Experiences with LevoT

[Guest guest]

I have been having some problems recently, after doing very well on levoT for 2

months. Iam still ironing out these problems. but i think the reason for my

problems has been not taking enough of the hormone.

I have a few questions to ask other folk on using LevoT:

For some reason i feel more frighten using this tablet than armour and i think

it is to do with the doctors reluctance to give you too much. With armour you

would simply keep going up until you hit your sweet spot. Should the same happen

with levoT?

What is a normal dose on T4 only. the NHS seems to think 150 is a high dose and

would prefer most people stay around 100. i have seen some stats from the nhs

(on here i think) and it seems most people are on around 100-150.

The thing is when you use natural hormones everyone seems to say 3 grains is

about the optimum (give and take a bit) and so this would equate to 300mgs on T4

only treatment. When i was on 2 grains i was doing very well and i have

recently increased T4 from 150 to 200mgs and i feel a lot better. i actually

think my correct dose could well be around 225, but i am waiting to see how i do

on 200 for 3 weeks first.

it would be good to get confirmation of my thoughts from some more experienced

users.

[Guest guest]

What is a normal dose on T4 only. the NHS seems to think 150 is a high dose and would prefer most people stay around 100. i have seen some stats from the nhs (on here i think) and it seems most people are on around 100-150.

---------

I went up to 250 generic T4 (levothyroxine) and still had lots of symptoms.

I then went on a combo of generic levothyroxine and Cytomel/Cynomel, and went down to 137.5 of T4 and worked my way up to 37.5 of T3. Some of my symptoms resolved themselves, but I never felt 100 percent.

I now am optimized on five grains of old Armour/Naturethroid and am my old self again.

Fibrojay

[Guest guest]

Hi

- this is one of the worries with NHS doctors treating hypothyroidism.

They feel obligated to give you levothyroxine ONLY as the gold standard

treatment of choice as directed by the Royal College of Physicians, the British

Thyroid Association and now, all the other endocrine/thyroid associations in

the UK. They dare not go outside the RCP, BTA guidelines (guidance) for fear of

being reported to the ~GMC where they could risk losing their livelihood and

career. Their autonomy has been taken away from them because of this, and so

they blindly do what they are told and the patient's health becomes secondary.

This is why we try to encourage members to read everything they can to

understand how the metabolic system works and learn about the properties of the

different thyroid hormones. No matter how much levothyroxine they give - it

will make little difference to you if you are unable to convert it to the

active T3, then T2 and T1. The average dose appears to be around 125-150mcgs

levothyroxine, but there are many who need much higher doses such as 300mcgs. Some

researchers believe the heavier you are, the more levothyroxine your body

needs.

I

personally never encourage people to look for the equivalence between the T4

found in natural thyroid extract and the synthetic T4 because with the natural,

you are also getting the magic T3, plus T2 and T1 which are all active

hormones.

Let

us know how you go on with 200mcgs and if you decide to go up to 250mcgs, but

remember, it takes up to 6 weeks for the thyroxine to be utilised. I hope you

do well, but do remember that if the thyroxine is not converting, after a

while, you might find your symptoms returning again. It is always a good idea

at this stage to get thyroid function tests done to see whether the thyroxine

is actually converting to the active T3 - because if you are still not 'getting

there' it could be that you need to add in some Liothyronine (T3) with your

levothyroxine.

Luv

- Sheila

For some reason i feel more frighten using this tablet than armour and i think

it is to do with the doctors reluctance to give you too much. With armour you

would simply keep going up until you hit your sweet spot. Should the same

happen with levoT?

What is a normal dose on T4 only. the NHS seems to think 150 is a high dose and

would prefer most people stay around 100. i have seen some stats from the nhs

(on here i think) and it seems most people are on around 100-150.

The thing is when you use natural hormones everyone seems to say 3 grains is

about the optimum (give and take a bit) and so this would equate to 300mgs on

T4 only treatment. When i was on 2 grains i was doing very well and i have recently

increased T4 from 150 to 200mgs and i feel a lot better. i actually think my

correct dose could well be around 225, but i am waiting to see how i do on 200

for 3 weeks first.

it would be good to get confirmation of my thoughts from some more experienced

users.

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21:05:00

[Guest guest]

Thanks Sheila

When you say it takes 6 weeks to use the thyroxine does this mean i will not

notice any change until later on. You see i think i notice a change very

quickley when i have been increasing. Everyone knows how the natural hormones

seem to affect everyone, but i would really like to hear from people using

synthetic.

