# Why would FT4 go down, TT3 stay same while TSH drops?



## nvsmom (Sep 30, 2012)

I had labs done a while ago and am trying to understand why I had some of the results that I did. When my synthroid was changed from 50 mcg to 75 mcg my:


TSH dropped from 7.55 to 5.86 (ref 0.2-6.0)
Free T4 dropped from 15.3 to 14.3 (ref 10.0-25.0)
Total T3 stayed at 1.3 (ref 1.1-2.8)

*Why would my FT4 drop?* I did not take synthroid that morning and the test was at about the same time of day. Before treatment when my TSH was in the teens it was 11.6 so I know it can go up...

*Why would my T3 not move?* If my T3 is the same, wouldn't my pituitary put out the same amount of TSH to get it going?

Any guesses as to what is going on? My doctor is of no help so I need to figure this out on my own. Thanks.


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## smelliebellie (Oct 14, 2012)

how are you feeling? thats whats important. ive been told a couple things from veteran hashis and doctors. 1) the timing of when you got your blood work done can interfere with your results. 2) if your ft3 goes up, you may not have a problem converting. 3) since your ft3 didnt move, you need to give your medicine time to work and build up in your system.


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## sjmjuly (Mar 23, 2012)

Someone with more experience can chime in here, but I don't think T3 "builds up" in your system. T4 does, but converts to T3 and is used as the body needs it. T4 has a longer "shelf life" than T3 does. I take a dessicated thyroid that contains both T3 & T4, and I can tell when my T3 runs out. 
I do agree that timing is a factor. I take my pill at 4:00 AM and if I test first thing in the morning, my levels will be different than if I test in the afternoon.


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## nvsmom (Sep 30, 2012)

smelliebellie said:


> how are you feeling? thats whats important. ive been told a couple things from veteran hashis and doctors. 1) the timing of when you got your blood work done can interfere with your results. 2) if your ft3 goes up, you may not have a problem converting. 3) since your ft3 didnt move, you need to give your medicine time to work and build up in your system.


I don't feel any better than I did before treatment began; I still feel hypo. Well, change that... those tests were a month ago and my dose is now 100mcg and I feel a little bit better.

Both tests were done at lunch time and my last dose of levothyroxine was 32 hours earlier, give or take an hour. I believe levothyroxine can stay in your system for about a week so timing shouldn't make a huge difference as long as I'm pretty regular.... I think.

I think T3 stays in the body for only a day, and I don't take any T3. I had been on the previous dose somewhere between 7 and 8 weeks so my body should have adjusted to it. It is entirely possible that amount of time wasn't enough for my body to adjust.

Thanks. 



sjmjuly said:


> Someone with more experience can chime in here, but I don't think T3 "builds up" in your system. T4 does, but converts to T3 and is used as the body needs it. T4 has a longer "shelf life" than T3 does. I take a dessicated thyroid that contains both T3 & T4, and I can tell when my T3 runs out.
> I do agree that timing is a factor. I take my pill at 4:00 AM and if I test first thing in the morning, my levels will be different than if I test in the afternoon.


I am pretty regular with my levothyroxine times. I will occasionally move up or back an hour or so but I'm pretty consistent. I always have my labs done just before lunch, and I don't take that days usual early morning dosage until after my test. ... I did that on both test dates.

Since I don't take any T3 (although I'd like to) my timing for testing and pill taking shouldn't need to be too exact. I've heard that a missed day can make quite a difference with T3, unlike the T4.

Thanks.


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## Lovlkn (Dec 20, 2009)

Lab error.

How much water do you drink when you take your Synthroid?

I am a firm believer that you must drink enough water to help dissolve the pill and get it into your system. As simple as that is I believe alot of people do not drink enough water.

If you have added any vitamins or supplements, that also could affect your absorption


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## smelliebellie (Oct 14, 2012)

Oh really? I take my synthroid with just a sip of water just to get it down. I didnt know i had to take it with lots of water


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## nvsmom (Sep 30, 2012)

Lovlkn said:


> Lab error.
> 
> How much water do you drink when you take your Synthroid?
> 
> ...


I've never drank water with my synthroid because I've had no problem swallowing pills in the past. It is definitely possible that I should be drinking more water with my synthroid but I don't think that would affect just my last test because I've never taken it with water... unless i accidently had a glass of water shortly afterwards.

I'm very careful not to take my vitamins within a couple of hours of taking my meds; especially my calcium. I've accidentally taken vitamins within an hour of my meds once or twice in the past 5 months but I realized my error immediately. I;m usually careful so i don't think that's it.



smelliebellie said:


> Oh really? I take my synthroid with just a sip of water just to get it down. I didnt know i had to take it with lots of water


I didn't know this either. I know I've heard that we should avoid taking it sublingually (dissolve in mouth) but i can't remember where I read that.

I should probably drink more water regardless of how i take my meds.


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