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Old 02-04-2013, 09:14 PM   #9
telus telus is offline
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Re: Month 11 - labs confusing

Hi Brussel,
I have been pondering your dilemma for a while. It looks like you may be approaching the point where some people throw up their hands and say natural thyroid does not work for me! I hope that you will not.

I agree entirely with the other posters who have responded to you, however I'd like to try to explain what I think is happening.

First, backup for a minute and consider what your natural normal thyroid produces. A normal thyroid produces about 90 to 100 mcg of T4 and 6 mcg of T3 per day. Some of the T4 is converted by your tissue for a further 24 mcg of T3. If you assume you only absorb 80% of T4 meds, then you need to take 112.5 to 125 mcg to absorb 90-100 mcg.

Second, in the old days doctors found that about 180 mg natural desiccated thyroid (NDT) was kind of the minimum dose that people worked up to, which in the case of ERFA Thyroid contains 106 mcg T4 and 24 mcg T3. Think of this as a minimum "full replacement dose". So you can see why this would be the case, because these number are kind of similar to what a normal thyroid puts out.

Now let's look at what happened when you were on 90 mg Thyroid, which contains 53 mcg T4 and 12 mcg T3. The T3 enters your blood stream fairly rapidly and your T3 level is now high enough to trigger the TSH to go low. TSH is what tells your thyroid to make thyroid hormone, so if TSH is quite low, your thyroid is essentially "turned-off" - it does not make any more T4 or T3. But now you have a problem. You only take 53 mcg of T4 but your body needs around the 90-100 mcg T4, and your thyroid is turned-off. So you are going to be short of T4 and that is going to make you feel hypo. You can see that both your FT3 and FT3 were lower in December than in the October tests. I think that is indicative of your T3 and T4 stores being used up due to your thyroid being shut off.

So, long story short - if you go on to Thyroid you usually need to take a full replacement dose so that you get enough T4 and T3. And it is a typical mistake that doctors make - they don't increase the dose fast enough, because as you can see, once your thyroid is shut-off your are going to start to be hypo if the T4 dose doesn't get increased to a full replacement level.

It is hard to say if 75mg Thyroid will have enough T3 to keep your thyroid shut-off. If it does, then that will be worse because your T4 will be lower yet. On the other hand it may not keep your thyroid shut off and it is possible that your thyroid has enough capacity to make up the gap to your full requirement.

I guess our concern is that your doctor may not be familiar with this situation.

 
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brusselsgriffon (02-04-2013)