My problems are not a conversion one however because i do have my first bloods

from when i started thyroxine (or 5 weeks afterwards). it shows tsh totally

suppressed and

t4 = 24

t3 = 7.4

The endo said the problem was one of the t3 not being absorbed. And so after

this i started on hc. at the same time i tried to reduce down the T4 in order

to fit in with the TSH.

So 2 things were happening here. i) i was reducing and 2) i was absorbing and

clearing through the T4 a lot quicker due to more cortisol in the system.

on my last blood test in oct my T4 was down to 18 and i was taking about 135 of

levoT. they didnt test T3 this time and TSH was still suppressed.

4 days later i just became so tired and i felt terrible so i increased to 150

straight away. a week later i became tired again and this is where i wasnt sure

what was happening. only last week have i decided to increase to 200 and notice

i am getting better. i did try one night going down to 175 and the next day

felt more tired again. So you can see i am quite sensitive to levoT (similar to

taking natural products).

i am still trying to work out what it is that is the problem. i am taking

plenty of hc so i think that area is covered. i really hope it is the problem

of being optimised.

Can you confirm that i need to dose T4 the same as you do natural. ie, you keep

going higher until you hit a sweet spot. this must surley be the way to do it

and if so i think i will need much more. i wil stay on 200mg now for the next 4

weeks and then try increasing.

[Guest guest]

Hi , You will notice a change in NDT dosage very quickly because in contains rapidly metabolised hormones such as T3 and very small quantities of T2 T1 etc- the full effects won't be seen for at least 25 days as it takes that long for the T4 component to level out- T4 has a half life on 5 days ( though I have see 9 quoted) You may feel the effects sooner, but T4 does take that long to settle. > thyroid treatment > From: jphenderson@...> Date: Wed, 2 Dec 2009 09:38:04 +0000> Subject: Re: Experiences with LevoT> > Thanks Sheila> > When you say it takes 6 weeks to use the thyroxine does this mean i will not notice any change until later on. You see i think i notice a change very quickley when i have been increasing. Everyone knows how the natural hormones seem to affect everyone, but i would really like to hear from people using synthetic. > > My problems are not a conversion one however because i do have my first bloods from when i started thyroxine (or 5 weeks afterwards). it shows tsh totally suppressed and> > t4 = 24> t3 = 7.4> > The endo said the problem was one of the t3 not being absorbed. And so after this i started on hc. at the same time i tried to reduce down the T4 in order to fit in with the TSH.> > So 2 things were happening here. i) i was reducing and 2) i was absorbing and clearing through the T4 a lot quicker due to more cortisol in the system.> > on my last blood test in oct my T4 was down to 18 and i was taking about 135 of levoT. they didnt test T3 this time and TSH was still suppressed. > > 4 days later i just became so tired and i felt terrible so i increased to 150 straight away. a week later i became tired again and this is where i wasnt sure what was happening. only last week have i decided to increase to 200 and notice i am getting better. i did try one night going down to 175 and the next day felt more tired again. So you can see i am quite sensitive to levoT (similar to taking natural products).> > i am still trying to work out what it is that is the problem. i am taking plenty of hc so i think that area is covered. i really hope it is the problem of being optimised. > > Can you confirm that i need to dose T4 the same as you do natural. ie, you keep going higher until you hit a sweet spot. this must surley be the way to do it and if so i think i will need much more. i wil stay on 200mg now for the next 4 weeks and then try increasing.> > > > > > > > ------------------------------------> > TPA is not medically qualified. Consult with a qualified medical practitioner before changing medication.> >

[Guest guest]

> I went up to 250 generic T4 (levothyroxine) and still had lots of

> symptoms.

>

> I then went on a combo of generic levothyroxine and Cytomel/Cynomel, and

> went down to 137.5 of T4 and worked my way up to 37.5 of T3. Some of my

> symptoms resolved themselves, but I never felt 100 percent.

>

> I now am optimized on five grains of old Armour/Naturethroid and am my old

> self again.

>

> Fibrojay

Thanks for info Fibro

I am going to stick it out to see if i can get optimised on T4 only because i

have a long time to live and so it is going to cost a lot to buy the natural

stuff over that time.

i have a feeling the endo will not be happy with me on such a high dose and so i

will have to move over to natural any way.

