For my Free T labs, what are the conversion factors for US to international on FT4 and FT3?
Free t3 Conversion factor pg/mL to pmol/L is 1.5362
(multiply US value by 1.5362, or divide international value by 1.5362, to change one to other)
Free t4 Conversion factor ng/dL to pmol/L is 12.87
(multiply US value by 12.87, or divide International value by 12.87, to change one to other)
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What are the most common mistakes on switching from pure T4 to NDT after TT?
Common mistakes in switching over to NDT/DTE (Armour or similar) or T4/T3 combos
Cytomel, liothyronine = T3 (synthetic)
Levothyroxine, Synthroid, Tirosint = T4 (synthetic)
Armour, NP Thyroid = natural thyroid or NDT/DTE with both T4 and T3
1 Failure during switchover to reduce T4 dosage and give time for the FT4 to fall before starting Armour, or adding T3 (cytomel) to the reduced T4 dose. This is worse in cases where the FT4 is up at the top of range. It takes over a whole week for the FT4 to fall in half by not taking any (none), and often the FT4 is just way too high to start anything with T3 in it especially the amounts in NDT/DTE. If adding cytomel, it should generally be when the FT4 is moderate or light moderate, generally never near top of the FT4 range because it potentially causes many issues when added at above moderate FT4.
2 Failure of doctor to tell patient that T3/NDT is spread over the day, and that these are not once a day medication like Synthroid/Levo/T4.
3 Failure to get or doctor to prescribe appropriate doses of NDT and/or T3. This includes some really bad charts out there of what is the right NDT dose if going that way. About 60 to 70 mcg T4 is about 1 grain of NDT (60 or 65 mg depending on brand), not 100 mcg!
4 Failure of doctor or you to request monitoring the FT4
and FT3 once patient is on a combo or NDT, and still using TSH alone. One wants
a moderate FT4 and very good FT3. Here is an example of a person that likely
will have fewer issues, USA lab type values
Free t4: 1.09 ng/dL
Free t3: 3.72 pg/mL
Reverse T3: 10.8 ng/dl
5 Not considering that fillers can be causing some of your issues. Pill fillers combined with your metabolism all in a pill can cause various issues for many people. Acacia/ other gums, sugar alcohols (end in “ol”), talc, cornstarch are common issues for people.
6 Not checking for other issues, optimizing vitamin levels, or dealing with anemia even if a borderline anemia. One really wants the ferritin say 60 or 70 or so, not 12 or 18 and certainly not 250, plus CBC showing no issues like anemia or borderline anemia. Vitamin D a good lab is say 65, not 20.
7 Not timing labs. Free t3 is time sensitive, you can’t take NDT or T3 and go out and do a lab an hour later. We often mention on the list 8 hours after half (afternoon lab), or 16 hours after second half (an AM lab)
8 Not bringing FT4 up to reasonable if Armour/NDT doesn’t do the job and you have given it time and tried increases. Some people need a small amount of T4 to feel right and get the FT4 up to a more reasonable level, just some never think of this and lag not doing great for sometime before figuring this out.
9 Not doing some of your own work and documenting it so you, your doctors, and those you communicate with can understand what you have tried. Only you can determine if you are feeling well/normal or 100%. It can take some months or years to work out what is working and not working. Only you can do it with a doctor being flexible to your requests. Doctors these days often have MBA’s pushing them for productivity, like they are real estate agents or factory workers. You need a flexible one but you need to do a lot of work yourself, documenting problems, documenting successes, how you take your meds, how many hours since meds was the lab, What were the Free's, What were the issues and problems, HYPO/HYPER symptoms, etc.
10. Failure to examine Methylene tetrahydrofolate reductase (MTHFR) and looking to reduce homocysteine. If your homocysteine tests above 10 (USA lab), it is potentially likely you have some issues caused by MTHFR genetics. Most people should test 6 to 10 area on homocysteine. It is very common to have thyroid disorders with MTHFR genetics. The easiest cure is to stop buying/eating food with folic acid, and using Betaine HCL w/pepsin.
