Retesting Thyroid Levels

[tydyelady]

Opie has been on Thyroid medication after testing him a number of years ago. My vet wants to retest him before continuing with his current pill levels, and I in fact, after becoming more educated, am questioning whether he needs to take the supplement at all. I will request a full panel, which he has not had before, just the T4 levels, which were VERY low. So my question is - when I take him for the test, should I take him off the medication to get a result of how he is naturally, or should he test with taking his thyroid medication? Thanks for any help in this. I hate to have him on thyroid meds if he really doesn't need it.

[tbhounds]

Don't change a thing. Check the T4 4-6 hours after he received the soloxine. To run a full panel he needs to be off the medication completely for at least 6 weeks per MSU.

Cudos to you for doing your homework and realizing that a full panel should have been run initially.

Edited to add that if you choose to try and stop the soloxine wean down slowly over time--per Dr Couto-- he does not recommend stopping the soloxine abruptly.

Edited January 30, 2012 by tbhounds

[GeorgeofNE]

He's been on it for multiple years without a retest?

 

That's unbelievable. When my dog went on it (my non-Grey) they tested him multiple times in the first few months to get the level correct, and then annually.

[Batmom]

As tbhounds notes: There's no point in getting a full panel unless he's off the medication completely for a full 6 weeks.

 

All you can do right now, today, is check his levels to see if the amount of medication he's getting is appropriate.

 

If you suspect he shouldn't be on the medication at all, then you could take him off it, wait the 6 weeks, and do a full panel then. I'm not convinced it's necessary to wean the dog off (because of how thyroid hormones / reserves work) but it certainly can't hurt to do that rather than quitting cold turkey.

[tydyelady]

He was tested a few times after during the first year, and then a year later. No, it wasn't just take this and run. But not the full panel. Well this is interesting, can test T4's while taking it, but 6 weeks off for full panel. OK, I will discuss this with my vet too then and get her input.

[greyhead]

We just retested Spencer with a full panel, without taking him off the medication, and I believe we still got useful results. His fT4 was way high. So the vet said to cut his dosage in half. The whining at night, which is what led to our decision to retest at this time, has stopped entirely on the new dosage. Although the vet didn't say anything about it, I imagine we'll retest again in a couple of months. Just sharing our experience, not recommending that you follow any particular path.

 

ETA: We had our panel run locally through Antech, who does test fT4 through equilibrium dialysis. But I think it wound up being significantly more $$ than what I've heard MSU charges for their panel, so you might want to investigate that. Oh, and scritches to Opie!

Edited January 30, 2012 by greyhead

[Hubcitypam]

That is so weird to me that dogs need six weeks off meds and for the last 30+ years they have done full thyroid panels on me while I was on my meds to see if they needed to be adjusted.

Why the difference?

[Batmom]

If you're running a full panel while the dog is taking thyroid medication, it won't tell you anything about the dog's native thyroid function (which will normally be suppressed). Some useful info here: http://www.dcpah.msu.edu/Sections/Endocrinology/Monitoring.php . MSU does offer a monitoring profile but unless the dog is having issues I honestly don't know that that buys you much more than a plain T4 for judging the adequacy of dosing.

[greyhead]

Batmom, in Spencer's case recently, his T4 looked entirely normal. Without the fT4, we wouldn't have known it was a problem. The fT3 was high too.

 

(Just as an aside, it's surprising to me that he'd have such excess fT4 in the absence of excess T4. I have to wonder if Spencer's IBD status and diet have a bearing on the situation.)

[Batmom]

In most cases, if there were a problem such as inadequate or excess dosing, you'd see some symptoms. Spencer's case might indeed be complicated by his IBD -- he has a symptom, and you don't know which thing it's coming from!

 

fT4ed (free T4 by equilibrium dialysis) is a more accurate method of measuring available hormone. It's considered the "gold standard" and the reference method (the one used as a comparator for other methods). Why it's more accurate has to do with fun things like what's protein-bound and what's not, how the different assays work, etc.

 

Full thyroid panel while on meds: In that case, it's a monitoring profile, like MSU's. The TSH measurement included in that panel (and in a dog's monitoring profile) is included to gauge the overall efficacy of the dose of thyroxine or other meds that one is taking. Since T4 levels can vary greatly, the TSH measure in particular helps the doc (or vet) gauge whether the dose of synthetic hormone being taken is adequate.

 

That said, I'm not sure how much T4 levels really vary in a supplemented greyhound whose blood is tested at @ the same time after dosing. So I'm not sure how useful the whole monitoring panel really is in an uncomplicated case.

 

 

 

 

 

I have to review all this ... stuff ... for a giant exam on Friday so maybe I'll have more comments (other than cuss words) later :lol .

[JJNg]

That is so weird to me that dogs need six weeks off meds and for the last 30+ years they have done full thyroid panels on me while I was on my meds to see if they needed to be adjusted.

Why the difference?

As Batmom mentioned, the full thyroid panel while on meds is done as a monitoring profile. In the OP's case, she is wondering if the dog needs to be on thyroid supplement at all. Weaning off medication, waiting 6 weeks, then checking a full thyroid profile would be to determine whether the dog is truly hypothyroid (which wasn't adequately established by the original testing prior to starting supplementation).

 

Additional questions I ask owners in a case like this are:

 

1) What were the original symptoms which prompted thyroid testing and supplementation to begin with?

 

2) Did those symptoms improve/resolve after thyroid supplement was started?

 

3) If the owner decides to try weaning off thyroid meds, do those original symptoms return?

 

IMO, if a greyhound did not have any clinical signs to begin with, and did not show any changes/improvement after starting thyroid supplement, it probably doesn't need to be on the meds.

[gr8kids]

Thyroid is a tricky area for the GH. I recommend going to the Hemopet website w/Dr. Jean Dodds who does research w/the panels of greyhounds and there are more #s to look at than T4 and T3.

 

the website is http://www.hemopet.org/ She is in Garden Grove,CA and has a greyhound rescue and has blood donor program and a great way to test for allergies w/the dog saliva. She is an amazing lady.

I've worked with her, very educated and an edocrin specialist vet. She does lectures across the country and will answer your email.

 

Also recommend to get your dog checked at least yearly to make sure its working right.

Soloxin is sensitive to soy and dairy and you need to try and give it every 12 hrs b/c of its half life, doesn't last more than that.

 

Kathy

[tydyelady]

Thanks for all these replies. I believe I am going to get Opie tested for a full panel, without the meds. His original symptoms were some aggression, but I know and have learned that it was me, not reading his signs, allowing him too many privileges in the beginning, and not doing proper training as me as the leader. He was new to our household at the time (3 months), and he was beginning to test his boundaries. Plus the fact that I was playing with him, on the floor, on his bed, and did not read his signals of "leave me alone" and he snapped at my face, hitting me with his canine tooth and drawing blood. YES, I have since learned a LOT, and Opie is the sweetest big goofy boy ever now. It will be 5 years in March that we have him now. He never had any other symptoms. His diagnosis was based on VERY low T4 levels, which the lab actually retested because they were so incredibly low (lower than the low end for greyhounds) I was given the choice of a full panel at the time, but I did not know then what I know now. So that is what we will do, probably in a few months.