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INTERNAL MEDICINE & CRITICAL CARE CLIENT FORMS
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Hypoadrenocorticism
(Addison's) was first discovered in 1855 in human patients by a physician
named Thomas Addison for whom the disease is also named. It refers to a
condition where there is insufficient production of specific hormones from
the adrenal gland.
What are adrenal glands?
The adrenal
glands are 2 small glands that sit above each kidney. They are responsible
for secreting various hormones. There are 2 classes of hormones that are
specifically affected in patients that have Addison’s – mineralocorticoids
and glucocorticoids (cortisol). Some patients have deficiencies in both
hormones while others may only be glucocorticoid deficient. Glucocorticoids
such as cortisol are critical in maintaining normal sugar, fat and protein
metabolism in the body. They are also important in maintaining normal
physiologic function in times of stress. Release of glucocorticoids from
the adrenal glands is controlled by a hormone called adrenocorticotropic
hormone (ACTH) from the pituitary gland.Mineralocorticoids are the hormones responsible for maintaining normal
electrolyte and water balance in the body. Both of these
hormones play an important role in helping the body adapt to stressful
situations and without them the body fails to function correctly.
What are the signs of Addison’s disease?
Unfortunately the
signs of hypoadrenocorticism can be very vague. They can range from
malaise, lethargy and poor appetite to collapse and shock. The variability
of symptoms can mimic a wide range of other illnesses such as kidney
disease, neurologic diseases or gastrointestinal disease.
How is Addison’s diagnosed? In addition to
clinical signs and history, there may be clues in the routine blood tests
that can sometimes be suggestive of this disease. Some of the more salient
changes are low blood sugar, high calcium, low sodium and elevated
potassium levels. Patients with Addison’s don’t necessarily have to have
all of these changes and the abnormalities may be subtle. If your
veterinarian suspects Addison’s disease based on your pets signs or lab
data, the most definitive test is an ACTH stimulation test. For this test
a blood sample is drawn, a synthetic version of the adrenocorticotropic
hormone secreted from the pituitary gland is given, and a second blood
sample is drawn an hour later. These blood samples are then sent to a lab
to measure cortisol (steroid) levels. In normal dogs, there should be a
rise in the cortisol level between the first and second sample. In
Addisonian dogs, the cortisol level starts low and stays low despite the
ACTH.
How is Addison’s disease treated?
The main goal of
therapy in these patients is providing them with a source of the hormones
they are deficient in. Fludrocortisone (Florinef)
is one of the drugs that your veterinarian may use. It is primarily a
mineralocorticoid but also has some glucocorticoid activity. It comes in
pill form and must be given daily. Desoxycortisone
pivalate (DOCP) is an injectable mineralocorticoid that is given
approximately every 25 days. Because this medication has no glucocorticoid
activity however, daily cortisol supplementation such as prednisone will
also be needed. Some dogs respond better to DOCP while others do well with
Florinef so you and your veterinarian will decide which is the best
medication for your pet. Since patients
with Addison’s cannot produce enough cortisol on their own, it is
necessary to provide extra supplementation during stressful events such as
boarding, grooming, travel, etc. Your veterinarian will give you
guidelines about this as well.
What about monitoring and follow-up care?
Once your pet has
been diagnosed with Addison’s disease it will be important to see your
veterinarian periodically to evaluate the electrolyte levels and kidney
function. Keeping an eye on how they are doing at home is also important –
are they eating well? any vomiting or diarrhea? Lethargy? Any sign of
illness should prompt a phone call or a visit to your veterinarian. In the
event that your pet is feeling ill and may be experiencing a relapse of
their Addison’s disease, your veterinarian may also instruct you to give
an extra dose of prednisone when you start to see any problems.
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