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How do I add cytomel (T3) to my T4 prescription?
Note that people needing larger amount of T3 because their FT3 tests very low, often need to bring the amounts up slowly over time.
Depends on where your TSH and Free t4 currently are.
a) Condition: Goal is to keep things roughly the same TSH.
In this case reduce t4 by 4 mcg for each 1 mcg of T3 added. That is rough, and people vary all over but it is always easy to add T4 back so I would reduce the T4 prescription by 4 mcg for each 1 mcg T3 added first. For safety sake, if the TSH is already highly suppressed on T4 meds you should remove the T4 well ahead, such as a week or more before adding the T3 you plan on trying.
b) Condition: Goal is to bring TSH down.
If your FT4 is moderate/mid level and TSH not suppressed you likely won’t need to reduce the amount of T4 you take or not as much.
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Do I switch immediately from pure T4 (like synthroid) to NDT the next day?
When you switch from pure T4, most people start with a Free t4 level somewhere of FT4 1.4 to 2.0. Generally all these people must go off T4 medication for up to one full week before starting anything like Armour or Nature-throid that has T3 in it.
T3 is super powerful and has an immediate effect basically within an hour of taking it. So if you add it to a higher level of FT4 you get hyper symptoms immediately after taking on a switch. This is why you must wait up to a whole week for some people to start, but it depends on what the FT4 is.
You want a very moderate FT4 to start the NDT, so you generally have to wait some days to a week to drop the FT4 down before starting as pure T4 usually leaves the FT4 too high to start NDT.
Roughly speaking you want a FT4 of about 1.2 to start NDT. 1.4 is ok for some, for cardiac risk 1.0 is suggested. There is wide variation in people, but for best experience it is suggested to bring it down first, then start the NDT.
Gauge where you are based on a FT4 before starting NDT. If your FT4 1.8 you can't switch the next day. The higher it is the more you need to wait before you start basically.
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Does T3 change TSH?
Yes. T3 is also much more powerful than T4 per mcg taken. However, the TSH effect of T3 varies widely by person and is specific to you, but no matter what the case is for you, the T3 will be vastly more powerful at suppressing TSH than T4.
The majority of people will be somewhere in the area of 1 mcg T3 has the same effect as 2 to 4 mcg T4. A tighter view would say many are around 2.5 to 3.5, in T3 being that times more powerful than T4 at suppressing TSH. Official statements usually say T3 is 4 times more powerful but this is very conservative view to accommodate the high possible side effects and most people probably run in the 2.5 to 3.5 effect area.
You won't know till you try for yourself where you are.
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How do I take natural desiccated thyroid (NDT) or long term cytomel?
Almost everyone divides the daily dose in two and takes half of the daily dose first thing in AM and half in afternoon, or a wide set of variations of this. That is to help with T3 run-out. If you take it once a day your alertness levels may swing too much, and at same time the T3 gets too high early and runs out later in afternoon. This can cause side effects of too high a T3 early in the day (HYPER), and T3 run out feel late in the day (HYPO). There are a few who have a cortisol cycle such that they can't take it later in day and end up once a day, but almost everyone else from the start takes it at least two times a day.
Generally once a day DTE/NDT is associated with light or very light doses.
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What are the equivalent amounts to switch from T4 only to NDT (middle of a bell curve)?
With NDT we use the word "grain". 1 grain of NDT has 38 mcg T4 and 9 mcg T3 in the USA. The listed mg of a grain depends on brand such as Armour or Nature-Throid. A grain can be 60mg or 65 mg (which is not an amount of T4 or T3) and again depends on the brand as to the mg but not the amount of T4 and T3.
