Conflicting Hypothyroid Opinions

[Guest rachelee]

After Bistro had his weird 'episodes' the neurologist said to do some digging on hypothyroid. We just got the results back and I sent them to both Dr. Couto and Jean Dodds. The problem is Couto says they're normal and Dodds says he's hypothyroid.

 

Bistro hasn't had an episode since the 2 he had within 24 hours. He acts totally normal and doesn't seem to have any symptoms at all. He's pretty high energy for a grey and has a ton of fur. His results are below.

 

4 <0.4 (ref 0.9-3.9) VERY LOW 0.9-2.0 ug/dL

 

Free T4 <0.2 (ref 0.7-3.7) VERY LOW 0.46-1.2 ng/dL

 

TSH 0.15 (ref 0.05-0.42) Discordant < 0. 35 [see attached explanation]

 

TGAA 12% (ref <20%) NORMAL < 0. 35

 

I'm inclined to not do anything since he's been healthy, but if there's any symptoms, perhaps try the meds.

 

What do you think?

[Batmom]

The numbers show he's normal. Greyhounds can have fT4's extending to zero -- that is, too low for the existing instruments to measure.

 

 

[ahicks51]

Who ran the samples for the test?

[Guest rachelee]

Who ran the samples for the test?

 

Not sure -- I got the tests done at my local vet in Somerville, MA. The first list of reference was what I got from my vet, the second was from Dr. Dodds.

[Batmom]

I just noticed the double reference ranges.

 

Throw out the set you got from Dr. Dodds. I'm not sure why she would think it appropriate to give them to you. Reference ranges are specific to individual laboratories -- you can't apply one lab's ref ranges to another lab's results.

[seeh2o]

You know, rather than relying on the best guesses of laymen (most of us here on GT), I'd send Dr Couto and Dr Dodds each other's opinions and ask them why the difference in interpretation and go from there. Better to go back to the source(s) of confusion as they are the experts.

 

Edited to add that if you do that, I'd be fascinated to hear what they have to say!

Edited December 30, 2009 by ckruzan

[ahicks51]

Who ran the samples for the test?

 

Not sure -- I got the tests done at my local vet in Somerville, MA. The first list of reference was what I got from my vet, the second was from Dr. Dodds.

 

Almost certainly done by IDEXX or the other commercial lab whose name I can't recall. Labs like MSU and (presumably) Dr. Dodds run theirs after dialysis, meaning the solution is concentrated so that the compounds will be present in a sufficiently high concentration that the instrumentation can read the figures that low.

[Batmom]

ahicks, AFAIK Dr. Dodds doesn't do equilibrium dialysis. MSU and Antech do. Not sure about IDEXX.

Edited December 30, 2009 by Batmom

[Guest Energy11]

I trust Dr. Couto, who reviewed Curfew's numbers. The is just MY opinion.

[CaliforniaGreys]

You know, rather than relying on the best guesses of laymen (most of us here on GT), I'd send Dr Couto and Dr Dodds each other's opinions and ask them why the difference in interpretation and go from there. Better to go back to the source(s) of confusion as they are the experts.

 

Edited to add that if you do that, I'd be fascinated to hear what they have to say!

 

I agree with Connie. Dr Dodds and Dr Couto know each other very well, it'll be interesting to hear what they have to say

Edited December 30, 2009 by cbudshome

[brandimom]

I kind of had a similar situation. Dr. Dodds does not do TSH. When I got the results back from Dr. Dodds I sent it to OSU for their opinion and they said they needed the TSH.

[Guest rachelee]

The neurologist just called me and said he thinks we should put him on the meds. He says Dr. Dodds' recommended level is fine -- a nice, low dose. 0. 1 mg of brand name [soloxine or ThyroTabs, rather than generic] thyroxine per 20 pounds of body weight twice daily. Bistro is 78 lbs, so that's 0.4 mgs twice per day.

 

I think I'll email Dr. Couto with these two other assessments and see what he says.