[Guest guest]

,

why not ask for a trial combination of synthetic T4 and T3 - or even T3 alone.

They are both available on the NHS, unless, that is, your endocrinologist

happens to be one of the British Thyroid Association's endoprats who can't

think for themselves and do the bidding of their masters.

Luv

- Sheila

> I now am optimized on five grains of old Armour/Naturethroid and am my old

> self again.

>

> Fibrojay

Thanks for info Fibro

I am going to stick it out to see if i can get optimised on T4 only because i

have a long time to live and so it is going to cost a lot to buy the natural

stuff over that time.

i have a feeling the endo will not be happy with me on such a high dose and so

i will have to move over to natural any way.

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07:33:00

[Guest guest]

i will see how i get on. the endo has said i must not be given any t3 meds as i

have a high reading, when he wrote to the GP. i am in the care of the GP now

and they are just useless because they are not used to this sort of thing.

it seems i am on my own and so will just see how i go as i increase. when it

comes to getting more for my prescription i am sure they will say no. that is

when i will be in a sticky situation and may need to buy more myself.

> , why not ask for a trial combination of synthetic T4 and T3 - or even

> T3 alone. They are both available on the NHS, unless, that is, your

> endocrinologist happens to be one of the British Thyroid Association's

> endoprats who can't think for themselves and do the bidding of their

> masters.

>

>

[Guest guest]

Hi

I'm not very experienced but thought i'd share my experiences, which seem

unusual. It seems I cannot tolerate T3 only, nor NDT - it gives me worse

thoughts basically (depression, anxiety, flashbacks).

Yet, T4 calms all these things down very quickly (hour or two) - i have read

conflicting things, some say that the T3 cannot cross the blood brain barrier as

easily as T4 can (where it's converted to t3 i believe), others say it can with

no problem. I have read that the amygdala and hippocampus have t3 receptors, -

this perhaps explains why t4 - if it's crossing the blood brain barrier and

converting- can calm all this down very quickly in me and i feel the difference

quickly.

I just wanted to say i'm like you in a way, trying to find my ideal dose of t4.

but i notice that i can take 100mcg t4 and feel somewhat better, then 24 hours

get bad thoughts etc again and this i feel signifies a) that i need my next

dose, and that i perhaps need a little more. it's complicated by timing and

how long after i've eaten that i take the t4.

pretty much every winter for the last 6 years, around this time i have had some

kind of mental breakdown - i have so far staved this off (even managing to work

at the meoment-this time last year i was on the verge of problems, with legs

giving out and stress/depression etc): whether that's becuase of HC and or T4, i

don't know but i think it probably is.

i read on the site below that a full replacment dose is 1.7 mcg/kg per day. but

then i don't know how that ties in if someone is also producing some of their

own thyroid hormone, perhaps they need less. i am about 114kg, so need

according to this 195mcg. of course, i realiase this is a guide only - i am not

starting on 195, but like you by the sound of it, i'm working up. interestingly

though, it says you can start on full replacement dose below if you're healthy

(i guess if you're on HC, you may not be). perhaps if you calculate your

weight/dose according to this site, it will give you some *idea*. you can also

get T4 quite cheaply off various websites, as i'm sure you know about. mind you

it all adds up doesn't it when you're paying for it yourself, especially if

you're on a fairly hefty dose.

i hope the info below helps

chris

http://www.rxlist.com/synthroid-drug.htm

" Therapy may begin at full replacement doses in otherwise healthy individuals

less than 50 years old and in those older than 50 years who have been recently

treated for hyperthyroidism or who have been hypothyroid for only a short time

(such as a few months). The average full replacement dose of levothyroxine

sodium is approximately 1.7 mcg/kg/day (e.g., 100-125 mcg/dayfor a 70 kg adult).

Older patients may require less than 1 mcg/kg/day. Levothyroxine sodium doses

greater than 200 mcg/day are seldom required. An inadequate response to daily

doses ¡Ý 300 mcg/day is rare and may indicate poor compliance, malabsorption,

and/or drug interactions. "

[Guest guest]

hi Chris

that info is very useful. so i need 1.7 x 80kg = 136mg.