This chart is aimed at the kind of middle of the curve group where 1 mcg of T3 is about like 2.5 to 3.5 mcg of T4. It does not represent all people, just kind of the middle of the bell curve. Amounts to swap are dependent upon each individual and how T3 works on you. With that in mind, the middle of the bell curve group suggests swaps having 1 grain equal about 60 to 70 mcg T4. You very well may need more or less if you take very large amounts, or very low amounts, of T4 to work for you and you are of normal weight:
100 mcg pure T4 calculated 1.4 to 1.7 grains: Low possible 1.25 grains,
average 1.5 to 1.75 grains, high possible 2.0/2.25 grains
125 mcg pure T4 calculated 1.75 to 2.1 grains: Low possible 1.5 grains,
average 1.75 to 2.0 grains, high possible 2.25/2.5 grains
150 mcg pure T4 calculated 2.1 to 2.5 grains: Low possible 2.0 grains, average 2.0 to 2.75 grains, high possible 3.0/3.25 grains
175 mcg pure T4 calculated 2.5 to 3 grains: Low possible 2.25 grains, average 2.5 to 3.0 grains, high possible 3.5 grains
200 mcg pure T4 calculated 2.85 to 3.3 grains: Low possible 2.5 grains, average 3.0 to 3.5 grains, high possible 4/4.5 grains
Once again, you split this in two, taking half first thing AM and half in the afternoon or some variation like in thirds, etc.
Those who do not absorb synthroid that well and thus take larger amounts are further out on a bell curve and would have differing numbers than above. For them 1 mcg of T3 might have the effect closer to 5 or 6 mcg of T4. This would be very possible but is less likely. So keep in mind the chart above is middle of the curve and if you are taking very large amounts of synthroid with a normal weight the chart above may not apply to you but it may be possible to adapt it knowing you take double the amount of synthroid than others your weight for example.
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But the charts give a different equivalent for NDT, why is that?
Equivalency charts are designed around a highly conservative view that the highest possible effect should be listed in equivalents in case of side effects, trouble is that can raise TSH and leave you feeling lousy. Because of that basically there are charts out there giving incorrect amount of NDT to replace pure T4 even by conservative measures. These charts say 1 grain has the same effect as 100 mcg T4. This is just not the case. 1 grain of natural thyroid has only 38 mcg T4 and 9 mcg T3. This cannot have the same effect as pure 100 mcg T4.
From the calculations below you can see that for most people 1 grain of natural thyroid (USA only) has the effect of somewhere in the 60 to 70 mcg area of straight T4 only.
38 + [9x (varies by person but try 2.5)] = 38 + 22.5 = 60.5 T4 equivalent in my case because 1 mcg T3 has the same effect for me as 2.5 mcg T4.
38 + [9x (varies by person but try 3.5)] = 38 + 31.5 = 69.5 T4 equivalent in a person where 1 mcg T3 has the same effect as 3.5 mcg T4.
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How about ERFA (Canadian NDT)?
60 mg ERFA might have the effect of roughly only 55 to 63 mcg of straight T4. Varies widely by person, best ballpark is to use 2.5 to 3.5 maybe as much as 4 as multiplier on each mcg of T3 but it can vary from that and is individual.
In each Erfa 60 mg, there is 35 mcg. of T4 and 8 mcg of T3. If T3 for you specifically has the effect of 3 times T4, then use simple math:
35 + 8x3 = 59 mcg straight T4
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Does T3 or NDT use swing TSH around with lots of daily variation as I was told it will and I need my TSH suppressed due to thyroid cancer?
No. You can get what is called T3 run-out where the T3 gives a high alertness level after you take it and this often will fade as one gets to the afternoon, but the TSH does not change that quickly. Most people take T3 or NDT two times a day and it is not uncommon to forget, missing multiple or even a single T3 dose. This can cause the TSH to change a very small amount. If you are the kind of person that will forget taking afternoon T3 or NDT often you may get some small variations.
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I have high risk thyroid cancer and want to switch over to pure NDT but not let TSH rise, any way to be sure since charts are not the best conversion?
