T3 lowers FT4

[Philipp_Winsel]

Hello,

i’m on T3+T4... Since I started T3 my FT4 dropped significantly... Do you need to take more T4 to achieve same FT4 levels when taking T3 compared to T4 alone ?

[SeasideSusie Remembering]

Since I started T3 my FT4 dropped significantly...

This is what happens when adding T3, or taking NDT (as it contains T3), FT4 will lower and TSH will as well, often becoming suppressed.

Do you need to take more T4 to achieve same FT4 levels when taking T3 compared to T4 alone ?

Not as a general rule.

Depending on where your FT4 lies within it's range (or over range) before adding T3, sometimes it's necessary to reduce Levo before adding T3 if FT4 is high.

Once on combination therapy, it's up to us to find out what dose of each hormone gives us an FT4 and FT3 level where we feel best, it's very individual. Some people do well with quite a low FT4 and highish FT3, some of us need a higher FT4 more in balance with our FT3. This is why adjustments should be gradual, in small amounts and over time, leaving 6-8 weeks between dose adjustment for levels to settle so that we can see how we feel and how are hormone levels have changed.

[Philipp_Winsel in reply to SeasideSusie]

my FT4 dropped from 21 to 10 (10-22) on 125mcg T4 . Would like it to be around mid range..

[SeasideSusie Remembering in reply to Philipp_Winsel]

my FT4 dropped from 21 to 10 (10-22) on 125mcg T4

It wouldn't have dropped all in one go by reducing your Levo from 150mcg to 125mcg.

Over what period of time are you talking about?

Did you increase your dose of T3 during this time?

Have you tested regularly?

Do you do your tests the same every time, i.e. last dose of Levo 24 hours before test, last dose of T3 8-12 hours before test, same time of day for every test?

Perhaps you can chronicle your test results/doses of Levo and T3 since the time you've added T3 to your Levo so we can see what sort of pattern is emerging and we may be able to give more useful reponses.

Would like it to be around mid range..

Do you know that you will feel better - symptom-wise - with it mid-range?

Do you have a set of results where you did actually find your sweet spot and know exactly where you need your levels to be?

[Luna1390]

Hi there!

So the same thing happened to me when I started NDT. I was on it for a year & my FT4 stayed low. This seems to be okay for some people. But I, personally, still did not feel totally good.

I found the website & book for The Tired Thyroid. The author discusses people like me who seem to need more T4. I discussed it with my doctor & she added a small amount of Synthroid to my NDT. My T4 came up to mid-range and I feel totally normal now. It has been 9 months since I added Synthroid. It seems we each are so different. This may or may not be what helps you. But it may be worth a try!

[adin in reply to Luna1390]

Interesting observation, how much t4 you take?

[Luna1390 in reply to adin]

Just 25 mcg.

[SlowDragon Administrator]

So were you on higher dose of Levothyroxine before T3 was added?

How long have you been on 125mcg Levothyroxine and how much T3 are you currently taking?

Often endocrinologists will reduce Levothyroxine by 25mcg or sometimes 50mcg when adding in T3. This often soon results in FT4 dropping too low.

When endocrinologist added T3 to my Levothyroxine, Levo was reduced from 125mcg to 100mcg. Initially 2 x 5mcg T3 added. After 8 weeks and blood test, T3 increased to 20mcg (split into 3 doses - 10mcg, 5mcg and 5mcg)

Before Levothyroxine was reduced my FT4 was always 17-19 (range 12-22)

After 16 weeks on reduced Levothyroxine, FT4 dropped to 13. Started to see return of low B12 symptoms and not feeling as good.

So I increase Levothyroxine back up, initially to 112mcg. Retesting after 8 weeks. That increase had stopped FT4 dropping, but hadn't risen at all. So increased Levothyroxine back to 125mcg

Typically my FT4 is back to 17-18 and FT3 around 6-6.3