Hyperadrenocorticism testing..

how do you diagnose HAC

Why can you not just test for cotisol in HAC

• Can go up for many reasons + goes up with stress.

• fluctuates throughout the day - morning peak

• Additionally cannot just test for cushings - must have a high index of suspiction, e.g. Pu/pd/..

What steps will you go through in order to determine glucose..

1) BLood biochemistry + haemotolgy

2) Urinalysis

3) Imagain

4) DIAGNOSTIC TEST..

Many things will increase this index suspicion…

What is the key biochemical abmormaility you would expect in cushings cases..

HIGH ALP… 90% of dogs with cushings will have a high ALP///

What are the 6 biochemical abnormalities you can suspect with cushings…(5 up one done)

• high ALP (90%)

• ALT

• cholestrol

• bile acids

• fasting gluvose

• LOWER urea

Why does ALP go up…

As dogs have a corticosteroid dependent ALP which will increase in the present of cortisol

What will happen to neutrohils and eosinophils in terms of haematology..

1) Neutrophilia (high neutrophils)

2 )Ly,phopenia (low lymphocytes)

This is due to immune system suppression and lack of marginalisation.. Eosinopenia and monocytosis is also present

N>B> Cytosis = high cells of that type…

What is the standard USG in dogs..

0.008 - 0.0012/5

this is isotrouric as same conc as plasma…

UTIs= steroids causeing few inflammatory respones..

very concentration is above o.o30//

What is teh normal sizeof adrenal glands..

25mm - 5 mm

What will be the ultrasonographic image of a pituatory dependent HAC

2x hyperplastic adrenal glands, bilateral..

what will be the ultrasonographic adrenal findings for a pituatory dependent HAC

unilateral adrenal gland enlargment… due to an adrena tumour..

What 5 radiograph abdominal radiographs are you likely too see..

• Hepatomegaly

• Pot-bellied appearance

• calcinosis cutis

• distended bladder

• adrenal enlargment/ calcification

What 3 abnormalities are you likely too see on thoracic radiographs

• Tracheal and

• vess

What is Sensitivity

Refers to the tests ability to accuratly test those animals which are positive AS positve results….

e.g. if it tests positive does it actually have that disease..

Therefore sensitivity is good for ruling things out

this is becuase if a test is highly sensitive, if it tests positive then it will be positive.

Therefore if an animals is tested and tests negative you can rule it out, this is becuause a positive result would definietyly test positive..

What is specificity..

Normal animal will test negative. TRUE negaitives proportion of those that are tested which are true negative.s.

What is the 2 step process for HAC diagnosis

1) is there evidence for hyperadrenocorticism

2) Does the animal have pituitary-dependent or adrenal dependent hyperadrenocorticism

WHat are the 3 screening tests we can use to initially assess whether an animal has hyperadrenocorticism…

1) Urinary cortisol: creatinine ratio

2) ACTH stimulation test

3) Low dose dexamethasone suppression test (LDDS)

HOw does the urinary cortisol: creatinine ratio test work..

• Measure the cortisol (which fluctuates so measure AGAINST creatinine as not absorbed or secreted..

• very sensitive… If there is a low ratio then HAC is EXTREMELY unlikely. This is becuase one of the fundamental features of HAC is the fact it has high cortisol…

HOWEVER… If low specifity then will be negative..

What is the ACTH stimulation. test..

• measure cortisol

• inject ACTH (synthetic)

• measure cortisol again..

ACTH stimulates cortisol, however if cushingoid should have an exagerated response, this is because the adrenal glands are overactive so will produce a lot of cortisol… OR the pituatory glands are overfiring ACTH anwya so it is a double over firings…

What does IATrogenic cushings look like

no endogenous cortisol is produced.

What is the positve result for acth stim

above 600 nmol

evalation of aCTH

very sensitive

LDDS test

• inject cortisol synthetic, should negative feedback after starve over night

• check for cortisol

• starve overnight then check again…should reduce overnight but in cushingoid test, the tumour is over producing…

What result would you expect from an LDDS test

• A reduction in the amount of cortisol present in the blood, the fake cortisol should trigger negative feedback mechanisms to reduce the amount of cortisol over approx 8 hours.

• A diseased result is greater than 50 nmol/ 8 hours

Ldds PDH result…

greater than 50% supression after 3 hours

hypothalamus will stop producing acth and this will reduce

ldds supressions…

ldds

• more senesitive

• low specificity..

How do you select a test…

How do you differentiate between ADH and pdh

• High dose dexamethasone test

• endogenous acth

• adrenal imaging

• pituitary imaging

HDDS test..

• high test.. see if we can force pituatory to reduce…

Endogenous ACTH test..

• pituatory tumour increases ACTH levels.

• 
  

• BUT if an adrenal tumour the negative feedback will still work and ACTH level swill decrease..

How can you carry out adrenal imaging

pituatory imaging

very expensice, CT or MRI… normal vs enlarged is not clearly defined…

Summary

equine v canine HAC