Monitor your Free t4 during switchover weekly and never let the Free t4 fall below say 1.0 US (which is 12.87 in international units) maybe even 1.1. If it is falling and looks like it is about to go under, increase the dose.
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I switched to NDT for my T3, can this change my Thyrogobulin (cancer marker)?
For the VAST majority of people: The stomach digests the Tg and breaks it down to proteins.
For a few of us, we have another likely issue, low stomach acid. Animal based thyroid hormones do contain thyroglobulin (Tg). In the case of low stomach acid, Tg might make it past the digestive system to the bloodstream. Tg is the lab based cancer marker used for checking for cancer recurrence after TT, and a rising Tg (at similar TSH) is indicative of cancer recurrence. Probably very very few people get a rise in Tg from natural thyroid. I have gotten that when my homocysteine is high indicating an MTHFR issue and low stomach acid. There are no studies that I know of on this. See the MTHFR info later in the blog or start yourself on Betaine w/pepsin
If you really need or want to take all possible effects of NDT out of the system, swap in an equal amount of T4 and T3 for two weeks before Tg labs. The mean half life of Thyroglobulin in the bloodstream is 65 hours. Taking away 5 half lives comes out around 13 to 14 days actually. Five half lives is sufficient to get it all the Tg out of the system from a technical perspective.
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I plan on starting NDT or cytomel and want to know if there are side effects from too high a FT3?
It depends on where the TSH and FT4 are as to the symptoms you may get.
If you take NDT or cytomel and your FT4 is toward the top of range (or over range) and you push the FT3 up till it is over range people often get too fast a GI, stomach irritability, anxiety, and other various hyper symptoms.
This is why you want to moderate the FT4 to take T3 and be sure you don’t take all your daily dose of NDT or T3 all at once.
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Any tips for taking NDT?
A kind of default is to split and take half early AM and half in the afternoon. There are some who need less in AM and some who need less in PM, so find what works for you.
Avoid calcium, iron, and fiber near time of taking.
Avoid food if you can for an hour before and after.
If you get a positive Thyrogobulin (positive Tg or cancer marker) from it, check the MTHFR information below.
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Can I take cytomel/NDT with food?
Sometimes cytomel or NDT is taken with food by some people. So the food issue is complex. Basically yes you can take it with light food in some circumstances.... That varies all over and is person specific.
A few people can't take it with food at all or it does not absorb.
Other people do take T3 with light food to slow down the absorption and T3 usage. This is hard to understand until you understand what T3 run-out is, but taking it with food slows that down sometimes for some people. Taking it on an empty stomach and sometimes it gets "used up" too quickly or you are subject to T3 run-out, get tired, etc. Taking it all at once or too much at once in the day and it can sometimes spike the T3 levels up too high, basically taking it with light food can slow this down for some people.
So the answer is all over.
Just keep in mind once on any T3 for the long term, that Free t testing has to be done much more carefully timed than before being on anything with T3.
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Does T3 help me lose weight?
Some causes of weight gain after thyroidectomy:
* Higher FT4 causes excess hunger with low satiety for many people, thus we gain weight.
* Low FT3. This is metabolic shut down territory. Body stops expending and goes into a kind of conservation mode, thus we gain weight.
Also but much rarer would be very low FT4, or very high FT3. Make sure you get all your lab reports so you know your numbers.
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When I add NDT/T3 to my regimen the TSH is so suppressed, why is this?
Human evolution never involved adaptation to significant exogenous T3 or T4. There is no guarantee the pituitary gland works exactly linearly correct at high doses of thyroid medication associated with post thyroidectomy patients, and particularly so for those that include T3.
The pituitary is a feedback control system that wasn’t really designed around people doing thyroid cancer recurrence prevention and may not normally operate under these conditions.
