Potency of T3 vs T4 medications

[goolarra]

I have read that T3 is "several times" more potent than T4, when taken for hypothyroidism.  Does anyone know specific numbers? range?  For example, if I wanted to replace 25mcg of T4 with T3, how much T3 would that be?

[Smilerdeb]

Good to see you AR !
He is my mentor and lifesaver lol.
I started low, went hyper then restarted low again on .25mcg so maybe this is the way to do it.Going up in .25mcg increments worked for me.
I am still only on .75mcg but my TSH went down to just over 2 in 11 days from 3.88 and I didnt go hyper either.
Changing dosage too fast  and deficiency in zinc, B12 and D were the reasons (I believe) that I couldnt get my TSH down.
All in all...I just sit back and wait now.
I have some crappy days but I have more good days than crappy now.
My levels are all within reference range but my TSH could come down a fraction more.
As AR said, if your Free T's are low and your TSH high then you will need to increase slowly because of tachycardia.
I have taken Inderal once or twice because of tachycardia but not on a regular basis like I was just after RAI.
When it comes to thyroid issues...there is no fast solution :(
But being positive (yes it is hard) and knowing your symptoms makes it a lot easier.

[goolarra]

Hello, again!

You are the voice of reason, but much more charitable than I, especially when evaluating doctors!  As I said, my health insurance does what vacuum cleaners do best, so I can't afford to waste a lot of health care dollars.  I did ask the correct question when starting T4:  will this effect my WPW?  She assured me it wouldn't, unless I went hyper - perhaps the little red light bulb in the brain wasn't engaged that day (that T4 causes a lot of people, even those who've never had it before to have tachy, seems to be pretty well documented in the literature/personal experience of patients).  Being very naive at the time, I believed her completely.  After all, I reasoned, it's not rocket science...wrong!  Then she put me on T3 after just 6 months on T4, and wanted to do it on a 1:1 ratio.  I'm afraid the credibility is gone.  She also got kind of nasty when I went to an electrophysiologist for the beat-blocker.

So, I am in the process of finding a new doc...I dread this...always hate having to "break in" a new one.

I know you've suggested before "starting over".  Do you think I've, in effect, already done this by backing off from 88 to 25 and then very slowly working up to 69?  Or do you think I really have to back off all the way to zero, which is scary?

Thanks for your info.
AJ

[goolarra]

Thanks for all your input.  I'm working on the new doc - I may post a question about doctor recommendations in Central Oregon, or anywhere in Oregon for that matter.  Boonies are not good for this kind of thing.

[AR-10]

The potency of T3 varies from person to person and is anywhere from 3 to 8 times as potent as T4.

Starting any patient on T3 before knowing how they will respond to T4 treatment is not standard practice and it is not wise.

Goolarra has test results showing her hormone levels are very low. Even though she has no symptoms, she pretty much has no T3, either.

Starting her at 88mcg may have been a mistake. Starting her at 25mcg and working up may have worked better.

Most patients don't have a problem with tolerating levothroxine, and "baby steps" are not needed. some peope DO have problems, and for those people stopping a large dose and starting over with a small dose and working up is the only way to do it.

It's not really the doctor's fault, if that is the case. Most people can start taking 100mcg of med and feel better for it (if it is the dose they need) right away, without having to spend months on end working up to that strength.

Unfortunately, goolarra seems to be one of the people who should have started small and worked up.

[bizwiz12751]

Actually, she should have started you on 25 mcg of T4 and introduced 5 mcg of T3 twice a day to see how you react. T3 gets absorped right away so it carries quite a punch. I feel my blood pressure rise a bit every time I take one so I know that it carries a punch. I would probably try to change the doctor even if it's hard to find one. Sometimes it's better to take the time to travel since the medicine for the thyroid is already frustrating enough. Good luck.

[pep88]

I've been in your neck of the woods on business (b4 child) several times, as I live in Seattle.  And I do understand what that rural area is like.  As I recall the company flew me in via private (extremely SMALL) plane.  Not sure how you could get help in your situtation.  The only thing I would suggest is to read up a TON on the internet and print some articles for your endo.  I guess you'll both just have to learn together.

