T4 Conversion or not T4 conversion: I'm going to... - Thyroid UK

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T4 Conversion or not T4 conversion

GKeith
GKeith

I'm going to see my endo tomorrow. This is a guy who tests only TSH and FT3 & FT4. Luckily I also test with the VA and my GP. So, my question is: I've been taking T4 (again, after quitting for about 2 weeks, in August.) I take 50mcg of T4 and 30mcg of T3 but have recently been self dosing and am up to 75mcg of T4. I did this because the endo I have is part of a medical plan called “Capitation.” It is simply a plan that pays doctors (the insurance company) for prescribing less costly drugs, etc. A fiendish plan born only in the Land of the Free and the home of Donald J. Trump. Anyway, my TSH (taken a week ago) was 0.03, my FT4 was 0.7ng/dL -0.8-1.8 ng/dL, my FT3 was 3.1pg/mL -2.3-4.2pg/mL The test before that was taken a month previously in November but covered much more bloods: TSH--0.03, FT3---4.0 ---2.3-4.2 pg/mL FT4 0.5---- 0.8-1.8 ng/dL TT4: 3.5 ----4.9-10.5 mcg/dL TT3: 137--- 76-181 ng/dL T3 REVERSE: 9 ng/dL ---8-25 ng/dL FERRITIN: 42 ----20-380 ng/mL Vit.B12: 589---200-1100 pg/mL FOLATE: 20.2 ---2-20 ng/mL CORTISOL:18.2 ---10-20 mcg/dL

So, as you can see it appears to me that just as if your FT4 is at top of range and FT3 is at the bottom you're not converting well, if, as in my bloods, the FT4 is bottom of range and FT3 top of range you are converting your T4 to T3, as you should be. I am guessing at this because I understand most on this site appear to feel better when both levels are high. I feel very good at this time but that could change. Also, I have only been self-medicating T4 for the past 3 or 4 months. Anyone who has any knowledge or thoughts on this comment(s) welcome. Oh, and I'm going to ask him to up the T4 from 50 to 75mcg, something he'll love, almost as much as he hates giving me T3.

16 Replies
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"This is a guy who tests only TSH and FT3 & FT4" - many of us would bite your hand off, to have a Dr who measured more than TSH .........

"The FT4 is bottom of range and FT3 top of range (means) you are converting your T4 to T3, as you should be" - no, not really. Effective conversion of T4 to T3 does not result in depletion of T4, because in a well person or one who is optimally medicated, there should be a constancy in the supply of T4. It is when you supplement with some form of T3 that this changes the test result profile, often showing low or suppressed TSH and low FT4. This is because with the exogenous T3, the pituitary is no longer being prompted to produce TSH and therefore the thyroid isn't being prompted to make T4/T3 (depending on the existence and/or functionality of the thyroid, and adequacy of dosing, the degree to which this is happening, will vary of course). Some people may be fine with this lower level of FT4, others less so. Some people believe that they feel better with a slightly higher TSH too. Some people find that increasing T4 may have the effect of reducing FT3 & increasing RT3, the higher their FT3 rises, so dosing adjustments need to be done gradually.

GKeith
GKeith
in reply to MaisieGray

Well, in November I had my RT3 checked for the first time. Most endo's & GP's don't have a clue about it & even many that do, do not check it. Anyway it was very low. As close as I can figure RT3 is too much T4 waiting around to be converted. Anyway, I feel very good and probably have found my optimal amount, or very close to it, as my only hypo symptoms left are cold hands early in the morning and late at night, a dry right eye and itchy skin. My TSH has meant nothing to me ever since I started T3 and it went down to almost nothing and I felt like superman compared to how I had on T4 only for 26 years. As fr as increasing T4 causing FT3 to lower. On 50mcg, you have somewhat of a point because my FT3 was 4.0 pg/mL of 2.3-4.2 range and the one last week was 3.1, in high(er) range but not as high as 3 weeks ago. However, I will have to wait for that, as I have self-dosed to 75 mcg and will ask my endo to raise it because of the way I feel. I take 75 mcg T4 and 15mcg of T3 at midnight, then 10 mcg of T3 at 4-6 am and can actuyally feel my hands and feet go from cold to very warm, so...

I must say that I have been quite educated on the do'es & don'ts, the pluses and minuses of hypothyroid here and my already low estimation for the educated classes, the doctors, the specialists, and all their cohorts, has even fallen considerably. I have absolutely nothing against the educated classes,I have 3 years of college and a degree in pre-law myself & have a brother who earned a Phd. I am just terribly annoyed at their pretenses of authority over others and their haughty attitudes that everyone else is inferior to their intelligence. We are winners when we tell the truth & losers when we lie and a big problem we have here in the U.S.A. Is that the leader of our country is a bigger liar than Pinocchio.

MaisieGray
MaisieGray
in reply to GKeith

"RT3 is too much T4 waiting around to be converted".

Reverse T3 is a biologically inactive metabolite of thyroxine (T4) formed by selective deiodination. So the active thyroid hormone T3 is formed by removal of an iodine atom in the outer ring of T4, while rT3 is formed by removal of an iodine atom in the inner ring of T4.