The pituitary makes its own T3 supply from T4 via direct conversion for its own use though it measures the total thyroid hormone levels in the bloodstream it does not depend on the blood T3 levels apparently since it can convert its own supply. This often results in peripheral signs of hypothyroidism such as skin or hair issue even though TSH is suppressed.
Reverse T3 (rT3) counts against TSH yet supplies no benefit since even rT3 is a hormone that is measured as part of the total hormone level by the pituitary
Benign pituitary adenomas are not uncommon and make the TSH a poor indicator.
In general the worse a T4 to T3 converter you are the less reliable your TSH reading may actually be.
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My doctor uses Total T3, what about that?
The reason your doctor uses Total T3 is to take the daily variability out of the picture to some degree. Using Free t3 one has to time things well or the results get easily skewed, total T3 is less susceptible to this happening.
The trouble with Total T3 is it includes bound, free, and reverse all combined to a grand total. Yet some of those are bad and some are good. So a total T3 can include bad things.
I really don't see why it is so hard for a doctor to say they like seeing what results are at (you and doctors choice say:) 8,16, 24 hours, or whatever X hours after taking meds such that they would rather order a test that gives not as useful information. It is pretty easy to tell a patient take your meds like you always do but I am used to Free t levels at X hours so I want you to do a lab at that time. Not so hard really, but many doctors don't trust patients to time it right and would like to take that out of the picture.
Free t3 gives a clear picture of where you are, it is really the thing to work off over time. When it is low you do badly.
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I took T3 (or natural thyroid) and got no reaction, what are the possibilities of what is going on?
Depending on your Free t3 level when you started, you might not be on enough T3. However, If you do not get much of any response from T3 at all and your symptoms persist this is a classic indication of a reverse T3 issue. Reverse t3 blocks T3 receptors in the body, thus making it hard to feel the effects of T3 initially. Reverse t3 can be caused by low ferritin (storage iron) as most frequent cause, cortisol, stress, and other factors. Make sure if you order iron tests that ferritin is tested and not just serum iron. Unless cortisol is well tested you don't know if high or low, so a must that you not treat either way unless certain cortisol is running high or low.
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I took T3 and got too much a reaction, what are the possibilities?
1) You added T3 at way too high a FT4 for you. Everyone varies, but if you are a reaction kind of person you need to take FT4 down to below 1.2 or 1.1, then try again adding T3.
2) a side condition like PCOS, or any other sex hormone issue can dramatically change the thyroid medications effect. There is nothing worse for a woman than wrong testosterone levels, these can cause many issues. For a man there is nothing worse than wrong estrogen levels, these can cause many issues not the least or which is a rising PSA.
3) You started with too much T3, such as day one 25 mcg.
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Does T3 cause a-fib, irregular rhythm and heart rate problems?
Generally to add T3 if you are a person subject to cardiac issues you should bring your Free t4 to 1.0 (US labs) before starting T3 or NDT. Occasional people may need to bring this level down even more. Adding T3 or NDT at higher FT4 is often the problem.
Too much thyroid hormone medication indicated by a high Free t4 (common) or way high Free t3 (very rare) might cause you to get a-fib, irregular rhythm and heart rate increases.
T3 has a fairly immediate effect and should be done with a fair amount of care. T4 is fairly slow to act, T3 changes things almost immediately. But either can be in excess. Always check your Free t4 first and look at that as a potential cause.
Some people find a balanced Free t scenario less likely to cause any of these issues than the typical high Free t4 scenario many are directed to post TT. Moderate FT4 and good FT3 are both in range, Unfortunately high Free t4 is often ignored by physicians.
Another major factor on these issues is cortisol levels (adrenal hormone). People with low or high cortisol levels, even if only subclinically low or high, are more subject to irregular rhythm and heart rate problems. Correcting cortisol levels can often help for those with these issues.
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I got a prescription for 50 mcg T3, I want to start this right away with my full course of T4, should I just jump right into taking the 50 mcg cytomel?
