Hypoadrenocorticism (Addison's Disease)

Question 1

What are the top 4 key tip-offs of Addison’s disease?

Answer 1

1. bradycardia in the face of cardiovascular collapse
2. severe dehydration with USG <1.030
3. Na:K ratio <27
4. episode brought on by stress - new household member, a move, medical procedure, etc.

Question 2

What is the diagnostic test of choice for Addison’s disease?

Answer 2

ACTH stimulation test

• post stiulation levels <2ug/dL

Question 3

What are the 3 critical therapies for Addison’s disease?

Answer 3

1. rapid infusion of fluids - 0.9% NaCl
2. treat severe hyperkalemia - calcium gluconate, Regular insulin, dextrose, bicarbonate
3. corticosteroids

Question 4

What is the most common cause of Addison’s disease? What 2 things does this lead to?

Answer 4

idiopathic adrenocortical atrophy

1. insuffient glucocorticoid levels for homeostatic function and glucose regulation
2. insufficient mineralocorticoid levels cause the inability to retain sodium and excrete potassium and hydrogen - hypotonic dehydration, hyperkalemia, metabolic acidosis

Question 5

What is atypical Addison’s disease?

Answer 5

deficiency of only glucocorticoids or mineralocorticoids, NOT both

Question 6

What animals are predisposed to developing Addison’s disease?

Answer 6

• middle-aged (3-7 y/o)
• female
• (black) Standard Poodles +/- Portuguese Water Dogs, Great Danes, Rottweilers, WHWT, Wheaton Terriers

Question 7

What are signs of acute and chronic Addison’s disease?

Answer 7

ACUTE - hypovolemic shock with weakness and vomiting (maybe hematemesis)

CHRONIC - worsening of signs with stressors, PU/PD, nonspecific (commonly mistaken for GI disease, renal disease, or pancreatitis)

Question 8

What are the 2 most common signs of Addison’s disease on blood chemistry? What else can be seen?

Answer 8

hyponatremia and hyperkalemia - Na:K <27

• hypochloremia
• hypercalcemia
• hypoglycemia
• pre-renal azotemia secondary to dehydration
• increased BUN due to GI bleeding
• hypoalbuminemia due to GI blood loss and PLE

Question 9

How will a urinalysis be affected by Addison’s disease?

Answer 9

low USG (<1.030)

Question 10

What is indicative of Addison’s disease on a CBC?

Answer 10

absence of a stress leukogram

Question 11

What changes on ECG are seen in Addisonian patients?

Answer 11

• bradycardia
• tall tented T waves
• diminished to absent P waves
• prolonged PR interval
• wide QRS complexes

Question 12

What are 3 possible findings on U/S in Addisonian patients?

Answer 12

1. megaesophagus
2. microcardia
3. small adrenal glands

Question 13

What can invalidate ACTH stimulation tests when diagnosing Addison’s disease?

Answer 13

any steroid other than Dexamethasone

Question 14

What are 3 parts to acute presentations of Addison’s disease?

Answer 14

1. restore blood volume - rapid administration of fluids like 0.9% NaCl (60-90 mL/kg shock dose, incremental 10-30 mL/kg until resuscitation to avoid rapid increases in sodium)
2. treat hyperkalemia - +/- cardioprotectant calcium gluconate
3. IV glucocorticoids - Dexamethasone SP

Question 15

What are 2 parts of lifetime maintenance required for Addisonian patients?

Answer 15

1. CORTICOSTEROIDS - Prednisone/Prednisolone starting at supraphysiologic dose (0.5 mg/kg/day) for one week and then taper down to maintenance (0.1-0.2 mg/kg/day)
2. MINERALOCORTICOIDS - Fludrocortisone (SID), injectable deoxycorticosterone pivilate (DOCP) every 3-4 weeks