Exam 4 - Hypoadrenocorticism

Question 1

what is the general cause behind primary hypoadrenocorticism?

Answer 1

destruction/infiltration of adrenal cortices

Question 2

what is the most common pathogenesis of primary hypoadrenocorticism?

Answer 2

immune-mediated destruction

Question 3

what is ‘classic’ hypoadrenocorticism?

Answer 3

mineralocorticoid & glucocorticoid deficiency

Question 4

what is ‘atypical’ hypoadrenocorticism?

Answer 4

some dogs with primary hypoadrenocorticism that only suffer from a lack of cortisol - > 25% of cases

can be from lack of acth production

Question 5

why does secondary hypoadrenocorticism occur? is it common?

Answer 5

lack of ACTH production - nope

signs reflect lack of cortisol because secretion is entirely dependent on acth, with aldosterone production unaffected

Question 6

why may we see iatrogenic hypoadrenocorticism?

Answer 6

may be the result of abrupt withdrawal of exogenous steroids - signs occur due to lack of cortisol

may occur with therapy for cushings with trilostane or mitotane - signs are due to lack of cortisol +/- aldosterone

Question 7

what are some examples of metabolic processes that are affected by cortisol?

Answer 7

gluconeogenesis

immunologic function

hepatic synthesis of albumin

effective hematopoiesis

Question 8

what are some general signs seen that are attributed to a lack of cortisol?

Answer 8

anorexia, vomiting, diarrhea

lethargy & depression

weight loss

abdominal pain

signs are exacerbated by stressors

Question 9

what is aldosterone essential for in the body?

Answer 9

end point of the RAAS system - essential for sodium retention & adequate extracellular fluid volume & regulates potassium by promoting excretion by kidneys (save sodium & pee potassium)

Question 10

what are some general signs attributed to aldosterone deficiency?

Answer 10

weakness, hypotension

dehydration & pre-renal azotemia

cardiac consequences of hyperkalemia - bradycardia, irregular beats, & sinus arrest

Question 11

what is the common signalment of dogs affected by hypoadrenocorticism?

Answer 11

young (4-6 years old), female (70% of cases)

portuguese water dog, standard poodles, & westies

Question 12

T/F: even though there is a poster child for addison’s. a dog is never too young, too old, too big, or too small for the disease

Answer 12

true

Question 13

T/F: most dogs with addison’s are examined at least 3 times before a diagnosis is made

Answer 13

true

Question 14

what are some chief complaints that are seen in addisonian patients?

Answer 14

often vague - ADR

commonly suggests gi disease - vomiting, diarrhea, anorexia, bloody vomit & diarrhea are common

unlocalized abdominal pain

regurgitation

seizures & collapse

Question 15

T/F: clinical signs of addison’s may be triggered by a stressful event such as boarding, travel, house guests, & surgical procedures

Answer 15

true

Question 16

lack of __________ in addisonian patients will cause the most dramatic clinical signs such as weakness, severe dehydration, bradycardia (inappropriate in a dehydrated patient - should be tachycardic), abdominal pain, & hypothermia

Answer 16

aldosterone

Question 17

T/F: addison’s should make your differential list if you have a sick dog with > 500 eosinophils/ul

Answer 17

true

Question 18

what lab abnormalities are commonly seen on cbc from an addison’s patient?

Answer 18

anemia is common - gi bleeding from cortisol deficiency, decreased production from cortisol deficiency

polycythemia - from dehydration

lack of a stress leukogram!!!!! eosinophilia is a classic marker

Question 19

why are your serum electrolytes all over the place in addisonian patients? what changes may you see first?

Answer 19

they are profoundly affected by the lack of aldosterone!!!!

hyponatremia may precede hyperkalemia

Question 20

what ratio of sodium:potassium may clue you into a diagnosis of addison’s?

Answer 20

<1:27 very suggestive

Question 21

what electrolyte abnormalities are commonly seen on biochemistry panel from an addison’s patient?

Answer 21

sodium - low due to aldosterone deficiency

potassium - high due to aldosterone deficiency

phosphate - high due to decreased renal blood flow

chloride - low due to gi & urinary losses

calcium - elevated total calcium due to decreased renal blood flow & hyponatremia

Question 22

what changes are seen on a chemistry panel due to lack of cortisol in addisonian patients?

Answer 22

hypoglycemia, hypocholesterolemia, hypoalbuminemia, changes in liver enzymes (ALT, AST mildly increased), ALP may be strangely low, & increased BUN due to gi hemorrhage

Question 23

what abnormalities are commonly seen on biochemistry panel from an addison’s patient?

Answer 23

BUN - elevated due to dehydrated and/or gi hemorrhage

creatinine - elevated due to dehydration

albumin - elevated due to dehydration or decreased due to gi blood loss

glucose - +/- low due to impaired gluconeogenesis

cholesterol - +/- low due to impaired hepatic & gi function

Question 24

what would you expect to see on urine analysis for an addisonian patient? why?

Answer 24

urine specific gravity < 1.020 - lack of aldosterone impacts urine concentrating ability

casts may be noted if severe dehydration has caused tubular damage

Question 25

what may be seen on thoracic radiographs of an addisonian patient?

Answer 25

microcardia pulmonary hypoperfusion megaesophagus

Question 26

what may be seen on abdominal ultrasound of an addisonian patient?

Answer 26

small adrenal glands in most cases (left cranial pole < 3.7 mm) very rare, but may see infiltrated & enlarged glands

Question 27

what are six examples of when you should list hypoadrenocorticism as a differential for a sick dog?

