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News Dr Peterson just returned from GEMFE's Third Congress of Feline Medicine in Seville, Spain, where he lectured on a number of topics in feline en
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Dr Peterson just returned from GEMFE's Third Congress of Feline Medicine in Seville, Spain, where he lectured on a number of topics in feline endocrine disease.
Seville is the city in Spain where Columbus' three ships were built, and his point of departure for his trip across the Atlantic to the "new world." Dr Peterson was lucky enough to get to visit the room where Columbus met with Queen Isabella to plan the expedition, as well as the cathedral which houses his tomb. |
Dr. Peterson is serving as the Endocrinology Section Editor for the next edition of August's Consultations in Feline Internal Medicine, published by Elsevier and due out in about a year.
Topics for his section include management of idiopathic hypercalcemia, the difficult diabetic, clinical remission and survival in diabetes, and use of thyroid hormone supplementation to preserve kidney function in cats treated for hyperthyroidism. |
Connecticut Veterinary Medical Association Annual Meeting & Convention
Hartford, Connecticut, April 2, 2014
Topics:
• Diagnosis and treatment of canine and feline hypothyroidism
• Feline hyperthyroid Update: What’s New?
• Update in diagnosis and treatment of Cushing’s disease in dogs
• Insulin and diet choices for the diabetic: What protocols work best? |
CE and the City 2014
New York, New York, April 26, 2014
Topic:
• Update in Hyperthyroidism |
2014 ACVIM Forum
Nashville, Tennessee, June 4 - 7, 2014
Topics:
• Advances in feline hyperthyroidism: A strategy to slow progression of concurrent CKD |
This Month's Top Post on the Insights Into Veterinary Endocrinology Blog |
I have a quick question about a "problem" case, a 9-year old M/C DSH. This cat has lost about 3 pounds over the last year, but weighed 22 pounds last year so the owner has been trying hard to get the cat to lose weight.
The cat came in for his recheck last week. His physical examination was normal and we ran a routine blood panel (CBC, serum chemistry panel, and total T4). His serum T4 was high-normal at 3.7 µg/dl (reference range, 0.8-4.0 µg/dl). I then added on a free T4 by dialysis, which came back as slightly high at 54 pmol/L (10-50 pmol/L). Looking back in his records, his free T4 concentrations were also slightly high when checked a year ago (58 pmol/L).
This cat is not clinical at all otherwise for hyperthyroidism. He has strange seizure-like episodes, about once every 3 months, but these have been happening since he was a young cat. There has been no change in these episodes.
My gut is telling me that because this cat is not clinical and his thyroid values have remained stable over the last year, we probably should not treat hyperthyroidism at this time. However, I wanted to get your opinion and see if you think that this cat is indeed hyperthyroid, and if so, if he may be a candidate for I-131 at this time. |
My Response:
In our studies, we have found that up to 30% of cats that present like this (asymptomatic, high-normal T4, slightly high free T4 concentration) will be normal when evaluated by thyroid scintigraphy (1-3). So basically, this cat certainly could be in the preclincal stages of becoming hyperthyroid, but it's also very possible that the free T4 is falsely high and he is euthyroid.
Determination of free T4 is far from being a perfect test, and a diagnosis of hyperthyroidism should NEVER be based on the finding of a high free T4 alone (1,2,4). This is especially true in a cat like this one, that presents without a palpable thyroid nodule or clinical features of thyroid disease.
So you and the owners have 2 options at this time:
1. Do a thyroid scan (scintigraphy) to better define the cat's thyroid function (1-3,5,6). If the thyroid lobes are of normal size and display normal thyroid uptake of the radionuclide, we can definitely rule out hyperthyroidism. If, on the other hand, a small hyperfunctional thyroid adenoma is found, then we know that the cat has early hyperthyroidism and could be treated.
2. The second option is to continue to monitor the cat every 3-6 months (body weight, heart rate, neck palpation, and complete thyroid profile, including serum concentrations of total T4, free T4, and TSH). If hyperthyroid, the serum T4 and free T4 should continue to go higher, where as the TSH should be undetectable (1,2,7,8). If the serum TSH is found to be measurable, that goes against hyperthyroidism since even mild increases in circulating T4 and T3 should feedback to the pituitary to shut off TSH secretion.
