I wrote this for out thyroid discussion....
We are a society that wants everything at warp speed...thyroid is ploddingly slow.
If I make a change in thyroid medication today, my blood will not show the full results of that change for 6 weeks. It is preferred to gradually increase every 6 weeks because if you overshoot optimum, the symptoms of hyper are going to be just as troubling as those of hypo are. So once T4 and TSH were where my endocrinologist wanted them, she increased T3 only. Think radio station, you have reception... and static. So you fine tune the reception with T3 and lose the static.
Only considering patients on Levothyroxine-Synthroid, about half will feel great improvement if their T3 is about 75% of normal range, for me that level is about 3.7.
Remember, my endocrinologist exclusively prescribes Synthroid not Levothyroxine. Her prescriptions specifically prohibit substitution.
T4 (Thyroxine), named for it's 4 iodine atoms, maintains a relatively stable blood level and is therefore termed long acting.
T3 (Triiodothyronine), named for it's 3 iodine atoms, fluctuates and is therefore termed short acting.
Let us ingest T4 (Thyroxine) Through chemical reaction, our body takes in T4 and converts the T4 into T3 (Triiodothyronine) through chemical reaction, our body takes 4 iodine atoms and converts it into a new compound with only 3 iodine atoms.
So from a strick biological & chemical viewpoint, many say if I can use one chemical compound to make the other chemical compound, I only need T4.
But, many studies have shown that about half of the patients on T4 feel better on both T4 and T3.
NEWS FLASH
Armour's Thyroid versus Synthroid...the mystery revealed.
One grain of ARMOUR'S THYROID is 60 mg.
Each 60 mg of ARMOUR'S THYROID contains .038 mg (or 38 mcg) of T4
AND each 60 mg of ARMOUR'S THYROID contains 9 mcg of T3 , plus unmeasured amounts of T2, T1 and calcitonin.
SYNTHROID is all T4
which explains why the addition of CYTOMEL (which is all T3) makes fifty percent or so of SYNTHROID users feel so much better.
Remember T3 is a short half life which is why T4 is prescribed as the backbone of treatment...some of us do not effectively metabolize T4 into T3. For these individuals, supplemental T3 should be considered.