Answer 27

1. patient has waxing/waning non-specific illness with anorexia & lethargy, with eosinophilia noted, if they improve with fluids, or if they improve with steroids 2. episodes of diseases that seem to be triggered by stressful events 3. any patient with gi disease - may be acute, chronic, severe, or signs of substantial gi hemorrhage 4. any patient with azotemia 5. any patient with hyponatremia/hyperkalemia 6. any patient with hypoglycemia

Question 28

how is baseline cortisol used to establish a diagnosis of addison's?

Answer 28

baseline cortisol < 2 ug/dl is highly suggestive - in house assays are fast but not all options are reliable, so use a send out test to verify

Question 29

why do you need to be careful if using a baseline cortisol measurement to diagnose addison's in a patient that has recently been on prednisone?

Answer 29

cortisol assays cross react with prednisone! may not get correct results

Question 30

how is an ACTH stimulation test used to diagnose addison's disease?

Answer 30

ideally performed prior to giving any steroids, but dexamethasone is okay because it's not detected by cortisol assays same procedure as covered for cushings

Question 31

how is an ACTH stim test interpreted for diagnosing addison's?

Answer 31

flat line result confirms it - cortisol is usually below detection limit both pre & post post <3 ug/dl is diagnostic for HOC, 3-5 ug/dl is suspicious

Question 32

T/F: a single baseline cortisol concentration > 2 ug/dl rules out addison's disease

Question 33

what test is required to differentiate between primary & secondary hypoadrenocorticism in dogs with normal electrolytes?

Answer 33

endogenous acth levels

Question 34

will a cortisol to acth ratio identify a dog with secondary hypoadrenocorticism? how is it used?

Answer 34

nope! in house platforms used to measure acth patient side - dogs with primary HOC have very low cortisol & very high acth

Question 35

T/F: a patient in an addisonian crisis may die of hyperkalemia within minutes of presentation

Answer 35

true

Question 36

what is the purpose of using fluid therapy for a patient in an addisonian crisis?

Answer 36

used to improve renal perfusion & will dilute serum potassium

Question 37

T/F: in an addisonian crisis, any replacement crystalloid is okay to use

Answer 37

true

Question 38

what is the ideal fluid choice to use for a patient in an addisonian crisis? what other electrolyte are you watching when you start this therapy?

Answer 38

0.9% NaCl (potassium free) unless sodium is <130 mmol/L - if so, need to use LRS or create a fluid with [Na] within 10 mmol/l of the patient chloride - can rise with NaCl

Question 39

what is the purpose of adding dextrose to fluid therapy for a patient in addisonian crisis? how is this achieved?

Answer 39

addresses hypoglycemia & facilitates the shift of potassium into the cells add 50 ml of 50% dextrose to 1 liter of fluid to get a 2.5% solution

Question 40

how can dextrose be used to manage hyperkalemia in a patient in an addisonian crisis?

Answer 40

0.25 ml/kg of 50% dextrose IV - dilute if not going fast with fluids & then supply dextrose in fluid bag at 2.5%

Question 41

how can beta agonists be used to manage hyperkalemia in a patient in an addisonian crisis?

Answer 41

terbutaline at 0.01 mg/kg IV/IM/SQ albuterol by inhaler

Question 42

how can calcium gluconate be used to manage hyperkalemia in a patient in an addisonian crisis?

Answer 42

stabilizes the heart muscle, but does not decrease serum potassium levels!!! 0.4-1.0 ml/kg over 20 minutes

Question 43

how can regular insulin be used to manage hyperkalemia in a patient in an addisonian crisis?

Answer 43

moves potassium into cells, but you must provide dextrose in fluids to prevent hypoglycemia risk of hypoglycemia without careful monitoring - regular insulin is your last choice to use!!!! 0.05 U/kg IV

Question 44

what is fludocortisone? what is its purpose?

Answer 44

oral drug that works as an aldosterone replacement - works faster than DOCP but is less reliable we use it as a bridge before giving DOCP as we wait for confirmation of diagnosis

Question 45

what is DOCP?

Answer 45

desoxycorticosterone pivalate (percorten-v, zycortal) potent mineralocorticoid - need to decrease book dose by 25% in larger dogs

Question 46

T/F: after an addisonian crisis, most patients are better within 12-24 hours & can generally be switched to oral medication and be weaned off fluids within 24 hours

Answer 46

true

Question 47

how is glucocorticoid replacement therapy done for addisonian patients after a crisis?

Answer 47

start prednisone at a supra-physiologic dose (0.5-1.0 mg/kg/day) because they are under tremendous stress from their illness taper them down to the lowest effective dose over 4 weeks - approximately physiologic dose (0.1 mg/kg/day) may need to increase if a stressful event is anticipated or occurs need to decrease dose if pu/pd occurs

Question 48

T/F: if you ever have an addisonian cat, you need to use prednisolone at a higher physiologic dose (0.3 mg/kg/day)

Answer 48

true

Question 49

when do you need to start mineralocorticoid replacement in an addisonian patient?

Answer 49

only necessary if serum electrolytes are abnormal!!! DOCP is drug of choice

Question 50

how is DOCP given to patients with addison's? what is the recheck schedule used? why?

Answer 50

SQ every 25 days, 2.2 mg/kg, but lower in giant breeds (1.1 mg/kg) check electrolytes day 12 & 25 - verifies adequate dose (day 12) & duration (day 25) check lab work every 3-6 months when stable

Question 51

what client information is necessary for owners with addison's dogs?

Answer 51

life long therapy is required normal life span is expected need to increase prednisone at times of stress