why dextro thyroxine not using?: - Thyroid UK
why dextro thyroxine not using?
what is the benefit of levo thyroxine over dextro?
Dextrothyroxine has been tried in the past. It had undesirable effects in at least some subjects. Further, there are questions over whether it was the D-thryoxine that had the effect, or contamination by L-thyroxine. It requires a very much larger dose.
ncbi.nlm.nih.gov/pubmed/649...
It was only a few years ago that the name levothyroxine was made standard (rather than thyroxine) for the medicine to remove any possible ambiguity.
And it is levothyroxine that we ourselves produce.
Rod
Yes, the body tends to prefer one stereoisomer over the other for various things such as amino acids (L) and sugars (D). I find it all very fascinating. It's interesting that two substances that are chemically identical but whose molecules are mirror images of each other can have such different effects on the body. I believe reverse T3 is a stereoisomer (mirror image) of T3.
My favourite is a cough mixture ingredient DXM (dextromethorphan) who's stereoisomer is an opiate many, many times stronger. Chemically identical but a mirror image having a very different effect on the human body. DXM in normal doses is a cough suppressant (in larger doses is rather nasty to the brain although some people use it as a recreational drug). It's stereoisomer is an opiate analgesic and very much stronger. The reason it is one of my favourites is that it has been used in murder mysteries. The murderer leaves a bottle of cough mixture containing DXM at the scene but actually administers the opiate levomethorphan to kill the victim. When a tox screen is carried out, it can't distinguish between the isomers (as they are chemically identical, the molecules are just mirror images of each other) and, as the cough mixture was at the scene, it is assumed that it was just from that. The victim is then labelled as dying from natural causes. Of course the murderer always gets caught eventually 
Sorry if that was rather off-topic. I enjoy things like this 
Think you might have made a jump too far, Carolyn. 
T3 is T4 with one particular iodine atom removed (from the outer carbon ring). rT3 is when it is a different iodine atom that has been removed (from the inner carbon ring).
But D-thyroxine can be converted into D-T3 and its partner rDT3.
en.wikipedia.org/wiki/Thyro...
Rod
Anxiety on thyroxine 
Thyroxine and osteoporosis
Thyroxine and prednisalone.