It is VERY uncommon to be prescribed 50 mcg cytomel. If you were prescribed 50 mcg cytomel just be sure you have carefully gone over all your physicians reasons for prescribing such a large quantity and that you fully understand what the plan is in detail. Taking large quantities of cytomel is VERY rare outside of certain special circumstances, so be sure there is full communication about why you need this large quantity, how you should proceed in taking this kind of large quantity of T3, what the potential side effects might be because they can be severe or even potentially deadly at this high a dose. Experience says those who must take larger amounts know and can describe to others the reasons they are prescribed a very large dose of T3.
There have been cases of prescription error, mistakes, miscommunications, insurance issues where only high doses are in approvals for RAI uses and high doses are prescribed accidently because of the insurance approval system listing the RAI dose, and numerous other problems involving large prescriptions of cytomel.
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Are there really any differences with people who have a thyroid and also take replacement hormones?
Summary in comparison to those who have thyroids but also take replacement hormones:
1) Thyroglobulin as most important issue, we must always concern ourselves with it.
2) Observational: Need for lower Free t4 generally speaking than those who have thyroid even if they are taking lots of replacement hormones as well. E.G potential lower range on Free t4 needed post TT.
3) Observational: We seem to magnify and get hyperthyroid symptoms more so than those with thyroids. Our testing and symptom observations have to center just as equally on hyperthyroid symptoms and levels, as they do on hypothyroid symptoms such as connected to low Free t3. We need to check both sides, hyper and hypo to do really well.
We have all read there are no differences but there are some. Many people try to act like one size fits all but it tends not to work too well. We have cancer and this is really different. We have to worry about Thyroglobulin (the cancer marker) and this can be a large issue if we have almost any risk for cancer recurrence. This is really important, and there are answers about Tg even if you take NDT. But Tg levels and what they mean should be understood and does differ from a person without thyroid cancer who is taking replacement hormones.
Unfortunately those of us without a thyroid almost always tolerate lower Free t4 than somebody with a thyroid. This is purely observational but seems very valid. Somehow the body is able to tolerate higher Free t4 levels when you have a thyroid even though that person's thyroid isn't really doing much if they are taking a fair amount of replacement hormone. The body gives some additional accommodation somehow if you have a thyroid. While there is large variation in people almost universally the recommendations and comfort levels without symptoms people have on levels of Free t4 will be lower without a thyroid. Large numbers of us have found this as a significant difference to those who have thyroids but are taking replacement hormones. This is kind of like saying the Free t4 range probably is lower for those after a thyroidectomy. Many of us think it should end at 1.5 (US level) after a thyroidectomy. Many still having a thyroid but taking replacement hormones find comfort and no issues at levels much higher than this.
Another observation is we are much more susceptible to hyperthyroidism symptoms without a thyroid. We can get a wide array of hyperthyroid symptoms that are just as bad as the hypothyroid symptoms, but we feel them quicker. Generally speaking we magnify the hyperthyroid symptoms without a thyroid. Common symptoms of hyperthyroidism include: anxiety, GI irritability and moving too fast, mood changes and swings, irritability or a short temper, headache and migraine, excess hunger and more. Those with thyroids but taking replacement hormones can often get away with little hyperthyroid symptoms and almost no concern for them in their lab testing. We generally must concern ourselves with levels that get too high on Free t4 and Free t3. Our measurements must focus hyperthyroid symptoms too.
So concern yourself and familiarize yourself with hyperthyroid symptoms way more than a person with identical numbers but who has a thyroid and is taking replacement hormones. This is why we pay attention to the hyper side just as much as the hypo side (like low free t3) and our testing and labs reflect that concern. There will be a few who never experience hyperthyroid symptoms at any number, just don't count on you being in that group if you have thyroid cancer and no longer have a thyroid. Too often the story surfaces of years of hyperthyroid symptoms disappearing after a dose reduction. That story is heard often. We do seem to differ from regular hypothyroid patients taking replacement hormones.