[seeh2o]

The neurologist just called me and said he thinks we should put him on the meds. He says Dr. Dodds' recommended level is fine -- a nice, low dose. 0. 1 mg of brand name [soloxine or ThyroTabs, rather than generic] thyroxine per 20 pounds of body weight twice daily. Bistro is 78 lbs, so that's 0.4 mgs twice per day.

 

I think I'll email Dr. Couto with these two other assessments and see what he says.

 

Just and FYI from a layman, but lots of people here have had good luck using Soloxine. I had Carl on the generic thyroid medication for several months and saw no improvement in his eyes or his fur, then switched him to Soloxine, his eyes were better within a month and his coat had improved as well. I don't know why it seems to be better than generic, though, but there was improvement with it.

[Guest grey_dreams]

Part of the conflicting opinion probably arises from different interpretations of the TSH test. The TSH test is an ELISA assay, which uses an antibody against the hormone to determine how much TSH is present. The accuracy of the test relies on the accuracy of the antibody. There are data that indicate the antibody - that has historically been believed to be very accurate - has a very low rate of accuracy.

 

So the test values for TSH have the potential to be very skewed and not reliable.

[Batmom]

Part of the conflicting opinion probably arises from different interpretations of the TSH test. The TSH test is an ELISA assay, which uses an antibody against the hormone to determine how much TSH is present. The accuracy of the test relies on the accuracy of the antibody. There are data that indicate the antibody - that has historically been believed to be very accurate - has a very low rate of accuracy.

 

So the test values for TSH have the potential to be very skewed and not reliable.

 

Can you supply references?

 

MSU, who does an enormous amount of research on this (and whose lab is the only one I and most of my vets will use for testing), has found the TSH test to be pretty accurate. Like any test, it isn't perfect.

 

MSU's FAQ section for thyroid testing can be found here: http://www.animalhealth.msu.edu/Sections/Endocrinology/Thyroid_Canine.php#10

 

The trouble with NOT using the TSH test in greyhounds is, unless the greyhound has hypothyroid-specific symptoms for which no other explanation can be found, there really is no way to know that the dog is hypothyroid. The autoantibody tests that some labs (Dr. Dodds I believe) rely on may show a disease process but don't show whether the dog is hypothyroid.

 

That's a problem. Supplementing with thyroid hormones is often regarded as benign, even if the dog doesn't need it. That isn't true. Excess thyroid hormone can cause a multitude of problems, including tremors, seizures, and of course the classic crabbiness/aggression, nervousness, and weight loss. It can be particularly harmful to supplement if the dog has a heart problem or another endocrine condition.

[Guest grey_dreams]

The TSH values have to be considered alongside the other tests and the dog's condition. So it seemed to be valid, for the case in the OP, for the vets to suggest running a trial evaluation with low dose. I just wanted to note that if all other results suggest hypothyroid, a "low-normal" TSH value shouldn't negate the decision to run a trial treatment.

 

 

Can you supply references?

 

Yes

 

Taken from the MSU site that you linked:

"Unfortunately, current assays for canine TSH do not have sufficient sensitivity to differentiate normal from low concentrations."

And:

"The second possibility (if clinical evidence for hypothyroidism is strong and there is no illness or interfering medication identified) is that the animal truly has hypothyroidism but it is one of approximately 15% of cases in which TSH is not found to be elevated."

 

Here is a summary from a vet prof. who has cloned and expressed recombinant cTSH, which could be used to raise monoclonal antibodies, which would have much greater accuracy than polyclonals for the ELISA tests:

 

Recombinant Thyrotropin (TSH): Standard for the Next Generation of Canine TSH Immunoassays with Improved Sensitivity

 

Researcher: Duncan Ferguson, DVM, PhD, University of Georgia

 

Hypothyroidism, a failure of the thyroid gland, is the most common hormonal abnormality in dogs, causing a variety of medical problems in many breeds, including hair loss and skin infections.