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 Thyroid scintigraphy in a normal cat (on right) and cat with preclinical hyperthyroidism (on left). Notice that the hyperthyroid cat has a small left thyroid adenoma with complete suppression of the right thyroid lobe. In cats with unilateral hyperthyroid disease, this lack of radionuclide uptake by the normal thyroid lobe is due to the fact that circulating TSH becomes suppressed in almost all hyperthyroid cats, even those with mild disease. |
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Either option is acceptable - just depends on what the owner wants to do. The cat is not going to be hurt by waiting, as long as he is closely monitored. At 9-years of age, he is still on the young side for being hyperthyroid, but about 5-10% of my cats are less than 10-years, so it's very possible that he is just preclinical at this time and will develop overt signs of hyperthyroidism within the next year.
For references used in creating this post, click here.
For more posts about hyperthyroidism, click here. |
• Peterson ME, Eirmann L. Dietary management of feline endocrine disease. Veterinary Clinics of North American: Small Animal Practice 2014, in press
• Peterson ME, Broome MR. Ultra-low dose radioiodine therapy is effective in cats with mild hyperthyroidism. Journal of Veterinary Internal Medicine 2014, in press
• Broome MR, Peterson ME, Kemppainen RJ, Parker VJ, Richter K. Exogenous thyrotoxicosis secondary to the consumption of commercially available all-meat dog food or treats. Journal of Veterinary Internal Medicine 2014, in press
• Rosenthal KL, Peterson ME: Hyperadrenocorticism in the ferret. In: Bonagura JD, Twedt DC (eds): Current Veterinary Therapy V. Philadelphia, Saunders Elsevier, in press
• Kintzer PP, Peterson ME. Differential diagnosis of hyperkalemia and hyponatremia in dogs and cats. In: Bonagura JD, Twedt DC (eds): Current Veterinary Therapy V. Philadelphia, Saunders Elsevier, in press
• Kintzer PP, Peterson ME. Hypoadrenocorticism in dogs. In: Bonagura JD, Twedt DC (eds): Current Veterinary Therapy V. Philadelphia, Saunders Elsevier, in press
• Meleo KA, Peterson ME. Treatment of insulinoma in the dog, cat, and ferret. In: Bonagura JD, Twedt DC (eds): Current Veterinary Therapy V. Philadelphia, Saunders Elsevier, in press
• Peterson ME, Broome MR. Radioiodine for hyperthyroidism. In: Bonagura JD, Twedt DC (eds): Current Veterinary Therapy V. Philadelphia, Saunders Elsevier, in press
• Peterson ME: The Parathyroid Glands and Disorders of Calcium Metabolism, In: Alello, S (ed), The Merck Veterinary Manual (Ninth Ed), Merial, Ltd, in press
• Peterson ME: The Thyroid Gland, In: Alello, S (ed), The Merck Veterinary Manual (Ninth Ed), Merial, Ltd, in press
• Peterson ME. Diagnosis and management of iatrogenic hypothyroidism In: Little SE, ed. August's Consultations in Feline Internal Medicine: Elsevier, in press |
The Animal Endocrine Clinic is the only clinic of its kind in the country that specializes in the diagnosis and treatment of cats and dogs with endocrine disorders. Dr. Peterson has set up two NY clinics (Manhattan and Bedford Hills) to service clients from New York City, Long Island, Westchester County, New Jersey and Connecticut.
This Clinic is separated into three divisions: the Endocrine Clinic, dedicated to diagnosing and treating dogs and cats with endocrine disorders; the Hypurrcat treatment center designed for treating hyperthyroid cats with radioactive iodine (I-131); and Nuclear Imaging for Animals, a state-of-the-art medical imaging facility where we use radioactive tracers to perform nuclear scanning (scintigraphy) for diagnosing of thyroid, bone, liver, and kidney diseases in dogs and cats.
The Animal Endocrine Clinic is a referral-only hospital, and does not offer prophylactic or routine care. We can be reached by phone at (212) 362-2650 or (914) 864-1631; by email at info@animalendocrine.com or on the web at www.animalendocrine.com. |
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