Hypoadrenocorticism (Addison's Dz) Flashcards
What is Addison’s Dz?
the diminished secretion of one or more adrenocortical hormones
What is the underlying pathophysiology of primary Addison’s Dz?
- the problem is the adrenal gland itself
- suspected immune-mediated destruction of part of the adrenal gland
What do scientists think the immune-mediated destruction caused by?
infiltration of adrenal cortex with lymphocytes & plasmas cells that results in chronic inflammation and leads to tissue fibrosis and eventual destruction of adrenocortical cells
List two types of Addison’s
Typical
Atypical
What zona(s) are destroyed in typical Addison’s? What does that result in?
Glomerulosa (mineralocorticoid deficiency) &
Fasciculata (glucocorticoid deficiency)
What does Aldosterone deficiency look like
loss: sodium, chloride, water
retention: potassium
How does an aldosterone deficiency show up on bloodwork?
hyponatremia (low Na) Hypochloremia (low Cl) Hyperkalemia (high K) Dehydration as azotemia (increased BUN & CRE) Decreased SG
What zona(s) are destroyed in atypical Addison’s? What does that result in?
zona fasciculata only
result = decreased secretion of glucocorticoids
How does a glucocorticoid deficiency affect the body?
- decreased formation of new glucose molecules
- increased update of glucose by body’s cells
- inability of body to respond adequately to stress
How can you tell if a patient has typical vs atypical Addison’s?
Look at bloodwork; if low Na & Cl but high K, you’re looking at typical Addison’s which is deficient in 2 hormones
List the clinical signs of Addison’s
- Shock & dehydration
- Bradycardia
- Shivering, shaking, lethargy, weakness
- Polyuria
- V/D/Anorexia
Pathophysiology in Addison’s for: Shock & dehydration
result of aldosterone deficiency
- body can’t maintain proper sodium, potassium, and water concentrations
- water and sodium loss decrease blood volume and BP
result of glucocorticoid deficiency
-body can’t respond to decreased blood volume and BP
Pathophysiology in Addison’s for: bradycardia
secondary to presence of hyperkalemia
Pathophysiology in Addison’s for: shivering, shaking, lethargy, weakness
secondary to hyponatremia
Pathophysiology in Addison’s for: polyuria
excessive sodium loss into the urine alters concentration gradient within the kidneys and makes it difficult for kidneys to concentrate urine
Pathophysiology in Addison’s for: V/D/anorexia
secondary to glucocorticoid deficiency b/c glucocorticoids are necessary to maintain proper mucosal integrity of the intestines
Presentation of Addison’s animal in acute crisis
shock w/ evidence of dehydration, bradycardia, weak femoral pulse
Presentation of Addison’s animal with chronic intermittent illness
waxing and waning of shivering, shaking, lethargy, weakness, polyuria, V/D, anorexia
Presentation of Typical Addison’s
collapse, bradycardia, polyuria, polydipsia, GI signs, shivering or shaking, lethargy or depression
Presentation of Atypical Addison’s
vague signs of glucocorticoid deficiency, intermittent V/D +/- anorexia episodes; may be described as having a sensitive stomach; may have Hx of unexplained GI upset
What test is the gold standard for Addison’s?
ACTH Stimulation Test
What does ACTH stim test evaluate?
the ability of the adrenal glands to produce cortisol
How is the ACTH Stim. test done?
2 blood samples:
Sample 1 = baseline cortisol level for that patient
Sample 2 = drawn a specific time after injection of ACTH hormone
What will the results of an ACTH Stim test be for an Addison’s patient?
- low baseline cortisol lvl
- minimal to no response post ACTH administration
What are 2 considerations that are important to remember for ACTH stim testing?
- best to do at 8am because cortisol levels are most stable at that time
- reduce stress during testing procedure b/c cortisol lvls increase if pet is stressed
3 Meds that can be used for Addison’s patients
Fludrocortisone
Desoxycorticosterone
Pred/Prednisolone
Fludrocortisone
- type
- pros
- cons
- mineralocorticoid w/ some glucocorticoid activity; daily oral tablet
- Pro: easy to adjust dose, typically don’t need to add glucocorticoid
- Con: side effects of polyuria, polydipsia, incontinence
Desoxycorticosterone
- type
- pros
- cons
- mineralocorticoid IM/SQ injection q25-30 days
- Pros: excellent efficacy, easy to give, lack of side effects
- glucocorticoid therapy will need to be given
Pred/Prednisolone
- type
- reason to keep around
- glucocorticoid tablet
- keep extra stash in case of stressful event