 

The measurement of serum levels of the pituitary hormone thyrotropin (TSH) has been used as a reliable and sensitive screening test for thyroid glandular insufficiency in human medicine for many years, but the "first generation" assays for canine TSH (cTSH) are missing as many as 1 out of 4 cases of hypothyroidism, resulting in no improvement in diagnostic sensitivity compared to total T4 measurement. Furthermore, the available assays have not been sensitive enough to distinguish low values of cTSH from those in the normal range. Towards the goal of improving current and future immunoassay sensitivity based upon a pure recombinant canine TSH (cTSH) hormone standard, our laboratory has succeeded in cloning and sequencing the two peptide subunits of canine TSH and have expressed them in small quantities. Using techniques recently developed in our parallel work on equine TSH, we plan to express and purify recombinant canine TSH in high quantities and validate its use as a pure immunoassay standard to facilitate its worldwide use.

 

Other References

● Dixon RM, Graham PA, Mooney CT. Serum thyrotropin concentrations: a new diagnostic test for canine hypothyroidism. Vet Rec 138: 594-595, 1996.

● Iverson L, Jensen AL, Høier R, et al. Biological variation of canine serum thyrotropin (TSH) concentration. Vet Clin Pathol 28:16-19, 1999.

● Jensen AL, Iversen L, Høier R, et al. Evaluation of an immunoradiometric assay for thyrotropin in serum and plasma samples of dogs with primary hypothyroidism. J Comp Pathol 114: 339-346, 1996.

● Diaz Espineira MM, J.A. Mol JA, Peeters ME, Pollak YWEA, Iversen L,van Dijk JE, Rijnberk A, Kooistra HS. Assessment of thyroid function in dogs with low plasma thyroxine concentration. J Vet Intern Med 21:25–32, 2007.

 

 

Here is another reference I found on PubMed (but I'm not at work so can't download the article):

 

Vet Clin North Am Small Anim Pract. 2001 Sep;31(5):951-62

 

Diagnosis of canine hypothyroidism. Perspectives from a testing laboratory.

 

Kemppainen RJ, Behrend EN.

Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Endocrine Diagnostic Service, Auburn, Alabama, USA.

 

The most common sample received by our endocrine testing laboratory is submitted for the diagnosis of hypothyroidism in a dog. The current tests most frequently employed in our laboratory for thyroid evaluation in dogs are total T4, free T4 by dialysis, and canine TSH measurement. Each test has strengths and weaknesses and suffers from the possibility of both false positive and false negative results. This article provides a working description of each test and an approach to interpretation of results. Other tests that are less commonly used are also discussed. Examples of interpretation of test results in individual hypothyroid-suspect dogs are presented for illustration.

[Batmom]

Thanks, I've seen those.

 

It's certainly true that TSH isn't the only test in town nor perfect, but on the low end it isn't relevant IMHO. You don't need to distinguish between low and normal TSH to support (or not) a diagnosis of hypothyroidism, only between low/normal and high.

 

For a greyhound, I think maybe missing 15% is still a pretty good test. You can't tell by hair loss (greyhounds do it normally), can't tell by general activity level (greyhounds are lazy normally), can't tell by cold tolerance (greyhounds don't have much normally) ..... so for me, any port in a storm.

 

That is why I always send to MSU, though. Their endocrinologists are well aware of the test limitations, the current research (other people's as well as their own), and the scope of greyhound oddities so I feel confidence in their interpretations.

 

In OP's case, the dog doesn't have symptoms barring an isolated incident. All the dog's markers seem to be for NONhypothyroidism. So it would seem odd to me to do a trial of the medication -- neither symptoms nor test results to support it, and no symptoms to judge whether the medication is helpful or not.

 

 

[duncan41]

Thanks, I've seen those.

 

It's certainly true that TSH isn't the only test in town nor perfect, but on the low end it isn't relevant IMHO. You don't need to distinguish between low and normal TSH to support (or not) a diagnosis of hypothyroidism, only between low/normal and high.

