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What Does Low T3 Mean When Everything Else Is Normal?

luckypenny
February 16th, 2011, 02:47 PM
I just received Penny's thyroid test results. Does anyone know what this would indicate? Dr. Lee? Reference range is in brackets.

T4 1.64 (0.80 - 3.80)
Free T4 1.24 (0.55 - 2.32)
T3 7 (30 - 70)
Free T3 2.1 (1.6 - 3.5)

Thyroglobulin Autoantibody 1

The note attached is as follows: "Thyroid levels are normal here, despite behavioral signs. The very low T3 likely reflects a non-thyroidal issue. TgAA is normal."

What issues could that be :shrug:? We did run a CBC and blood chemistry but the samples weren't sent to the lab properly so the results are abnormal due to poor quality :frustrated:. We're going to have to redo them.

Dr Lee
February 16th, 2011, 10:58 PM
T4 1.64 (0.80 - 3.80)
Free T4 1.24 (0.55 - 2.32)
T3 7 (30 - 70)
Free T3 2.1 (1.6 - 3.5)

The thyroid gland secretes thyroxine (T4) and lesser amounts of triiodothyronine (T3). Most of these (about 99%) are bound to carrier proteins (and thus are not "free"). The remaining 1% of T4 and T3 exist in "free" (unbound) circulation. Only the free hormones (FT4 and FT3) have biologic activity and can diffuse into the tissues. Once inside the cell T3 is the active form. Luckily FT4 is readily converted into FT3. Measurement of serum T3 may not accurately reflect the physiologically active levels within the cells.

The above profile is NOT consistent with thyroid disease.

Sick Euthyroid Syndrome.

Certain diseases can lead to a reduction in thyroid levels while the thyroid gland itself is functioning normally. How this works: Illness leads to decreased binding of the protein to T4 and T3. With less bound, the free portion increases. As the free form is the biologically active form, the body will then have a "feedback loop" to decrease production of the hormones till the free portion is "normal". This is why dogs with a low T4 but a normal FT4 are not hypothyroid. The diseases possible range from stress, to dental disease, to drugs, to more serious situations.

In this case, the T3 may be artifact (lab error). It just doesn't really fit. Either way, I think your plan of just retesting is a great one. At this point, I wouldn't be too concerned over these values.

I hope this helps. :pawprint:

luckypenny
February 17th, 2011, 12:48 PM
Thank you Dr. Lee. The T3 was verified by repeat analysis. We will be doing everything all over again asap.

hazelrunpack
February 20th, 2011, 08:20 PM
Anything new in the retest, LP?

MaxaLisa
February 26th, 2011, 01:46 AM
T4 1.64 (0.80 - 3.80)
Free T4 1.24 (0.55 - 2.32)
T3 7 (30 - 70)
Free T3 2.1 (1.6 - 3.5)

Thyroglobulin Autoantibody 1

The note attached is as follows: "Thyroid levels are normal here, despite behavioral signs. The very low T3 likely reflects a non-thyroidal issue. TgAA is normal."



Things like tick diseases can affect the thyroid values.

However, there can be other things wrong with the thryoid. My boy has lower T3 values than T4, but not as bad as your dog. Associated with that is also some behaviour problems. The good thing with your dog is that the Free T3 is well within normal range, so the body is compensating for whatever is going on.

Nicholas Dodman has studied a lot of behaviour and thyroid issues, and the rule is, that behaivour problems and thyroid do not seem to follow the rules. There is some info here: http://www.germanshepherdhome.net/forum/ubbthreads.php?ubb=showflat&Number=33032#Post33032 Note the one excerpt that talks about the higher TT4.

Are you giving any supplements that contain kelp? That might throw some values off.

luckypenny
February 26th, 2011, 11:02 PM
Hazel, I'm sorry, I didn't see your last post here :o.

MaxaLisa, Thank you for taking the time to reply. Penny tested negative for tick borne disease last summer. I'll look at your link once I'm done posting here.

Is your dog hypothyroid?

We did have Penny retested immediately after the last test (1 1/2 weeks between the two sets of blood tests) and her latest results for thyroid are as follows.

T4 1.37 (0.80 - 3.80)
Free T4 1.21 (0.55 - 2.32)
T3 38 (30 - 70)
Free T3 2.1 (1.6 - 3.5)

The comment that followed these results are, "Thyroid levels are normal here, despite behavioral signs, although T4 could be higher."

I don't know what's meant by "T4 could be higher" if it's in the normal range :shrug:. I will email early in the week to see if I can have it explained to me.

Oh, and I do add a pinch of kelp to our dogs' meals but only every three days or so. I was told that Vit. D3 and Copper also play an important role in thyroid function and that raw diets can lack. I am afraid to add any more supplements than I already do if I don't know exactly what I'm dealing with here. I did start another thread when I thought I was on to something (but found out I was wrong with my original idea). If you can take a look at that too MaxaLisa and see if you can't spot something that stands out? Specifically post 36 and onwards. I would appreciate your thoughts :). http://www.pets.ca/forum/showthread.php?p=988599#post988599

luckypenny
February 27th, 2011, 01:04 PM
I'll look at your link once I'm done posting here.


Wow, that is a lot of reading. I thinks it's amazing you've taken so much time to research and post all that information, MaxaLisa. Although I think I understand some of it (at least half maybe :o), I'm not sure I can figure out how it applies to Penny, and if it does, what can I do about it.

hazelrunpack
February 28th, 2011, 02:36 PM
In our hypothyroid dogs, when we retest to make sure we've gotten the proper dosage, Dr Dodds often recommends that the T4 be near the top of the range. Not sure why she'd make the same recommendation if she doesn't think Penny is hypothyroid, though, unless she just feels that the accepted ranges for T4 levels are overall too low...

How are things going? :grouphug:

luckypenny
February 28th, 2011, 07:55 PM
In our hypothyroid dogs, when we retest to make sure we've gotten the proper dosage, Dr Dodds often recommends that the T4 be near the top of the range. Not sure why she'd make the same recommendation if she doesn't think Penny is hypothyroid, though, unless she just feels that the accepted ranges for T4 levels are overall too low...

How are things going? :grouphug:

I sent her an email asking if she could explain. I'll let you know what her answer is as soon as I get a reply.

Things are the same. I have to stop Lucky and Nukka from rough playing because Penny gets upset when they do, especially when Lucky gets growly (in play) or when one of them yelps. And then I have to get mad at Penny when she goes stupid but I get frightened at the same time. Most times I just want to lock myself up in a room and hide :o.

aslan
February 28th, 2011, 08:13 PM
LP,,just curious is Penny really protective of either Lucky or Nukka? We've noticed Q is getting a little huffy if the other two are playing rough and growling,,and lord help us if one of them yelps..Is she possibly trying to protect whomever she favors?

luckypenny
March 1st, 2011, 07:42 AM
She'll go for either one, Aslan. She's also prefers to spend her time away from them during the day...she just went back to hiding out in the basement :shrug:.

Hazel, the reply I received late last night..."The T4 level can be lowered not only from hypothyroidism, but also from any other illness, abnormality, or use of certain drug (steroids, anticonvulsants, sulfonamide antibiotics). "

She recommends after about 6 weeks of supplements and a liver sparing diet, to have Penny's serum chemistry profile redone.