[goolarra]

Very true.  She does know about the conversion, but actually sat there and said that the T4 would not cause a problem with the tachy unless I went all the way over to being hyper.  Even confronted with the evidence, she looks at me like I'm out of my mind.  The 88 mcg she started me out on says it all...she has no clue what she's doing.  If she had started me at 12.5 to 25 mcg, I might have had an entirely different experience.  Meanwhile, I've paid the price, not her.  She has one mantra - low FT3 and FT4, high TSH - "need more thyroid" (actual quote).  I'm working on it!

[Smilerdeb]

Doesnt the current PCP know that T4 converts into T3 ????
T3 causes heart palps and fibrillation???
Thats the problem I think....WE educate our Doctors as they know very little about the Thyroid.
Sad to say :(

[goolarra]

I'm in the process of finding a new doc...excruciating  process.  Complicated by the fact that I live in rural Oregon.  Four PCPs in our little town, two married (to each other - net 3 PCPs).  Three endos in the "big" town 20 miles from here.  Next market 125 miles away over "the pass", which becomes the impasse once the snow flies (which it already has)!

I agree...treat ME, not the numbers...easier said than done.  Current doc went absolutely ballistic at the mention of Armour, although I've heard that T1 or T2 (can't remember which), which are in Amour, have a lot to do with heart regulation (on the positive side).

Current PCP suggested T3, seems to think the tachy has nothing to do with the T4.  Assured me I'd have to be hyper before it would cause me a problem.  Yeah, right.  I agree she is NUTS, but no one else seems to think so, except you and me.

I'm sending questionnaires to the local endos...don't know who else to pursue...very frustrating.

[Smilerdeb]

T3 wont lower the TSH but will bring on Thyroid storm if it is increased in your situation.
I would be starting to look at finding a Doc who knows what hes talking about.
My thyroid is dead and non functioning and when I went hypo , for me it was hell.
But my Free T's were also 'down' too.
Not many Doctors will entertain T3 with someone with heart conditions, especially with a history of Supraventricular Fibrillations.
Thats madness.

[pep88]

T3 will only make your heart palps worse not better.  If all your hypo symptoms are gone your doc is NUTS for force feeding you meds (especially T3) to just to appease him/herself and make you an official TSH poster child!  Find a new doc.

[goolarra]

I agree about the variables, which is why I really want to change only one thing at a time to isolate its effect.  That's why I wanted to know the potency of T3 vs T4.  Control the overall dose at pre-change levels, then there's only one thing responsible for any changes in symptoms.

Please see comments above for more on my situation.

I  agree it takes a lot of time, and we're all different.  As I said above, I feel like I'm the only one in my situation.  Labs look like I should have raging hypo symptoms, but I don't.  Most people complain they have absolutely "normal" labs, but raging symptoms.

I'm beginning to feel like a freak!

[goolarra]

I'm sorry to have created a misimpression - I have a complete thyroid, haven't had RAI, been on T4 for almost 11 months, just garden variety hypo.  My problem is that whenever I increase T4, the tachy goes nuts and I have to increase the beta-blocker, which in turn makes me need more T4 (vicious circle).  My TSH is very high, FT3 and FT4 very low normal, and my PCP wants me to keep increasing.  Meanwhile, ALL my hypo symptoms have gone.  I feel great.  The only reason I have for increasing T4 is to appease my PCP and get my labs "right". I pay with the tachy.  I hear NOTHING about people whose labs make them look sick, sick, sick, but who feel just fine.  Am I really the only one?  I suspect that people with similar labs to mine are out there walking around, feeling just fine, which is why they haven't been diagnosed, and I wonder if there is anything to diagnose considering the lack of symptoms

Anyway, the heart issues are a pain in the butt, aren't they?  I don't even know if I can expect them to eventually go away.  They seem to have settled in permanently.

Thanks so much for your comments.  

It's really interesting...here they tell you that you SHOULD take your T4 on the day of your blood work...more contradictions..

[Smilerdeb]

Very true statement.

[pep88]

I think it's mute point to ask how much T3 should be taken in relationship to T4.   There are SO many variables in that equation everyone.  For instance, Do you have a thyroid or not? How well are you PERSONALLY able to convert T4 into T3?  Are you really having a problem with conversion?  How quickly do you metabolize T3?  

