As far as bloodwork goes, there is a little difference between primary Addison's and secondary Addison's. Very simply put, in primary Addison's the adrenals stop working. In secondary Addison's the pituitary gland (or hypothalamus) fails to tell the adrenals to produce properly.
Primary Addisonians need to replace the mineralocorticoid that the adrenals aren't producing--either by daily pills (Florinef) or monthly DOCP shots (Percorten-V). And this regulates the electrolytes--the sodium and potassium levels in the blood. In addition, many of these dogs also need regular glucocorticoid replacement (usually prednisone or hydrocortisone). Secondary Addison's frequently only need glucocorticoid replacement.
For the dogs with primary Addison's, one of the main problems is their inability to conserve sodium and excrete excess potassium. As a result, to check that the dose of Florinef or DOCP is correct, one of the first things that's looked for in the blood tests is that the sodium level is above the
minimum of about 140 and that the potassium level is below the maximum of about 5.6. The "normal" numbers vary a little bit from lab to lab.
Next, these imbalances of sodium and potassium affect the kidney values--the Blood Urea Nitrogen (BUN) and creatinine. This is why Addison's is frequently misdiagnosed as kidney failure. Fortunately once treatment is started, these values go back into the normal range.
Then there are the Alk. Phosphatase and ALT. These are liver enzymes that sometimes leak into the bloodstream and this can be the result of long-term steroid use. So elevated liver enzymes is sometimes a sign that the prednisone dose is a little too high. We try to give our dogs just the amount of prednisone or hydrocortisone (or Dexamethansone) that is needed to replace
what the adrenals aren't producing, which is different from the "therapeutic" dose that's normally prescribed.
Obviously, the other values also have something to tell the vet--the chloride, the glucose, the bilirubin, the phosphorus. But the values I listed above are the ones that my vet tracks most intently when judging the effectiveness of our treatment of Cosette's Addison's.
But, as I mentioned, if your dog has secondary Addison's, you shouldn't have to worry about the sodium and potassium numbers like the rest of us. (Aren't you lucky!). My human endocrinologist told me that people with secondary
Addison's aren't in danger of dying from the undiagnosed disease--but they sometimes just walk around for years feeling really lousy until they are diagnosed.
The thing about Addison's is that our dogs are really very sick when they're diagnosed. But the great thing is that once started on medication, these values come back into line pretty well.
Hope this helps,
Mary Ann and Cosette (standard poodle)
Canine Addison's Disease FAQ