Thyroid UK
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optimal FT3 levels on NDT?

Could anyone please tell me what your labs should look like if optimally dosed on Armour/NDT...? I know the TSH is deemed unimportant, as it's often suppressed when on drugs containing T3, but I am more interested in finding out what the FT levels should look like...or, more precisely, the FT3 levels. As far as I know, we are supposed to go to the lab 24 h after taking drugs containing T3. If that is correct, what should our FT3 levels look like when we go to the lab, when we are optimally medicated...?

Or, in case we don't need to wait 24 hours before going to the lab...what should your FT3 levels look like right after you've taken NDT?

I realise there are no exact rules, but I'd nonetheless appreciate some guidance on this.

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In an article someone posted the other day, T3 will peak around five hours after taking the day's dose. I guess if that is what you want to know....... but perhaps you'd rather see how low it goes rather than how high it is. To tell you the truth I don't know if it would be the same if you are taking T3 only or T3 with T4? Normally FT3 should be in the upper part of the range given but also according to how you feel I would think.

Dr. Lowe is the only doctor I have heard of that took T3 only. You could go to the website and see if anything has been stated regarding your question.

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There is a peak of T4 around two hours after taking a dose of levothyroxine.

There is a peak of T3 around one-and-a-half hours after taking liothyronine.

There is a peak of T3 around 48 hours after taking a dose of levothyroxine.

These are all approximate and may vary between people to some extent.

I do not know how the equivalent peaks occur from taking desiccated thyroid.

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Where did you get the 1 1/2 hour peak, Rod? I'll try to find my reference.

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Right now, I take Armour Thyroid (5 grains daily). This is what my latest labs looked like, about 24 h after taking any Armour (labs from 21/10 2015):

FT4 1.12 (ref 0.7-1.4)

FT3 2.92 (ref 1.7-3.7)

TSH 0.01 (ref 0.4-4.0) suppressed

What I want to know, more than anything, is if this indicates that my FT3 levels are suboptimal and, if so, how to raise them...raise Armour? Or switch to an NDT drug without cellulose?

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Anna, >3.0 is optimal. You're slightly shy of that. If you feel hypo raise Armour dose a little.

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I am not a medical professional and this information is not intended to be a substitute for medical guidance from your own doctor. Please check with your personal physician before applying any of these suggestions.

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They look good, Anna and probably should be with such a high dose. The conversion looks fine. There is room if you feel the need. I wonder if taking T3 and reducing Armour would be helpful. I haven't read your history/profile. Maybe you have already tried other things.

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Thanks to both of you, Heloise and Clutter!

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So, are we looking for FT4 & FT3 results in upper quadrant

of ref range BEFORE we take daily meds ? If so then

presumably could go over range after taking meds ?

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Good question, I have been asking myself the exact same thing!

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I think you lose as much as you gain each day when you have reached your optimal dose. It's like adding a teaspoon to a bowl of water that evaporates a teaspoon a day.

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Ah, thanks

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Anna69, when optimally dosed, FT3 will usually be in the top third of range. Clarebear took 2.5 grains a couple of hours before a blood draw. FT3 was 15 but was usually around 5 24 hours after last dose.

____________________________________________________________________________________________

I am not a medical professional and this information is not intended to be a substitute for medical guidance from your own doctor. Please check with your personal physician before applying any of these suggestions.

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Ok, thanks Clutter.

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OK, so just to be clear about this: should we take meds containing T3 BEFORE going to the lab??? I always waited until afterwards, and always made sure I had not taken any thyroid meds for 24 h when having blood drawn.

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Anna69, ALL thyroid meds, T4 and T3, should be taken after the blood draw. You've been doing it the right way by leaving 24 hours between last dose of NDT and blood draw.

_________________________________________________________________________

I am not a medical professional and this information is not intended to be a substitute for medical guidance from your own doctor. Please check with your personal physician before applying any of these suggestions.

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Thanks, Clutter, that is just what I thought!

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Can someone explain this concept to me? All these years my doctor has never told

Me don't take your meds 24 hours before a draw.

How does this work? If we don't take the meds the labs will just say we need more meds and thyroid function is off. Aren't we suppose to be checking if the dose we are on is doing its job by getting blood drawn on the meds?

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I am glad you asked that question, because I am also beginning to find it confusing...the main reason my doctor said Armour did not seem to be working optimally for me was because I had blood drawn 24 hours after taking my meds, and my FT3 levels were about mid-range...

What I have been told in the past is that the T3 in drugs like NDT and synthetic drugs like Cytomel will raise our FT3 levels so much that it will look like we are overmedicated. I just don't know if that is correct, or if it is like you say; that is, that in order to know how a given drug works for us (in terms of absorption), we need to get blood drawn on the meds...? After my own experience with Armour, I'd be tempted to say you're right...if T3 has such a short half-life (I have read 12-24 hours), most of it is likely gone from our bloodstream 24 h after taking meds...

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