I personally started out post TT with a high dose of T3 in relationship to my T4.  And my body just simply wasn't able to handle it.  I went to T4 only to see how well I could convert my own T4 into T3.  I'd never been on replacement meds prior to my TT for cancer.  I didn't feel nearly as well on T4 only, and just knew I'd not due well on T4 only for the rest of my life. I switched back but at a much higher T4 to T3 ratio.  It works well for me.  But I can only take the T3 first thing in the morning unless I want to be up all night.  *I* metabolize T3 very slowly.  I know others who can take large doses both in the morning and in the evening, not feel any adverse effects and then go straight to sleep.  It's simply a function of your body and it's ability to handle T3 as well as how well it converts it's own T4 into T3.  

I seriously don't think there is one carte blanche answer for everyone.  And I'm a poster child for any and every combo of synthetic T4/T3 med combo.  It takes time and experimentation to find YOUR right dosage.

[Smilerdeb]

I too have heart problems with Bradycardia and Tachycardia resulting from being born with a heart murmur (born with Rheumatic Fever).It was classified as 'innocent' until I was diagnosed with Graves...and when Hyper my Inderal was increased to a high dose.
I also have Mitral Valve and Tricuspid Valve Prolapse and Regurgitation which is evaluated every year by a Cardiologist...once again only found when I was diagnosed with Graves but prior to that...never picked up.
AJ please dont mess with T3 at the moment.
Give your body time to 'heal' from the RAI.
Take each day as it comes on the Synthroid (I am on Eutroxsig here in Australia which is the proper Thyroxin) and slowly bit by bit, your levels should come under control and the heart episodes subside.
I dont have the fast heartrate anymore, I feel good and my TSH is coming down to nearly 2.0.
Yes its a pain in the butt...yes up until 3 weeks ago I felt like giving up on it all but TIME is the secret to success here.
As hard as it is to be patient, that is what is needed to get to a stage where you can function normally.
Please dont even think about T3 until you have been on the Synthroid at least 6-9 months.
They say it takes a good 12 months for levels to even out.
I was hypo 5 weeks after RAI even on the lowest dose of RAI.The Endo kept demanding 25mlc of RAI but I stood my ground and had 8mlc. I hate to think what wouldve happened if I did have 25mlc as I was T3 toxycosis when I had RAI.
Get your vitamins checked with your bloods......
Selenium, D, B12, Calcium, D, Zinc.
and slowly bit by bit you will know if you need an increase in Synthroid by your symptoms and bloods. Do it in .25mcg increments under your Doctors advise and when you go for bloods , make sure you havent taken any Synthroid that morning.
I go at 8am to get a clear even reading.
It will work out ok.....and it does get easier, I promise you.
And it wasnt my Doc who knew how to do it...it was me.
I basically educated him and we work together now and it is great.
As for the Endo, I saw her before RAI and after RAI then walked out on her as she wanted to increase my thyroxin when bloods showed T3 toxycosis !
I never went back to her.
My primary Doc works with me now and he gives me labs sheets so I can get my bloods done then call him in regards to dosage.
RAI is not an 'easy fix'....it is just as hard as getting your levels right as it was before RAI.
I had weekly appointments with my Doctor to make sure I didnt go Hyper (which I did but was picked up quick).My appointments are 3-4 weekly now.
It is a long slow road but if you tread carefully, you will get there.

[goolarra]

We have a lot in common.

I'm also drug sensitive.  I have Wolfe-Parkinson-White syndrome, a congenital heart defect that causes tachycardia - super ventricular tachycardia (PSVT) as opposed to AFib.  The  WPW was totally under control without meds before I started taking T4.  PCP put me on 88mcg  T4 to start, and then did the fun begin!

I had to keep backing off, eventually down to 25mcg, and still the tachy raged.  So now I'm on a beta-blocker to counter that.  You're lucky your doc knew enought to do the baby steps.  It sounds like you're getting everything under control.
AJ

[goolarra]

I'm not building the pyramid, yet...I combine and split when my dose changes.  Let's see...the blue ones are...hmmmmm.  

