presents because not quite himself, waxes and wanes

Question 12

How does the severely compromised hyoA patient present?

Answer 12

hypovolaemic and/or dehydrated
Poor circulatory volume-shock
Tachycardic or bradycardic or neither..
may be sudden on set or after relapsing more subtle set of problems

Question 13

Why might they be tachycardic?

Answer 13

hypovolaemia

Question 14

Why might they be bradycardic?

Answer 14

hyperkalaemia

Question 15

Why does melena happen with hypoA

Answer 15

hypoA causes structural GIT problems

Question 16

What will a gut biopsy from a hypoA dog be interpreted as?

Answer 16

IBD

Question 17

Clin signs are non specific: decreased appetite, decreased exercise tolerance, depressed etc

Answer 17

non specific but a key differential as a very important and severe disease!

Question 18

What are the common clinpath signs with hypoA?

Answer 18

possible mild anaemia, may be regenerative (melena bleeding), or non regenerative (anemia of chronic disease)
Hypoproteinaemia (pan) due to bleeding into gut
Absence or opposite of stress leukogram - eosinophilia, lymphoctosis
Azotaemia as hypovolaemic
Hyponatraemia and/or hyperkalaemia
Hypercalcaemia
hypoglycaemia

Question 19

Why do you get the structural gut disease?

Answer 19

Lysosomal instability as lack of glucocorticoids

Question 20

Why do you have inappropriately dilute urine?

Answer 20

Hyponatraemia - countercurrent doesn’t work so can’t concentrate urine

Question 21

What tends to happen to electrolytes in hypoA?

Answer 21

Low serum sodium, high serum potassium as lacking ALDOSTERONE so can’t exchange in DCT of nephron

Question 22

Is sodium potassium ratio diagnostic?

Answer 22

No!

Question 23

Why is it such a bummer if you miss this disease?

Answer 23

Young dogs, easily treatable disease

Question 24

What is the best way of assessing this disease?

Answer 24

ACTH stimulation test
Basal cortisol test if this not possible.
make sure hasn’t had any exogenous GC given! will mess up result

Question 25

What is tetracosactide?

Answer 25

Synthetic ACTH. Used for ACTH stim test

Question 26

How should you treat the severely compromised hypoA patient?

Answer 26

Supportive fluid therapy (but be careful as particularly fluid sensitive)
IV Hormone supplementation, must have good glucocorticoid AND mineralocorticoid activity

Question 27

What is the maximum fluid dose rate you can give a hypoA patient?

Answer 27

7-8ml/kg/hr

Question 28

Do you want to give short or long acting hormone replacement in the addisonian patient?

Answer 28

Short acting, i.e. NOT dex

Question 29

What is the hormone replacement of choice? (drug name)

Answer 29

Hydrocortisone sodium succinate

Question 30

Why must you not give dexamethasone in the addisonian situation?

Answer 30

Half life of 40 hours, if you give it and it hasn’t got hypoA it’s going to now have a long acting GC that’s going to potentially cause gut damage. It’s a very potent GC and has no MC activity

Question 31

When do you move them onto oral treatment?

Answer 31

Once they start eating and drinking (usually within 36 hours)

Question 32

What is the treatment for a patient with the chronic clinical picture?

Answer 32

Suitable balanced glucocorticoid and mineralocorticoid supplementation

Question 33

What drugs are available for oral supplementation?

Answer 33

Fludrocortisone (MC and GC activity)
Often need to supplement with either
Cortisone acetate
or 
Prednisolone

Question 34

What dietary conditions should you consider?

Answer 34

Added salt

Question 35

What is the normal cortisol production in the dog?

Answer 35

0.2mg/kg/24h

Question 36

How do you work out how much you should supplement the dog with?

Answer 36

Work out how much the body would produce (0.2mg/kg/day)

Pred is around 5x as potent as the body’s own GC so divide the amount by 5

Question 37

Why might you get altered gait when treating for hypoA?

Answer 37

pseudomyetonia from iatrogenic overdose

Question 38

What other drugs can we use to manage stable patients?

Answer 38

Can use hydrocortisone acetate

Question 39

How do you supplement atypical hypoA?

Answer 39

GC supplementation only

Question 40

How do you monitor response?

Answer 40

Clinical picture improving
Check for stress leukogram
Sodium and potassium levels

ACTH stim/basal ACTH unnecessary and expensive