More info on conversion of T4 to T3

[Guest guest]

" About 20 percent of the body's T3 comes from the synthesis of T3

within the thyroid. The rest of the T3 is derived when an enzyme

(called a deiodinase) removes one iodine molecule from T4. While T4

is converted to T3 in a number of locations in the body, the main

place that this occurs is in the liver.

All the thyroid hormone metabolic activity comes from T3. Except

during pregnancy, when T4 is needed for the fetus to develop

properly, T4 is in the body just to be converted to T3. In a normally-

functioning thyroid, enough of this conversion process takes place.

Most people with hypothyroidism do not have normally-functioning

thyroids, however.

Imagine you go to a foreign country with a stack of money in your

country's currency to convert into the local currency when you get

there — and then, for some reason, you're unable to convert it.

You're loaded with cash, but you can't spend it. The situation is

similar for those patients on T4-only medication who may not be able

to able to convert that T4 adequately into T3.

(a comment from Janie about the last sentence above: the problem with

being on T4-only meds is not just that your body is unable " to

convert that T4 adequately into T3. " It's because you are not getting

direct T3, in addition!)

This isn't a problem for everyone with hypothyroidism, but lab test

results sometimes don't indicate a conversion problem when there is

one. The majority of those on T4 alone who still have symptoms of

hypothyroidism benefit from taking T3 in a natural or synthetic form,

usually in addition to T4. "

http://www.bites-medical.org/hypo/function.html#conv

[Guest guest]

GREAT INFO!!! Thanks for sending!!

More info on conversion of T4 to T3

" About 20 percent of the body's T3 comes from the synthesis of T3

within the thyroid. The rest of the T3 is derived when an enzyme

(called a deiodinase) removes one iodine molecule from T4. While T4

is converted to T3 in a number of locations in the body, the main

place that this occurs is in the liver.

All the thyroid hormone metabolic activity comes from T3. Except

during pregnancy, when T4 is needed for the fetus to develop

properly, T4 is in the body just to be converted to T3. In a normally-

functioning thyroid, enough of this conversion process takes place.

Most people with hypothyroidism do not have normally-functioning

thyroids, however.

Imagine you go to a foreign country with a stack of money in your

country's currency to convert into the local currency when you get

there - and then, for some reason, you're unable to convert it.

You're loaded with cash, but you can't spend it. The situation is

similar for those patients on T4-only medication who may not be able

to able to convert that T4 adequately into T3.

(a comment from Janie about the last sentence above: the problem with

being on T4-only meds is not just that your body is unable " to

convert that T4 adequately into T3. " It's because you are not getting

direct T3, in addition!)

This isn't a problem for everyone with hypothyroidism, but lab test

results sometimes don't indicate a conversion problem when there is

one. The majority of those on T4 alone who still have symptoms of

hypothyroidism benefit from taking T3 in a natural or synthetic form,

usually in addition to T4. "

http://www.bites-medical.org/hypo/function.html#conv