Isn't it amazing how "(wo)men of science" are so happy to just toss the scientific method out the door once they're in a clinical rather than a lab setting.

Oh yeah, my doc also said that they only give 5mcg to babies!!!
AJ

[bizwiz12751]

Unfortunately, thyroid medicine causes great frustrations for the patient. It takes so long to level out and I've seen many people do more harm by trying to make too many dose switches and not give the medicine time to work through the body. That's a great point, many times vitamin deficiencies do act as thyroid symptoms. So, although it's frustrating, hang in there and it will work out.

[Smilerdeb]

I totally agree with you in regards to not taking T3 on its own because of its potency.
I suffer with 'drug sensitivity' so at present T3 is not an option for me.
I have had to 'wait the distance' and it has finally paid off. My TSH has gone down from 3.8 to 2.3 in 11 days without making the Free T's go too high. I have to increase my T4 in .25mcg increments too as I suffered with Atrial Fibrillation prior to Rai (Graves and Hyperthyroidism).
I am currently on .75mcg T4 and expect another increase to .88mcg within the next 2 weeks.
As they say....baby steps all the way.
My Doctor tried increasing my T4 in .50mcg increases and I went hyper so had to start from scratch all over again.
Its been 5 months post RAI and I am normal Free T's and TSH is coming down doing it 'slowly.
There was a question at one stage where it was thought I had conversion problems but  it seemed to even itself out slowly.
I feel great now, especially since I had my vitamin levels checked and found to be deficient in Zinc, Vit. D, B12.and now take these supplements.
Magnesium took away the aches in the legs and burning of the feet that a lot suffer with Graves Disease.

[bizwiz12751]

Absolutely correct! It's best to add T3 as an overall total, wait 6 weeks, take blood work to check for free T3 and free T4 and adjusting the dosage accordingly. It's been 2.5 years since my TT and I've finally been on the one dose for longer than 3 months. I can build a pyramid with the left over medicine bottles of T4 and T3 medicine from experimenting so much with the dosages. So, finally, it looks like 175 mcg of Synthroid (taken @ 5:30 am) and 5 mcg of Cytomel at 7:30 am and another 5 mcg of Cytomel at 1:30 pm is what's keeping me sane. Everybody's different and you definitely have to use your common sense when you are talking to the doctors.

[bizwiz12751]

The dosage is determined depending on a patient and the symptoms. However, the medicine potency itself, which is what goolarra was asking, usually T3 is 2 or 2.5 times stronger than T4. For example, 25 mcg Cytomel would equal approximately 50 mcg of Synthroid. As I stated, T3 is immediately absorped so the dosage may have to be split in two or even three doses depending on symptoms and/or other medications. Many people have conversion problems with T4. I, personally, would never take T3 alone, but combined with T4 it certainly made me feel human again.


  

[goolarra]

Thanks.  I agree - I've heard T4/T3 ratio of 4:1 or sometimes 3:1, the latter to clear up brain fog.  Unfortunately, my current doctor (soon to be former) really doesn't seem to have any idea what's going on.  When I was taking 50 mcg T4, she suggested adding a "little" T3.  a couple of keystrokes later and she wanted to drop my T4 to 25 mcg and add 25mcg T3, with never any mention of splitting the dose.  I protested loudly, and she begrudgingly settled on 5mcg T3 and lowered the T4 to 25mcg.  It didn't work out (surprise, surprise).  I just feel that in making changes, it's really important to only change one variable at a time - if you introduce T3, then you should probably keep the "overall" dose of T3 + T4 about the same as what you were taking before adding the T3.  Then you see what the "new" variable is actually doing.  Thus, the question.  Thanks for reminding me about splitting the dose.  I'm working on questions for a new doc, and you just reminded me of one more.
AJ

[Smilerdeb]

I may be wrong but usually the dosage of T3 is determined by how much T4 is being taken.
Usually it is 80% T4 and 20% T3 and it is unadvisable to take T3 on its own.
T4 is absorbed in the bloodstream, goes to the liver which then converts it to T3.
Taking T3 on its own doesnt do this.
It doesnt stay in your system for long so you have 'highs' and 'lows' of medication.
If you are concerned, I would ask your Doctor.