Answers and Discussion
Case #7-- Addisonian Crisis
Answers and Discussions to the Questions:
- After examining the blood smear, what makes you think of an Addisonian
crisis?
The presence of lymphocytes and eosinophils is a sign of a lack of a stress
leukogram. Grisby had a history of vomiting and diarrhea which should initiate a
stress response and thereby the eosinophils and lymphocytes..
- Describe the abnormalites on the small animal biochemical profile which suggest
an Addisonian?
There is evidence of azotemia, a decreased sodium, increased potassium, and
decreased bicarbonate. The azotemia is hopefully prerenal (no urine was collected
prior to intravenous fluids!!). The decreased bicarbonate is likely due to a
metabolic acidosis. The sodium:potassium ratio in Grisby was 19. These are
classical findings in hypoadrenocorticism.
- Interpret the electrocardiogram in light of the
physical examination and clinical pathological results.
Two important electrocardiographic findings in Grisby are the extremely low
amplitude to the electrocardiogram and the single premature ventricular contraction.
The low amplitude is likely due to hypovolemia. Notice there are no
electrocardiographic signs of hyperkalemia in Grisby. The heart rate is 160/minute
and the P-wave is readily visualized.
Click here to review the electrocardiogram:
- Describe the intravenous fluid you would use in the initial resuscitation of
Grisby.
With Grisby's low sodium and elevate potassium levels, the fluid of choice is
0.9% Sodium Chloride.
- Select the corticosteroid you would use in the emergency treatment of Grisby.
Dexamethosone sodium phosphate is the corticosteroid of choice for the animal in
an Addisonian crisis. The reasons for this choice are related to the following
question.
Select the test you would use for confirmation of a diagnosis of
hypoadrenocorticism (Addison's disease).
An ACTH stimulation test is used to confirm hypoadrenocorticism. Because
you are not frequently prepared to run the ACTH test, dexamethasone sodium phosphate is
often used to provide glucocorticoids while not interfering with the ACTH stimulation
test.
The results from Grisby's ACTH stimulation were as follows:
Pre-Cortisol: < 1.0 ug/dl
Post-Cortisol: < 1.0 ug/dl
Post ACTH cortisol levels < 6.2 ug/dl indicates marginal response to ACTH and is
consistent with hypoadrenocorticism.
Follow-Up: "Grisby" was discharged from the Veterinary
Teaching Hospital after 3 days. His medications included prednisone and
desoxycorticosterone pivalate (DOCP). The owner was instructed to return to the
referring veterinarian's office for a recheck of the azotemia and electrolytes within one
week and a second recheck in 3 weeks. DOCA injections will be required about once
each month. Prednisone will be given daily.
Addisonian Crisis Pearls
- Hypoadrenocorticism is an emergency
- The diagnosis of an Addisonian crisis can be suggested based upon the lack of a stress
leukogram
- Biochemical profiles usually show a prerenal azotemia, an abnormal sodium:potassium
ratio, increased potassium levels, and evidence of a metabolic acidosis.
- Microcardia is common with dogs that are hypovolemic.
- Emergency treatment for hypoadrenocorticism involves first ruling out cardiac effects
from the hyperkalemia and then the prompt administration of 0.9% sodium chloride for shock
and maintenance fluid volumes.
- Dexamethasone sodium phosphate is given as a glucocorticoid in order to not interfere
with an ACTH stimulation test.
- The lack of cortisol response following the administration of ACTH confirms
hypoadrenocorticism.
|
Return to Introduction
Copyright 1999, Wayne E. Wingfield,
Colorado State University
This page was last edited: 04/08/99