Well i was on 2 grains before i started on the t4 and so i jumped in straight at

100. then raised to 150 within 10 days. 2 grains = 200mg you see. So now i am

on the same as before and i wasnt fully optimised then either.

if i take 175 mgs tonight i am sure i will become much more tired tomorrow. in

the past few weeks i have been experimenting and i added in an extra 25mg in the

day one time as i felt so awful. So when i came to dose my normal amount at

bedtime i felt loads better that day. Probably because i had a higher t4 amount

in the system. so it seems i am very sensitive to the t4. i was thinking my

body takes increases well and then produces more RT3 over the next day or two to

compensate for the boost you have on increase. this is a guess and i have no

idea if it is what is actually happening.

it good to talk to another person trying to win through with the synthetic

stuff.

[Guest guest]

Another thing as you mentioned timing of taking the T4.

The book " understanding thyroid disorders " by dr toft (in assoc. with the BMI)

states the best time to take thyroid meds is at night before bed. i have tried

this and have not experienced any negative effects at all. i also havent

noticed any positive ones as well, but i prefer to take it at this time as you

dont have to remember to have an emptyish stomach.

[Guest guest]

What

medication were you taking when you had the Free T3 tested - was this before

you started taking levothyroxine alone? Let us know what the FT3 reading

was and the reference range too.

Luv

- Sheila

i will see how i get on. the endo has said i

must not be given any t3 meds as i have a high reading, when he wrote to the

GP. i am in the care of the GP now and they are just useless because they are

not used to this sort of thing.

it seems i am on my own and so will just see how i go as i increase. when it

comes to getting more for my prescription i am sure they will say no. that is

when i will be in a sticky situation and may need to buy more myself.

> , why not ask for a trial combination of synthetic T4 and T3 - or even

> T3 alone. They are both available on the NHS, unless, that is, your

> endocrinologist happens to be one of the British Thyroid Association's

> endoprats who can't think for themselves and do the bidding of their

> masters.

>

>

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07:33:00

[Guest guest]

A

small study has been done on only 12 people taking levothyroxine, but it showed

that taking levothyroxine when you go to bed gives a better nights sleep and

helps you feel better during the day. This is to do with the absorption by the

intestines. Make sure you have nothing to eat before going to bed for at least

an hour.

Luv

- Sheila

The book " understanding thyroid disorders " by dr toft (in assoc. with

the BMI) states the best time to take thyroid meds is at night before bed. i

have tried this and have not experienced any negative effects at all. i also

havent noticed any positive ones as well, but i prefer to take it at this time

as you dont have to remember to have an emptyish stomach.

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07:33:00

[Guest guest]

The level was after i had started on levoT at 150mgs for 6 weeks.

t3 = 7.4 (3.5-6.5) however the reference range should really go up to 8

according to Toft.

>

> What medication were you taking when you had the Free T3 tested - was

> this before you started taking levothyroxine alone? Let us know what the

> FT3 reading was and the reference range too.

>

> Luv - Sheila

>

>

[Guest guest]

Might

sound a daft question , but are you 100% certain that you are hypothyroid.

Could your symptoms and problems be down to other hormone deficiencies?

Luv

- Sheila

The level was after i had started on levoT at 150mgs for 6

weeks.

t3 = 7.4 (3.5-6.5) however the reference range should really go up to 8

according to Toft.

>

> What medication were you taking when you had the Free T3 tested - was

> this before you started taking levothyroxine alone? Let us know what the

> FT3 reading was and the reference range too.

>

> Luv - Sheila

>

>

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07:32:00

[Guest guest]

I have no idea really. i just do not know what is going wrong with me. and i

doubt anyone else would as well.

i do know if i stop thyroid meds i will become very ill and so i think i

definitley have a thyroid problem. i did this last september thinking i was

better on natural thyroid meds. i became so ill in december and so i started on

armour again in feb. i recovered, but i am never get fully well. i have had

many days this yr of being fully well and it is fantastic, but it doesnt last.

i am supporting the adrenals with 20mg of cortef and if i go higher i dont

notice any difference. iron is fine and b12 is low (300), but i take a

supplement for that so it should be ok. i have not tested candidia though.

the endo said the high T3 reading was good because i comvert well, but it wasnt

being absorbed by the cells properly. i thought this was because of lowish

cortisol and so started the hc. i suppose i could reduce the hc to see if it is

now working.

the final thing to consider is testosterone and this is fine.

> >

> > What medication were you taking when you had the Free T3 tested - was

> > this before you started taking levothyroxine alone? Let us know what the

> > FT3 reading was and the reference range too.

