hypoadrenocorticotism addison Flashcards
how difficult is it to dx addison (hypo)
easy to dx and tx
primary vs secondary hypoadrenocotism
-
Primary hypoadrenocorticism
- More than 95% of cases
- Plasma ACTH high
- Mineralocorticoid & glucocorticoid-dependent (most common)
- Glucocorticoid-dependent (less common)
-
Secondary hypoadrenocorticism
- Glucocorticoid deficiency only
- Less than 5% of cases
- Plasma ACTH low
- Exogenous steroid administration (more common)
- Hypopituitarism (less common)
discuss primary hypoadrenocortoctism
-
Mineralocorticoid and glucocorticoid dependent
- More common
- Idiopathic destruction
- Mitotane or trilostane treatment
- Bilateral adrenalectomy
-
Glucocorticoid dependent (“atypical”)
- Less common (5-25% of cases)
how is atypical hypoadrenocorticotism different
- Similar to “classical” but serum electrolytes are normal
- May remain glucocorticoid-dependent for months to years or progress to mineralocorticoid-dependence
- Difficult to diagnose because signs are vague
signalment for hypocortticotism
- Approximately 75% are < 7 years at diagnosis (75%)
- Average age -4 years
- Approximately 70% are females
- Any breed or mixed breed
- but tends to be a large breed dog dz
history for addison dog
- Illness for a few days to several months
- Chronic disorder that waxes and wanes (25-40%)
- Acute collapse (10%)
- History of previous tx and favorable response to fluids and/or glucocorticoids (25-35%)
what do u see on PE for addison dog
- IT MAY BE NORMAL
- Lethargy (85%)
- Thin body condition (80%)
- Weakness (65-75%)
- Dehydration (40-45%)
- Signs of shock (25-35%)
- Bradycardia (20%)
- Related to hyperkalemia
- Especially in a dog in shock -helpful clue!
LESS COMMON FINDINGD FOR ADDISON DOG
- Hypothermia (15-35%)
- GI ulceration and melena (15%)
- Glucocorticoids needed for maintenance of normal GI mucosa
- Lack of glucocorticoids / poor tissue perfusion
- Abdominal tenderness (7-10%)
CBC FINDINGS FOR ADDISON DOG
- Anemia (25-35%)
- Typically non-regenerative
- Anemia of chronic disease
- GI blood loss (may be semi-regenerative)
- May be masked by dehydration
-
Leukogram
- Absolute eosinophilia (10-20%)
- Absolute lymphocytosis (10-15%)
- Normal numbers of eosinophils and lymphocytes in sick dog RED FLAG!
- Glucocorticoids: eosinopenia and lymphopenia (stress leukogram)
- Plasma proteins may be increased due to dehydration
CHEMISTRY PROFILE FOR ADDISON DOG
- K AND NA RATIOS
- BUN
- P
- ACID BASE STATUS
- Sodium and potassium abnormalities
- Hyperkalemia (90-95%)
- Hyponatremia (80-85%)
- Na:K ratio < 27:1 (90-95%)
- Hypochloremia (40%)
- Azotemia
- Increased BUN (90%), increased creatinine (60-65%)
- IF U GIVE FLUIDS THEY GET PRERENAL AZOTEMIA
- Increased BUN (90%), increased creatinine (60-65%)
- Hyperphosphatemia (65%)
- Metabolic acidosis (40-45%)
MOST IMPORTANT CHEMISTRY FINDINGS FOR ADDISONS
- Hypoglycemia (15-20%) *
- Hypocholesterolemia (15%)*
- Hypoalbuminemia
- *Possibly more common in “atypical” hypoadrenocorticism
WHAT DO U FIND IN URINALYSIS ON DOGS WITH ADDISON
- Low urine specific gravity (60% have USG < 1.030)
- Renal medullary washout of solute
- May cause confusion with acute renal failure
- Renal function returns to normal after rehydration and re-establishment of normal renal medullary solute concentration
WHAT DO WE SEE ON RADS FOR ADDISON
- NT ALWAYS INDICATED
- Microcardia (hypovolemia)
- Megaesophagus (< 1%)
THE VALUE OF DOING RESTING CORTISOL IN DX ADDISON
- Resting plasma cortisol may be useful to rule out dz
- Sensitivity 100% and specificity 98% if ≤ 1.0 μg/dL
- Sensitivity 100% and specificity 78% if ≤ 2.0 μg/dL
- NEVER use resting plasma cortisol to try and rule it in
WHICH TEST SHOULD BE USED TO CONFIRM DX FOR ADDISON
- ACTH STIMULATION TEST
- Should be used confirm diagnosis
- Plasma cortisol determined before and 1 hour after ACTH administration
- Best to perform before administering glucocorticoids that may interfere with test results
- Dexamethasone does not cross react with cortisol on RIA and can be given if necessary
ACTH Stimulation Test Interpretation FOR CLASSICAL ADDISON
Both pre-and post-ACTH cortisols < 2.0 μg/dl in nearly 100% of cases (most < 1.0 μg/dl )
ACTH Stimulation Test Interpretation FOR ATYPICAL ADDISON
Low resting cortisol (≤ 2.0 μg/dl) with little response to ACTH (≤ 4.0 μg/dl)
ACTH Stimulation Test Interpretation FOR Secondary hypoadrenocorticism (hypopituitarism)
Low resting cortisol (≤ 2.0 μg/dl) with little or no response to ACTH (≤ 3.0 μg/dl)
EMERGENCY TX FOR ADDISON
- Correct hypovolemia and restore tissue perfusion
- Correct electrolyte and acid base disturbances
- Replace missing mineralocorticoids
- Replace missing glucocorticoids
FOR ADDISON TX, Fluids and parenteral medications continued until:
- BUN and serum creatinine return to normal
- Serum electrolytes and acid base balance return to normal
- Animal begins to eat and drink without vomiting
drugs for long term maintainance for addisonians
- Desoxycorticosterone pivalate (DOCP)
- no glucocorticoids . therefore give with steroids
- Fludrocortisone (Florinef®)
AVDAVANTAGES OF Fludrocortisone (Florinef®) AS A SUBSITUTE FOR ADDISON TX
IT HAS BOTH mineralocorticoid and glucocorticoid effects
DISAD. FOR Fludrocortisone
- Some dogs respond poorly (poor GI absorption?)
- Some dogs develop adverse effects due to excessive glucocorticoid activity at dosages required to control serum electrolyte concentrations (e.g. PU, PD, polyphagia, weight gain, hair loss)
- In some dogs, glucocorticoid effect avoids need for supplemental prednisone
TX FOR ATYPICAL ADDISON
- Dogs with secondary hypoadrenocorticism or “atypical” (glucocorticoid dependent) primary hypoadrenocorticism
- Require only glucocorticoid supplementation
- Dogs with “atypical” (glucocorticoid dependent) primary hypoadrenocorticism may go on to also become mineralocorticoid-dependent (vigilance is warranted)
