Endocrine II

Question 1

What are the three disorders of the pituitary-adrenal axis?

Answer 1

• Hypoadrenocorticism of the dog
• Hypersomatotropism
• (pituitary pars intermedia dysfunction

Question 2

What can cause hypercortisolaemia?

Answer 2

Usually spontaneous conditions
* Pituitary dependent hyperadrenocorticism
* Functional adrenocortical neoplasia
* Stress Induced hypercortisolaemia

Question 3

What is an iatrogenic way that an animal can get Hypercortisolaemia?

Answer 3

administration of exogenous ACTH

Question 4

How does stress induced hypercortisolaemia occur?

Answer 4

• Illness or other stress can stimulate release of CRH
• CRH stimulates more production of ACTH
• ACTH acts on adrenal glands to stimulate increased production of cortisol
• If stress is persistent you may get bilateral adrenalcortical hyperplasia

Question 5

What are the key facts surrounding hyperadrenocorticism?

Answer 5

• It is an excess production of cortisol
• The majority of cases in canines and felines are due to a pituitary adenoma

Question 6

How does a pituitary tumour effect the adrenal glands?

Answer 6

Causes an increase in ACTH, this stimulates an increased cortisol production by the adrenal glands

Question 7

What effect does an adrenal tumour have?

Answer 7

Increased production of cortisol (this is not responsive in any way to supression)

Question 8

How may you diagnose hypoadrenocorticism in a laboratory assesment?

Answer 8

• The secretion of ACTH an/ or cortisol is often pulsatile so you cannot do a basal sample
• dynamic tests have to be used for diagnostic purposes

Question 9

What is the potential issue with colecting ACTH in-vitro?

Answer 9

It is said to be labile (breaks down easily) and therefore it can be hard to obtain a required sample

Question 10

What is a common laboratory change?

Answer 10

A ‘stress leukogram’ which is made up of
* leukocytosis
* neutrophillia
* lymphopaenia
* low eosinophils

Increased lipids, increased glucose,
Urine is likely to be relatively unconcentrated

Question 11

What are the four tests you can do to test for hyperadrenocorticism?

Answer 11

• UCCR
• LDDST
• ACTH
• HDDST

Question 12

How does UCCR work?

Answer 12

Compare the creatinine that is freely filtered through the kidney to another solute
Collect a urine sample and send it for lab testing to compare creatinine and cortisol levels

Question 13

What is the meaning of the UCCR results

Answer 13

an increase in the ratio means an increased cortisol excretion in the urine and therefore increased cortisol in the blood
The test is highly sensitive
and usually used for screening only

Question 14

How does a LDDST test work?

Answer 14

• take the basal cortisol level
• administer dexamethasone (limited cross-reactivity)
• dexamethasone has the same effect on adrenal glands as cortisol

Question 15

How does an ACTH stimulation test work?

Answer 15

administer a high amount of ACTH to obtain a maximal release of cortisol from the adrenal glands

Question 16

How does a HDDST test work?

Answer 16

administration of a dose of corticosteroid should suppress
endogenous cortisol production due to the negative feedback pathways

Question 17

Why do we need to differentiate between PDH and ADH?

Answer 17

If its a unilateral adrenal mass we can then do surgery to remove it (this may not be straightforward if its an adenocarcinoma)

Question 18

In approximately how many feline DM patients is Hypersomatotropism also present?

Answer 18

around 15-25%

Question 19

How can you diagnose acromegaly (increase in GH)

Answer 19

IGF-1 appears to mirror GH well
so any increase in IGF-1 can be used as a diagnosis for hypersomatotropism

Question 20

What is the treatment for Feline Hypersomatotropism?

Answer 20

Both medical and surgical options are available
but cost is an issue for both options

Question 21

What is PPID?

Answer 21

Neoplasia of the pituitary pars intermedia
causes increased secretion of ACTH

Question 22

How may you diagnose PPID?

Answer 22

• Measurement of ACTH
• TRH stimulation test- measuring ACTH