Endocrine System II

What causes Primary hypoadrenocorticism (Addisons)?

Lymphocytic inflammation of the adrenal gland

Most of ____ the adrenal cortex must be destroyed before you see clinical signs of Primary hypoadrenocorticism (Addisons)?

Both

How does atypical primary Addisons present?

Just ZF affected, mineral corticoids normal

Decrease in corticosteroids

How does secondary Addisons present?

Pituitary / Iatrogenic -> decreased ACTH atrophy of ZF and ZR

Normal mineral corticoids

Who is most likely to be affected by Addisons?

Young to middle aged female dogs

-poodles

-great danes

-westies

What might you see on a CBC of Addisons?

Lack of stress leukon in a sick pt

Mild non-regen anemia

Eosinophilia

What are common electrolyte abnormalities of Addisons?

Hyponatremia

Hyperkalemia

Hypochloremia

Na:K <25

What are some common findings on biochemical panels of Addisons?

Azotemia

Hyperphosphatemia

Hypercalcemia

Hypoglycemia

Elevated liver enzymes

Decreased albumin and cholesterol

What kind of acid base disturbance might Addisons cause?

Titrational metabolic acidosis

What U/A finding might we see w/ Addisons?

Decreased USG - below 1.030 (partially concentrated)

-Medullary wash out

Addisons is most commonly confused with what disorder?

AKI

Name a few things that can cause a decrease in the Na:K ratio?

Oliguria/ anuria -Renal dz

Uroab

Diarrhea (Whipworms/ salmonella)

Chylous effusion draining

What is a baseline cortisol used for?

R/O Addisons if above >2ug/dL

-if below do further testing

Which steroid can we administer to an Addisonian or cushanoid pt that wont affect testing?

Dexmethasone

What is the gold standard test for Addisons?

ACTH stim - fails to respond/ pre and post will be below 2ug/dL

What do we used endogenous ACTH test for in an Addisons pt?

Diff Atypical Addisons vs/ secondary Addisons

An endogenous ACTH test for an addisonian pt should not be done if?

Pt does not have concurrent hyponatremia or hyperkalemia

A increased endogenous ACTH test is suggestive of _____ Addisons and a low to normal endogenous ACTH test is suggestive of ___ Addisons?

Atypical primary addisons

Secondary hypoadrenocorticism

What is the most common form of hyperadrenocorticism (cushings)

Pituitary dependent

Who is most likely to get cushings?

Middle aged to older

-poodles

-boxers

-dachshunds

What are common CBC findings of Cushings?

Stress leukon

Erythrocytosis

Thrombocytosis

What are common U/A findings of Cushings?

Decreased USG/ Partially concentrated

Proteinuria

UTI

What are common biochemical findings of Cushings?

Increased ALP (C-ALP)

Hyperlipidemia

Hyperglycemia

Hypophosphatemia

DEcreaed/ low normal BUN

When should we not test for cushings?

No clin signs

Concurrent non-adrenal illness

Identify if the following is a screening or discriminatory test for HAC (Cushings) ?

ACTH stim test

Screening - can dx

Identify if the following is a screening or discriminatory test for HAC (Cushings) ?

Low dose dex suppression test

Screening - can dx

Identify if the following is a screening or discriminatory test for HAC (Cushings) ?

Urine cortisol: urine creatinine ratio

Screening only

Identify if the following is a screening or discriminatory test for HAC (Cushings) ?

High dose dex suppression test

Discriminatory

Identify if the following is a screening or discriminatory test for HAC (Cushings) ?

Exogenous ACTH

Discriminatory

Identify if the following is a screening or discriminatory test for HAC (Cushings) ?

Advance imaging

Discriminatory

What test should never be used by itself for a HAC dx?

Baseline cortisol

What do we expect w/ an ACTH stim test w/ HAC?

Exaggerated response to ACTH

What can cause false positives to ACTH stim tests w/ HAC?

Stress - illness/ environment

If you have iatrogenic HAC what would you expect to see on ACTH stim test?

Plateau wont change much

True or false:

A negative ACTH stim test can R/O HAC

False

A dog w/ HAC after a Low dose dex suppression test will typically not respond to the neg feed back at ___hr mark

8hr

A dog w/ HAC that is suppressed at 4hr and escapes at 8hrs is suggestive of what?

PDH

If the 4 or 8 hr samples in a LDDST is less than ___ of baseline cortisol it is suggestive of PDH cause?

50%

Urine cortisol : urine creatinine ratio can rule ____ cushings?

out

If too high do other tests (collect urine at home)

The LDDST is more ____ where as the ACTH test is more ___?

Sensitive (Less false negative)

Specific (less false positives)

Discriminatory tests should only be used when?

After HAC dx is made - diff between pituitary and adrenal dependent

What qualifications of a HDDST would we say that HAC is pituitary in nature?

Suppressed at 8hrs

Suppressed at 4hrs

Below 50% of baseline cortisol at 4 or 8hrs

When sampling Endogenous ACTH if it is high it is ____ dependent cushings, if it is low then it is ____ dependent cushings?

Pituitary

Adrenal

If HDDST does not meet the cut offs for PDH can we dx adrenal tumors?

No still could be pituitary dependent - do imaging