> >

> > Luv - Sheila

> >

> >

>

>

>

> No virus found in this incoming message.

> Checked by AVG - www.avg.com

> Version: 8.5.426 / Virus Database: 270.14.91/2542 - Release Date: 12/03/09

> 07:32:00

>

[Guest guest]

Hi T4 does not convert to T3 in the brain, it relies on conversion elsewhere- mostly in the liver- this is why those of us who can't convert suffer so badly form brain fog. Can you post links to where it says T4 is converted in the brain? I really hate it when it says that no response to 300 mcg T4 is due to patients not taking the pills! Blame the poor patient for inadequate treatment!! If you can't convert T4 to T3 then of course it won't work! Also unconverted T4 gets stuck in the joints causing stiffness- http://www.drlowe.com. If you can't tolerate any T3 containing med it is usually due to poor adrenal function or allergy to fillers in the pills. > thyroid treatment > From: chrisjtaylor46@...> Date: Wed, 2 Dec 2009 22:01:01 +0000> Subject: Re: Experiences with LevoT> > Hi > > I'm not very experienced but thought i'd share my experiences, which seem unusual. It seems I cannot tolerate T3 only, nor NDT - it gives me worse thoughts basically (depression, anxiety, flashbacks).> > Yet, T4 calms all these things down very quickly (hour or two) - i have read conflicting things, some say that the T3 cannot cross the blood brain barrier as easily as T4 can (where it's converted to t3 i believe), others say it can with no problem. I have read that the amygdala and hippocampus have t3 receptors, - this perhaps explains why t4 - if it's crossing the blood brain barrier and converting- can calm all this down very quickly in me and i feel the difference quickly.> > I just wanted to say i'm like you in a way, trying to find my ideal dose of t4. but i notice that i can take 100mcg t4 and feel somewhat better, then 24 hours get bad thoughts etc again and this i feel signifies a) that i need my next dose, and that i perhaps need a little more. it's complicated by timing and how long after i've eaten that i take the t4.> > pretty much every winter for the last 6 years, around this time i have had some kind of mental breakdown - i have so far staved this off (even managing to work at the meoment-this time last year i was on the verge of problems, with legs giving out and stress/depression etc): whether that's becuase of HC and or T4, i don't know but i think it probably is.> > i read on the site below that a full replacment dose is 1.7 mcg/kg per day. but then i don't know how that ties in if someone is also producing some of their own thyroid hormone, perhaps they need less. i am about 114kg, so need according to this 195mcg. of course, i realiase this is a guide only - i am not starting on 195, but like you by the sound of it, i'm working up. interestingly though, it says you can start on full replacement dose below if you're healthy (i guess if you're on HC, you may not be). perhaps if you calculate your weight/dose according to this site, it will give you some *idea*. you can also get T4 quite cheaply off various websites, as i'm sure you know about. mind you it all adds up doesn't it when you're paying for it yourself, especially if you're on a fairly hefty dose.> > i hope the info below helps> > chris> > http://www.rxlist.com/synthroid-drug.htm> "Therapy may begin at full replacement doses in otherwise healthy individuals less than 50 years old and in those older than 50 years who have been recently treated for hyperthyroidism or who have been hypothyroid for only a short time (such as a few months). The average full replacement dose of levothyroxine sodium is approximately 1.7 mcg/kg/day (e.g., 100-125 mcg/dayfor a 70 kg adult). Older patients may require less than 1 mcg/kg/day. Levothyroxine sodium doses greater than 200 mcg/day are seldom required. An inadequate response to daily doses ¡Ý 300 mcg/day is rare and may indicate poor compliance, malabsorption, and/or drug interactions."> > > > > ------------------------------------> > TPA is not medically qualified. Consult with a qualified medical practitioner before changing medication.> >

[Guest guest]

Hi Sheila

This morning i tried to fiddle around with my hc dose and only took 5mgs instead

of the 7.5. i have been doing 7.5 x2 and then 2.5 x2 = 20mgs.

Anyway i felt ok'ish this morning and took the 5mgs, but started to feel worse.

So at 11am i took the other 2,5mgs and at this moment i can feel my body working

properly again.

this indicates to me the problem i have is to do with my adrenals and it is

sensitive to the amounts of hc. i would probably have been fine taking the

normal 7,5mg.