 

For a greyhound, I think maybe missing 15% is still a pretty good test. You can't tell by hair loss (greyhounds do it normally), can't tell by general activity level (greyhounds are lazy normally), can't tell by cold tolerance (greyhounds don't have much normally) ..... so for me, any port in a storm.

 

That is why I always send to MSU, though. Their endocrinologists are well aware of the test limitations, the current research (other people's as well as their own), and the scope of greyhound oddities so I feel confidence in their interpretations.

 

In OP's case, the dog doesn't have symptoms barring an isolated incident. All the dog's markers seem to be for NONhypothyroidism. So it would seem odd to me to do a trial of the medication -- neither symptoms nor test results to support it, and no symptoms to judge whether the medication is helpful or not.

 

Very well said. I think Dr. Couto said as much at Sandy Paws 2008 - when it comes to the thyroid, he treats based on symptoms, not test results.

[Guest grey_dreams]

Thanks, I've seen those.

 

Oh, I thought you didn't know that work, and that's why you asked for references

 

It's certainly true that TSH isn't the only test in town nor perfect, but on the low end it isn't relevant IMHO. You don't need to distinguish between low and normal TSH to support (or not) a diagnosis of hypothyroidism, only between low/normal and high.

The error is linear, so it skews the same whether the result is in the low/normal or normal/high range.

 

For a greyhound, I think maybe missing 15% is still a pretty good test...

The current test has an error rate of 15-25%. In scientific terms, that's a WHOPPING error rate.

 

In OP's case, the dog doesn't have symptoms barring an isolated incident. All the dog's markers seem to be for NONhypothyroidism. So it would seem odd to me to do a trial of the medication -- neither symptoms nor test results to support it, and no symptoms to judge whether the medication is helpful or not.

The original values posted with the reference range from the lab that did the test returned all values as very low except TSH.

 

Anyway, it's up to the OP to decide if her dog warrents a trial treatment. I just wanted to add what I knew about the inaccuracy of the TSH test

[Guest TeddysMom]

Do any of you use any natural or herbal supplements to support and maintain the thyroid in greyhounds? Not to actually treat a problem but just for general care. I am just curious.

[seeh2o]

Do any of you use any natural or herbal supplements to support and maintain the thyroid in greyhounds? Not to actually treat a problem but just for general care. I am just curious.

Carl is on an adrenal supplement in addition to Soloxine. He is on Drenatrophin by Standard Process.

 

Edited to add that so is my non-grey who developed SARDs four years ago. From what I've read, the majority of dogs with SARDs don't have a long lifespan after SARDs and many go on go on to develop Cushings. I don't have any proof, but I really feel that Sheila is alive and well at the ripe old age of 14 because of the Drenatrophin.

Edited December 31, 2009 by ckruzan

[brandimom]

Do any of you use any natural or herbal supplements to support and maintain the thyroid in greyhounds? Not to actually treat a problem but just for general care. I am just curious.

 

Brandi and Lexi are on Soloxine, low dosage, but we do go through Marina at www.naturalrearing.com or some herbal supplements. We have them on Standard Process Thytrophin PMG, 2 pills each in the a.m. and p.m. We also do Metabolic Complex, 1 in the a.m. and 1 in the p.m. After they have been on them for a couple of months we are going to have them retested. This time I think we will go through MSU.

[Guest ishapespace]

Anyone using kelp (iodine) as a thyroid supplement?

[seeh2o]

Anyone using kelp (iodine) as a thyroid supplement?

Carl is on .7mg of Soloxine a day (I split one .7mg pill, he gets half in the am half in the pm). When I was talking about using a supplement for the dogs my vet saw that it had kelp in it and she said "absolutely not", that it could interfere with his thyroid treatment.

[Guest Greytluv]

All my dogs are Hemopet dogs and Hemopet does all their blood work. I do what Dr. Dodds says.