The relative amounts of each are determined by the activity of the respective deiodinase enzymes, which are regulated by hormonal and nutritional factors and physiological conditions. So for instance, rT3 can be elevated in conditions associated with a reduction in the metabolic rate, such as extreme carbohydrate or calorie restriction, chronic heart failure, and non-thyroidal illness syndrome for instance. So you can have high rT3 when generally ill, or in times of chronic stress, or as a result of being in a chronic inflammatory state. In these cases, the rise in rT3 is a consequence, not a cause, of the alterations in intracellular thyroid hormone metabolism directed by the deiodinase enzymes; the relative activities of which are affected by the condition itself. So in general, rT3 has the effect of lowering the amount of active thyroid hormone T3, available to the cells.

GKeith
GKeith
in reply to MaisieGray

I get that and will be quite aware of it if the T3 lowers or not. Also I will be aware of the amount of iodine, iron, zinc & selenium in my blood. I'm trying to get all those checked but my endo won't do it so I'll have to get my GP to. The easiest way to get either one to write a blood test is the shortest writing but I'm not sure, for example how much a TIBC (total iron binding capacity) would cover besides iron because, from what I understand, selenium, zinc and iodine are just as important?

GKeith,

You will not get a true gauge of how well you are converting if you are medicating T3.

Also, considering how multifactorial T4-T3 conversion is, how minor your dose increment and your “recent” requiring a period of at least four - six weeks, it might be difficult to form an opinion with brevity.

I achieve-well being on low in-range thyroid hormone but considering other members in this forum, I appear to be in the minority.

Iron is key for T4-T3 conversion and your ferritin is low. Are you supplementing ?

Glad you are feeling good.

GKeith
GKeith
in reply to radd

Just gummy vitamin pills but it covers 100%, or more, of Vit. A, C, D, E, B-6, B-12 and Iodine, zinc, selenium Folic Acid & Pantothenic acid.

radd
radd
in reply to GKeith

No iron ? ..

GKeith
GKeith
in reply to radd

Nope. Funny too because I was slightly anameic when I was a kid. I just figure because I eat so much red meat, chicken and fish, not to mention I drink a 1/2 gallon of iced and hot tea with tablespoons of honey. If it's low next blood test I'll probably supplement some iron.

radd
radd
in reply to GKeith

GKeith,

Most of the iron that is stored in the body is bound to ferritin, which makes it a good marker for how much iron you have.

The ferritin reference range is always very wide but low ferritin can cause negative reactions such as palpitations in someone medicating thyroid hormone replacement.

But more importantly for you is that iron is absolute key for a healthy conversion level of T4-T3.

Also, it is unwise to supplement iodine when medicating thyroid hormone replacement as this already contains the correct amount we need.

GKeith
GKeith
in reply to radd

My endo thinks nothing of whether any blood test come in low or high, as long as it's: in range. BTW, what do you think of NDT?

radd
radd
in reply to GKeith

GKeith,

No, they usually don’t .... as long as it’s “in-range”.

What do I think of NDT ? ? ..... I medicate it successfully.

GKeith
GKeith
in reply to radd

If you don't mind me asking how much do you take and do you also take anything with it? Like extra T3 or ...

May Peace be upon you

radd
radd
in reply to GKeith

GKeith,

I have Hashi and absolutely no thyroid left. I medicate 1.5 grains of NDT. For me it was about getting everything else right and maintaining it.

Many members have found NDT difficult to introduce when suffering from low iron levels. It also gives you no flexibility re freedom to titivate T4/T3 amounts.

You are medicating a much larger ratio of T3/T4 than NDT would be giving you.

GKeith
GKeith
in reply to radd

I know & as long as I feel as if I'm close to obtaining my optimum level I will continue on that path. I will keep dosing T4/T3, while looking for the one that eradicates all, or most, symptoms. Now, if only I can actually find an endo who is also a human being with an actual heart and conscience, along with a little common sense?

Hi GK, Radd has explained very well how calculating your conversion rate is not too sensible if you are taking T3.

However... If you are curious how to do this at some point, this is how you do it:

You have FT4 = .7 ng/dL

and FT3 = 3.1 pg/mL

1) Since we want a ratio we must first get the units the same. Let's get FT4's ng/dL to FT3's pg/mL. There are easy conversion algorithms on the internet, just Google "ng/dL to pg/mL" and one pops up.

2) Your results: FT4 = .7 ng/dL = 7pg/mL

FT3 = 3.1 pg/mL (given)

3) Your ratio: FT4/FT3 = 7/3.1 = approximately 2.3

This is very low, you need to be in the order of 3 or 4. What the result says is that it only takes a little over 2 T4 molecules to generate 1 T3 molecule. You are running too hot - but then you are supplementing with T3 so you are not measuring your true body chemistry i.e. your conversion rate . But, like I said, if you are ever on levothyroxine alone, this is how you would do it. Just FYI humans run about 4:1 and pigs run about 3:1

You are speaking of T4 to T3 ratio's I take it. So, if I'm taking 75 mcg of T4 and 30 mcg of T3, I should be at 2/1/2 times of T4 to T3? The problem is that, at this time, I feel very good on 75 mcg of T4 and 30 mcg of T3. So ... I am ready, I think, to try NDT & see how I feel. I'd like to go back to taking just one pill, too. I've heard an awful lot of both good and bad about NDT but I'm still listening and have just written another post about this "problem?"

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