Hypoadrenocorticism

Question 1

What are the presenting signs in dogs with Hypoadrenocorticism

Answer 1

There are NO PATHOGONOMIC clinical signs as it can affect multiple body systems. Put on your Ddx ANYTIME YOU HAVE CHRONIC GI SIGNS!

Will see most common poor appetite, lethargy, depression, vomiting, regurgitate, weight loss, diarrhea. Possibly Pu/pd, tremors, collapse, abdominal pain hematemesis, Melina, ataxia, seizures, and difficulty breathing

Question 2

What are the different types of Hypoadrenocorticism

Answer 2

Typical primary Hypoadrenocorticism (destruction of the adrenal cortex and losing both gluco and mineralocorticoids)
Atypical primary hypoadrenocorticism (destruction of adrenal cortex and having only a lack of glucocorticoids)
Secondary Hypoadrenocorticism (deficiency in ATCH production so only lack glucocorticoids)

Question 3

What tests do you do for HypoAC

Answer 3

Basal Cortisol
Considered a screening test as if it is low it can only suggest it might be hypoAC or if it is high you can rule out hypoAC

ACTH stim test
Flatline (no response to exogenous ACTH)

Question 4

How do you treat HypoAC

Answer 4

AGGRESSIVE IVF WHEN CRASHING - severe hypovolumia need to put on fluids at 40ml/kg/hr for first two hours then continue at 60ml/kg/day (monitor sodium so you do not increase it too fast)

If hyperkalemic/dysrhythmic - give calcium glutamate, insulin and dextrose
Glucocorticoid replacement (IV dexmethasone or prednisolone)
Mineralocorticoids replacement (Fludrocortisone acetate or DOCP IM for long term treatment(need to monitor for hyperaldosterone (become hypertensive and hypokalemic) seen a lot in labordoodles and will indicate a dropage of dosage)

Question 5

What are the presenting signs in a dog with Pheochromocytoma

Answer 5

Intermittent signs of weakness, hindlimb edema, collapse, abdominal dissension, anorexia, acute blindness, lethargy, epistaxis, vomiting, restlessness, adipsia

Question 6

How do you diagnose pheochromocytoma

Answer 6

Blood pressure - (25-85%) hypertension
Unremarkable CBC, biochem, or urinalysis
Can possibly see mass on CT, u/s (do have ddx of other adrenal masses)
Measure catelcholamines- urinary metabolites - normetanephrine, metanephrine, vanillymandelic acid (are more persistent than plasma metabolite norepinephrine, epinephrine)

Question 7

What are some treatment options for pheochromocytoma

Answer 7

Treat hypertension - w/ Phenoxybenzamine or prazosin
Surgical removal

Question 8

What is the rough human equivalent of hypoAC

Answer 8

Addisons

Question 9

What is hypoAC

Answer 9

Deficiency in glucocorticoids and/or mineralocorticoids

Question 10

For primary HypoAC, how much of the gland needs to be destroyed to see clinical signs and what will you see due to lacking of the hormones

Answer 10

> 90%

Lack of mineralocorticoids- inability to conserve sodium, which will cause a decreased circulating volume and hypotension. Lack of aldosterone leads to increase potassium so you get myocardial hyper excitability (which will kill the patient)

Lack of glucocorticoids- WAXING AND WANING PERIODS of impaired gluconeogenesis, hepatic glycogen depletion, impaired fat metabolism and GI sins (which worsen the inability to conserve sodium)

Question 11

What are some common causes of adrenal cortex destruction

Answer 11

Idiopathic, immune mediated, infiltrative disease (such as lymphoma and amyloidosis), hemorrhagic infarction, iatrogenic destruction

Question 12

What is the most common cause of secondary HypoAC

Answer 12

Drugs such as corticosteroids or progestogens (given with underlying hypothalamic pituitary disorders such as tumor, trauma, and congenital defects) will lead to the decreased of ATCH

Question 13

Why is secondary HypoAC not normally diagnosed (estimated cases is only 4-24%)

Answer 13

The lack of ATCH will NOT affect the mineralocorticoid production so electrolytes REMAIN THE SAME

Question 14

Signalment for HypoAC

Answer 14

Most common in young-middle age dogs (almost any age can get it with avg being 4-5yrs)
Female predisposition except in some breeds (Portuguese water dogs, bearded collie, standard poodle) with an equal sex predisposition and any breed can be affected

Question 15

How do some dogs present with hypoAC

Answer 15

More often: alert dogs- mild dehydration, recumbent dogs - severe dehydration, prolonged crt, weak pulse. Either can be depressed, thin BCS, weakness,
BRADYCARDIA (due to increased potassium interfering with ion transport and AP threshold) -> with an arrhythmia can be fatal

Question 16

What would you give a dog that is collapsed and has bradycardia +/- arrhythmia

Answer 16

1. Calcium glutamate (this will raise the AP threshold and protect the heart)
2. Dextrose and insulin (this will get potassium into cells and out of circulation)

Question 17

What are some lab findings for HypoAC

Answer 17

CBC - mild non-regenerative anemia LACKING A STRESS LEUKOGRAM
Biochem- hyperkalemia, hyponatremia, hypocholremia , sodium:potassium ratio <21:1 (below normal) (electrolyte changes in typical HypoAC), azotemia, increased bun, hypoglycemia, hypoalbuminamia, mild to moderate increases in ALT/AST
USG - typically <1.030 (low sodium causes medullary wash-out)

Question 18

What does hyperkalemia look like on an ECG

Answer 18

Mild - tented T waves due to shortened repolarization
Moderate: wide QRS complexes (Bradycardia)
Severe - (life threatening) prolonged PR intervals, absent P waves, V-fib, pulse less electrical activity

Question 19

What is pheochromocytoma

Answer 19

Neuroectodermal tumor arising from the chromaffin cells within the adrenal medulla

(Note if the tumor arises from extra-adrenal chromaffin cell it is known as a paraganglioma)

Question 20

Is Pheochromocytoma rare?

Answer 20

Yes! Only a 0.01% diagnosed neoplasia in dogs and only a few cases in cats

Question 21

Is Pheochromocytoma rare?

Answer 21

Yes! Only a 0.01% diagnosed neoplasia in dogs and only a few cases in cats

Question 22

Which type of hypoAC is more common in cats

Answer 22

Secondary HypoAC is more common, seen frequently post admin of corticosteroids or megestrol acetate

Primary HypoAC is rare

Question 23

What are the clinical signs seen with hypoAC in cats

Answer 23

Since secondary is more common you will see waxing/waning of lethargy, depression, anorexia, weight loss, collapse, weakness, dysphasia, vomiting, pu/pd (plus they are cats so the like to hide illness)