Searching for Addison’s Disease

A severely emaciated lost dog is diagnosed with Addison’s Disease after presenting with unexplained hypoglycemia, vague GI signs, significant dehydration and normal resting cortisol that was finally diagnosed as true Addisonian on stimulation test.

By Jennifer Sergeeff, DVM,
Diplomate American College of Veterinary Internal Medicine (Small Animal Internal Medicine)

Wong Ga Truong presented to the Internal Medicine Service on 9/9 for vomiting, anorexia, and dehydration.

Wong Ga was missing for the past year. She came home about 6 weeks ago. Owner reports she was thin, had sores all over her body. Placed on anti-fungal shampoo. She was walking and eating normally. Then this week, she has had zero appetite, lethargic, and not drinking for 2 days, and vomited 4 times yesterday. Lethargy worsened today to not walking.

On no chronic oral medications. No known toxins in past 6 weeks since been home.

Initial Investigation

PHYSICAL EXAM

8-10% dehydrated. Lateral recumbency. Scruffy coat with crusted scabs over back. Generalized muscle atrophy with BCS 3/9. Depressed mentation.

Diagnostics:

• Blood pressure: not readable at admission. 80 mm Hg (after 1 hr fluids).
• In-house bloodwork:
  • CBC: HCT=59.4%. WBC normal
  • Chem: Glu=38; BUN=60, PO4=10.3, Na=140, K=5.4 (normal),
• SNAP cPL: Normal
• Radiographs: Hypovolemic heart. Small liver. Empty stomach. Constipated.
• 2 view thorax/abdomen: Heart and vessels are small consistent with dehydration. No pleural disease.
• Abdominal ultrasound: Imaging Impressions: 1) Small liver 2) Hyperechoic focal lymph node in region of colon 3) Mild sludge in gall bladder—consistent with not eating.
• UA: SpG=1.051, 3+ protein, no growth on culture
• B12/folate (looking for malabsorption due to emaciated state): Normal
• Resting cortisol: 2.3 (in normal range)
• Fecal O/P/G: All negative
• Bile acids: Pre=1.7, Post=29.8 9( slightly elevated)

Initial Problem List

1. Dehydration
2. Anorexia/vomiting x 48 hours: r/o extra-GI (renal, hepatic, pancreatic, cancer, endocrine, other) vs intra-GI (IBD, SIBO, infection, cancer, parasites, partial or full obstruction, other).
3. Poor body condition with muscle loss: likely chronic malnutrition while missing, but cannot r/o extra/intra GI causes as above including malabsorption disease in intestines
4. Skin lesions: r/o FAD, infection, fungal, other chronic disease
5. Dental disease
6. Hypoglycemia: r/o Addisons, liver failure, sepsis, use, malnutrition, xylitol toxicity, cancer, other
7. Constipation

Day 2 testing

After 18 hours on IV fluids and rehydrated, rechecked electrolytes:

• ISTAT 8: PCV/TS: 46%/6.0. Na=130 (low), K=5.9, Glu=83.
  Due to persistent hypoglycemia and now low Na, do full ACTH stimulation test for adrenal function
• ACTH STIMULATION TEST: Pre=0.9; Post-0.8 (Addison’s disease)

Diagnosis

Addison’s disease

The Challenge

The challenge in this case was multi-factorial. First, the pet had been missing for over a year, so we did not have adequate history. Anything could have happened in that year, so there were a lot of potential variables. Second, Addison’s was on the list of potentials, but the resting cortisol level was normal, so other possibilities were then investigated. Finally, the “classic” electrolyte changes were not there during hospitalization (never combination of low Na and high K), but the persistent unexplained hypoglycemia without other known causation, kept bringing us back to Addison’s.

Treatment

Rehydration over 18 hours and added dextrose to support hypoglycemia. Gave GI protectants (Pepcid and Cerenia) since vomiting. Gave Vitamin B12 since poor condition, and Unasyn pending urine cultures. Clipped/cleaned/topically treated all open sores on back.
Day2: Started prednisone 0.4 mg/kg/day and DOCP 2 mg/kg IM. Sent home on Prednisone 0.4 mg/kg/day x 5 days then lowered to 0.2 mg/kg/day and DOCP 2 mg/kg IM q 30 days.

Outcome

Patient did very well. Starting eating on day 2, and by day 3 (24 hours after steroids started) the low blood sugar normalized and was able to be weaned off fluids and sent home on oral medications. Recheck at 30 days showed normal electrolytes and blood sugar and patient has gained 1.01kg of body weight.

Discussion

This case is interesting on two fronts. First, it shows that a single resting cortisol value does not r/o Addison’s disease. As much as recent papers suggest a single cortisol value has high sensitivity, this case shows there are false negatives. In retrospect, on day 1 blood work the “normal” sodium (140) on presentation in the face of 8-10% clinical dehydration might have been an early clue that the sodium level was being suppressed (as we would expect hyPERnatremia in a severely dehydrated patient). A normal sodium in the face of significant dehydration can indicate relative hypoaldosteronism. This of course is hindsight in light of the final diagnosis. Secondly this case presentation shows the importance of monitoring trends of blood work (rechecking electrolytes once deemed rehydrated). Without this, the development of hyponatremia likely would have been missed, which was the key factor in submitting a full ACTH stimulation test.

Lack of cortisol production causes GI upset, lethargy, weakness, low blood glucose, and contributes to low blood pressure. It can even cause stiff/sore muscles. Lack of aldosterone causes electrolyte and body fluid disturbances, usually including high potassium, low sodium, and excessively acidic blood pH.

Middle -aged female spayed dog are the most commonly affected, but it can occur in any breed, age, or sex of dog. Signs of Addison’s may be extremely vague and even wax and wane. Signs can include anorexia, lethargy, vomiting, diarrhea, weakness, shaking, reluctance to walk, even collapse. These dogs often respond well to IV fluids and other supportive care in the hospital, but relapse after they are sent home if the condition is not diagnosed and treated specifically.
The ACTH stimulation test looks at the change in cortisol levels in response to an injection of pituitary hormone (ACTH). All dogs with Addison’s will have minimal increase in cortisol after the ACTH injection. Sometimes it is also relevant to look at changes in aldosterone levels in response to the ACTH.
Addison’s can be straightforward to manage, as long as you owners are vigilant and remain mindful of medications. Most Addisonian dogs thrive with proper care.

Picture of Wong Ga 5 days after discharge. (still skinny)