Hypoadrenocorticism

Question 1

Disease name in primary hypoadrenocorticism

Answer 1

Addison disease

Question 2

What hormones are lacking in hypoadrenocoriticism?

Answer 2

Adrenocortical hormones: lack of glucocorticoids, mineralocorticoids, or both.

Question 3

Hypoadrenocorticism vs Addison disease difference

Answer 3

Hypoadrenocorticism = adrenocortical insufficiency
Addison disease = Primary hypoadrenocorticism

Question 4

What does aldosterone do?

Answer 4

-Maintains water and electrolyte balance
-Conservation of Na+ and water
-Excretion of K+

Question 5

What three things will deficiency of aldosterone cause?

Answer 5

-Dehydration
-Hyponatremia
-Hyperkalemia

Question 6

Some clinical signs in case of aldosterone deficiency

Answer 6

-Weakness
-Polydipsia
-Polyurea
-Hypovolemic shock
-Cardiac arrhythmias

Question 7

Some functions of glucocorticoids

Answer 7

-Glucose metabolism and gluconeogenesis
-Immune system
-Inflammatory response
-Integrity of GI-mucosa
-Stress tolerance

Question 8

Some effects of glucocorticoid deficiency

Answer 8

-Waxing and waning clinical signs
-Impaired gluconeogenesis and glucogenolysis
-Stress and excercise intolerance
-GI disturbances
-Lethargy, weakness

Question 9

What is primary hypoadrenocorticism?

Answer 9

Destruction of adrenal glands (>90%)
–> deficiencies of mineralocorticoids and glucocorticoids

Question 10

Causes of primary hypoadrenocorticism:

Answer 10

-Immune-mediated destruction of adrenal cortex (most common; Addison disease)
-Iatrogenic: drug induced lysis
-Neoplasia, infection, infarction of adrenal glands

Question 11

What is secondary hypoadrenocorticism? Causes?

Answer 11

Decreased ACTH secretion.

-Iatrogenic: exogenous glucocorticoid administration –> inhibits release of ACTH
-Pituitary lesions

Question 12

What is “atypical” hypoadrenocorticism?

Answer 12

Deficiency of glucocorticoids (aldosterone) but mineralocorticods are normal. Symptoms are still similar but hyperkalemia and hyponatremia do not occur. Hypoglycemia might cause seizures.

Question 13

Which is more common: Cushing or Addison disease?

Answer 13

Cushing (hyperadrenocorticism) is significantly more common.

Question 14

Do cats have primary hypoadrenocorticism/Addison?

Answer 14

Very rarely, fewer than 40 cases described

If happens, it’s similar to canine Addison. Cats need double doses of glucocorticoids per kg of body weight compared to dogs.

Question 15

What are clinical signs in Addison?

Answer 15

Often not very specific. Symptoms might be related to stress (e.g. “stress colitis”)

-Recurrent episodes of gastroenteritis
-progressive loss of body condition
-failure to respond to stress
-lethargy
-anorexia
-GI-signs
-Polyuria
-Polydipsia
-Bradycardia
-Abdominal pain

Question 16

What happens in acute hypoadrenocorticism?

Answer 16

~30% of dogs go into hypovolemic shock

-Bradycardia, weak pulse, pale mucous membranes, increased CRT
-Vomiting and diarrhea
-Dehydration
-Abdominal pain

Question 17

Usually hypovolemic shock causes tachycardia but in acute hypoadrenocorticism we will see bradycardia. Why?

Answer 17

It’s called “relative bradycardia” and is caused by hyperkalemia - animal is not able to become tachycardic

Question 18

Hematology findings in hypoadrenocorticism?

Answer 18

Absence of stress leukogram!

-Eosinophilia
-Lymphocytosis
-Mild anemia that might be masked by hypvolemia

Question 19

Biochemistry findings in hypoadrenocorticism

Answer 19

-Hyponatremia
-Hyperkalemia
-Hypochloremia
(because of lack of aldosterone)

Also prerenal azotemia (hypoperfusion in kidneys)

Question 20

Urinalysis findings in hypoadrenocorticism

Answer 20

-Specific gravity usually low or might be isosthenuric. This is contradictory in dehydration.
-Might be difficult to differentiate from renal diseases

Question 21

What happens to the cortisol levels in ACTH-stimulation test in case of hypoadrenocorticism?

Answer 21

The levels do not rise, but stay low.

Question 22

Can ACTH-stimulation test differenciate between primary and secondary hypoadrenocorticism?

Answer 22

No

Question 23

What might give a false negative result in ACTH-stimulation test?

Answer 23

Cross reactions if patient has been given synthetic glucocorticoids

Question 24

Treatment of chronic hypoadrenocorticism?

Answer 24

Life-long supplementation of mineralocorticoids (e.g. fludrocortisone acetate) and glucocorticoids (e.g. prednisolone)

Question 25

Treatment of acute hypoadrenocorticism

Answer 25

-Aggressive fluid therapy
-Correction of electrolyte/acid-base disorders
-Correction of potential hypoglycemia

-Prednisolone or dexamethasone might be given (NB! might have an effect on ACTH test later)
-Mineralocorticoid replacement therapy is given

Question 26

What is Addison disease often called?

Answer 26

The great imitator because clinical signs are often vague. Clinician should keep Addison in mind as a possibility

Question 27

Prognosis in Addison?

Answer 27

Therapy is generally highly successful, often life-long, and results in an excellent longterm prognosis.

Question 28

Treatment of atypical hypoadrenocorticism?

Answer 28

Prednisolone

In anticipated stress dose must be increased 2-10 x

Some dogs might develop mineralocorticoid deficiency later

Question 29

Take-home message 1:

Answer 29

-Idiopathic bilateral atrophy of adrenal glands is the cause for most cases of primary hypoadrenocorticism (Addison disease)
-Absence of stress leukogram in a severely ill animal
-Three most important clinicopathological findings: hyponatremia, hyperkalemia, weak response to ACTH stimulation
-Prerenal azotemia and low urine specific gravity (difficult to differentiate from renal diseases)

Question 30

Take-home message 2

Answer 30

DOGS:
-Iatrogenic causes are the most common causes of secondary hypoadrenocorticism
-Hypovolemic shock –> collapse, A LIFE THREATENING CONDITION
-Functional test: ACTH-stimulation test

Question 31

Learning outcomes:

Answer 31

-Hypoadrenocorticism is an uncommon disease, but should be diagnosis as many cases as possible because prognosis is good if treated
-Hypoadrenocorticism is the great pretender and therefore easy to miss (variable and subtle presentation)
-Addisonian crises do occur and need aggressive management
-Client education is essential - need for ongoing monitoring and changes in therapy