Re: t4 storage-buildup in the blood

[Guest guest]

>

> OK, a big gold star on your report card for finding these

> interesting research articles.

>

> As far as the statement " The in vivo T4 to T3 conversion, as a

> function of weight, accounted for 21% of cerebellum needs and 43%

of

> brain needs. The rest was provided by T3 uptake. " ---if only 21% of

> cerebellum's needs and 43% of the brain's needs come from the

> conversion, it also shows the great need for the " direct " T3.

>

> Because if I am reading it right, that would mean that 79% of the

> cerebellum's needs and 57% of the brains needs are for the direct

T3.

>

> Makes you wonder once again why any doc could defend the practice

of

> giving a patient ONLY T4-only meds........

>

> Janie

>

>

> > http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?

> cmd=Retrieve&db=PubMed&list_uids=11094382&dopt=Abstract

> >

I cring when I hear about how someone is doing 'great' on just

synthroid. I also cring when I hear how someone is doing 'great' on

cytomel alone. We need them both - otherwise our bodies wouldn't

make them.

ONTH, The problem with these studies is you can find one to back up

just about anything (I once found one that wherein athsma inhallers

were made out of chocolate to ensure they were used):

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?

cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=6470136

In hypothyroidism, the Cx is protected by an increase in the

efficiency of T4 to T3 conversion and a prolong residence time of T3

in the tissue, whereas the Cm is protected only by the latter.

Because of the large fraction of the T3 produced locally and the

active turnover rate of T3 in the brain, reductions in T3 removal

rate are of utmost importance for T3 homeostasis in these tissues.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?

cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=4017962

Although there were no regional differences between the total T3

levels in the brain, the relative contribution of locally converted

T3(T4) was 65% in the cerebral cortex and only 22% in the spinal cord

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?

cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=3766050

From these data the concentrations of T4, total T3 and T3 derived

from local T4 to T3 conversion (LcT3(T4)) in tissue could be

calculated. The relative mean contribution of LcT3(T4) to the total

T3 in Cerebral cotex (75%), thymus (31%), testis (43%) and brown

adipose tissue (65%) from hypothyroid rats was higher than that

determined for euthyroid animals (66%, 19%, 29% and 27%,

respectively). The reverse was found for the liver (15% vs 39%).