RIVMA & Endocrine Diseases

While attending the Rhode Island Veterinary Medical Association conference in December I went to many interesting presentations, but the one presentation that was most relevant to me focused on endocrine diseases. The main endocrine diseases mentioned in the presentation were Addison’s disease, Cushing’s disease, and Hyperthyroidism in cats and Hypothyroidism in dogs. We see patients every day that suffer from these diseases, and we test them for diagnostic reasons as well as management reasons. Not only did the presenter go into detail about how to perform each test, he also explained why we are performing them and how to interpret the results.

The first disease mentioned was Addison’s disease, also known as hypoadrenocorticism. Addison’s disease is a result of inadequate glucocorticoid and mineralocorticoid production from the adrenal glands. The presenter recommended running bloodwork, urinalysis and an ACTH stimulation test. The ACTH stimulation test is the main test used to diagnose Addison’s disease. The steps to performing the test include drawing a baseline blood sample, injecting the patient with a synthetic form of ACTH, followed by drawing a sample an hour after giving the synthetic injection. A patient that has Addison’s disease will have low cortisol levels on both the pre and post blood samples drawn.

The second disease mentioned was Cushing’s disease, also known as hyperadrenocorticism. Cushing’s disease is a result of an increased level of cortisol in the body from either adrenal, pituitary, or hypothalamic dysfunction. There are several tests that can be performed to screen and diagnose for the disease. The tests used for confirming Cushing’s disease are the LDDST and HDDST test. The LDDST, or Low-dose dexamethasone suppression test, can be used to confirm a tumor on the pituitary or adrenal gland. The steps to perform the LDDST test include taking a baseline blood sample, giving an injection of dexamethasone, then drawing a blood sample four and eight hours after the injection. The results can be interpreted in multiple ways: no suppression at four and eight hours confirms Cushing’s disease; suppression at four hours and peak at eight hours confirms a pituitary gland tumor; and no suppression with cortisol levels less than 50% of baseline it is most likely a pituitary gland tumor. If the LDDST is inconclusive then an HDDST should be performed. An HDDST, or high-dose dexamethasone suppression test, is run to force the suppression of cortisol to confirm a pituitary gland tumor.

The last diseases discussed were hyperthyroidism in cats and hypothyroidism in dogs. Both diseases are results of an abnormally functioning thyroid gland. The recommended diagnostic tests should be full bloodwork, urinalysis, and a total T4. An elevated level of total T4 is diagnostic for hyperthyroidism in cats. On the other hand, hypothyroidism in dogs often results from a lack of secretions of T4 from the thyroid gland. A few tests are run to diagnose hypothyroidism such a complete bloodwork, a urinalysis, a total T4, free T4, and TSH levels. The total T4 will be low in most patients and can be used for a screening test.

I thoroughly enjoyed the entire conference, but this presentation was quite memorable. I appreciated discussions, in which we learned about common diseases seen regularly and how the patient’s body can malfunction. Moreover, learning about why we are performing specific tests and how to read the results were the most important aspects of the presentation. As a technician, understanding how to perform a test is important, but learning why we are performing these tests is even more essential. With the knowledge I learned at the conference, it will become much easier for me to speak to owners when they are dropping off and picking up their beloved pets. The more confidence I can have, the more confidence the owners will have in me as well, and this can be done through education.