It really is a pain getting balanced.

> >

> > What medication were you taking when you had the Free T3 tested - was

> > this before you started taking levothyroxine alone? Let us know what the

> > FT3 reading was and the reference range too.

> >

> > Luv - Sheila

> >

> >

>

>

>

> No virus found in this incoming message.

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> Version: 8.5.426 / Virus Database: 270.14.91/2542 - Release Date: 12/03/09

> 07:32:00

>

[Guest guest]

> Can you post links to where it says T4 is converted in the brain?

I will try to find some.

Can you post links to where it says that T3 crosses the blood brain barrier? I'm

not convinced it does, at least, not as readily as T4.

C

>

>

> Hi

> T4 does not convert to T3 in the brain, it relies on conversion

elsewhere- mostly in the liver- this is why those of us who can't convert suffer

so badly form brain fog.

> I really hate it when it says that no response to 300 mcg T4 is due to

patients not taking the pills! Blame the poor patient for inadequate treatment!!

If you can't convert T4 to T3 then of course it won't work! Also unconverted T4

gets stuck in the joints causing stiffness- http://www.drlowe.com.

> If you can't tolerate any T3 containing med it is usually due to poor adrenal

function or allergy to fillers in the pills.

[Guest guest]

http://www.thyroid-guide.org/all-about-your-thyroid/

Cells of the brain are a major target for thyroid hormone. Thyroid hormones play

a particularly crucial role in brain development during pregnancy[4]. A

transport protein (OATP1C1) has been identified that seems to be important for

T4 transport across the blood brain barrier[5]. A second transport protein

(MCT8) is important for T3 transport across brain cell membranes[5].

-

t4 has more of an effect in *me* on *my* brain. and that is not due to adrenal

issues...

chris

[Guest guest]

Hi I'll look up my files to answer your question re T3- but this may take some time as my files are very fat! All I can say is that artificial T4 keeps me alive, but that's all. T3 keeps me well. Thanks for that reference. > thyroid treatment > From: chrisjtaylor46@...> Date: Fri, 4 Dec 2009 17:26:12 +0000> Subject: Re: Experiences with LevoT> > http://www.thyroid-guide.org/all-about-your-thyroid/> > Cells of the brain are a major target for thyroid hormone. Thyroid hormones play a particularly crucial role in brain development during pregnancy[4]. A transport protein (OATP1C1) has been identified that seems to be important for T4 transport across the blood brain barrier[5]. A second transport protein (MCT8) is important for T3 transport across brain cell membranes[5].> > - > > t4 has more of an effect in *me* on *my* brain. and that is not due to adrenal issues...> > chris> > > > ------------------------------------> > TPA is not medically qualified. Consult with a qualified medical practitioner before changing medication.> >

[Guest guest]

Hi you're right. The following extract from Thyroid Manager if you want to do more reading. However this site does confirm that most T4 to T3 deiodination is done in the liver. In the following extract D1, D2 etc are deoidinase hormones NOT vit D The fact that you get an instant response to T4 is most unusual, but that just goes to show how different we all are- the response I get to T4 is to feel ill!

Since most actions of thyroid hormone are initiated by binding of T3 to its

nuclear receptors, it is important to consider the role of the processes

discussed above in the regulation of nuclear T3. There are two sources of

intracellular T3, i.e. T3 derived from plasma T3, and T3

produced locally from T4, and the degree to which they contribute to the

occupied receptors varies among the different tissues (4,108, 109). The liver

and kidneys are typical of most tissues in the body in which most of the T3 specifically

bound to the T3 receptor is derived directly from plasma. In the cerebral

cortex, BAT, and anterior pituitary there is a substantial contribution to

nuclear T3 from locally produced T3.

Under normal conditions, plasma T3 is largely derived from deiodination of

T4 by D1 in liver and kidneys (1-4). Most tissues depend on plasma T3, but some

critical tissues, such as the brain, use D2 for local T4 to T3 conversion,

which allows them to regulate intracellular T3 levels independent of variations

in plasma T3 (1-4). Local T3 production may be an autocrine process, where T3

is produced in the same cells where it acts, or a paracrine mechanism, where T3

production and action take place in neighboring cells. The latter appears very

important for T3 action in the brain, where neurons are the primary target

cells for T3 produced by D2 expressed in nearby astrocytes (138, 139). Another

example is the action of locally produced T3 in the developing cochlea (76).

D3 plays an additional important role in maintaining intracellular T3

concentrations in these tissues by catalyzing the degradation of T3 in case of

excess or by diverting the metabolism of T4 to rT3. Indeed, the adaptations of

deiodinase activities in response to changes in thyroid state are thought to serve

the purpose of keeping intracellular T3 in the brain constant. Thus, when T4

supply is decreased in hypothyroidism, both D1 and D3 activities are

down-regulated, so that relatively more T4 is available for conversion to T3 by

D2 in the brain, the activity of which is up-regulated. Opposite changes occur

in hyperthyroidism. These adaptations are not only important for the optimal

function of the brain in adult life, they are also essential for the

development of the brain which is critically dependent on thyroid hormone

(110). Although the adaptations in deiodinase activities during hypo- or hyper­thyroidism

go a long way in securing T3 availability in the brain, in severe iodine

deficiency they may not fully compensate for the extreme decrease in T4 supply

(110). This may result in severe impairment of neurological development in the

child even when plasma T3 levels in the mother are sufficient to maintain a

euthyroid state (110).

> thyroid treatment > From: chrisjtaylor46@...> Date: Fri, 4 Dec 2009 17:26:12 +0000> Subject: Re: Experiences with LevoT> > http://www.thyroid-guide.org/all-about-your-thyroid/> > Cells of the brain are a major target for thyroid hormone. Thyroid hormones play a particularly crucial role in brain development during pregnancy[4]. A transport protein (OATP1C1) has been identified that seems to be important for T4 transport across the blood brain barrier[5]. A second transport protein (MCT8) is important for T3 transport across brain cell membranes[5].> > - > > t4 has more of an effect in *me* on *my* brain. and that is not due to adrenal issues...> > chris> > > > ------------------------------------> > TPA is not medically qualified. Consult with a qualified medical practitioner before changing medication.> >

[Guest guest]

thanks

i think then that could explain why i am so responsive to t4, do you agree?

> D3 plays an additional important role in maintaining intracellular T3

> concentrations in these tissues by catalyzing the degradation of T3 in case of

> excess or by diverting the metabolism of T4 to rT3. Indeed, the adaptations of

> deiodinase activities in response to changes in thyroid state are thought to

serve

> the purpose of keeping intracellular T3 in the brain constant. Thus, when T4

> supply is decreased in hypothyroidism, both D1 and D3 activities are

> down-regulated, so that relatively more T4 is available for conversion to T3

by

> D2 in the brain, the activity of which is up-regulated. Opposite changes occur

> in hyperthyroidism.

[Guest guest]

Hi Possibly, but there could be other causes- if you suffer from adrenal insufficiency for instance it can make you hypersensitive to thyroid meds too - see Dr. Peatfields book-Your Thyroid and how to keep it Healthy. The fact still remains that regular dosing with T4 won't stabilise until you have been taking the same dose daily for 6 weeks due to the long half life. Taking a few pills here and there doesn't help you get to the bottom of your problems. > thyroid treatment > From: chrisjtaylor46@...> Date: Sat, 5 Dec 2009 17:34:35 +0000> Subject: Re: Experiences with LevoT> > thanks > > i think then that could explain why i am so responsive to t4, do you agree?> > > > D3 plays an additional important role in maintaining intracellular T3> > concentrations in these tissues by catalyzing the degradation of T3 in case of> > excess or by diverting the metabolism of T4 to rT3. Indeed, the adaptations of> > deiodinase activities in response to changes in thyroid state are thought to serve> > the purpose of keeping intracellular T3 in the brain constant. Thus, when T4> > supply is decreased in hypothyroidism, both D1 and D3 activities are> > down-regulated, so that relatively more T4 is available for conversion to T3 by> > D2 in the brain, the activity of which is up-regulated. Opposite changes occur> > in hyperthyroidism. > > > > ------------------------------------> > TPA is not medically qualified. Consult with a qualified medical practitioner before changing medication.> >

[Guest guest]

Thanks, I've read that book several times trying to work out what's wrong. Dr P

does not know why i cannot tolerate T3, either.

> The fact still remains that regular dosing with T4 won't stabilise until you

have been taking the same dose daily for 6 weeks due to the long half life.

Taking a few pills here and there doesn't help you get to the bottom of your

problems.

i realise this!! :-)

thanks

Chris