T3 is the normal lab stuff you get for hypothyroid. They give you T4 and measure T3. T4 is basically never measured.

Nature works like this; thyroid produces T4 and T3. Then some of the T4 is also converted to T3. When you get T4 as a treatment, you rely on your body to readily convert it to T3 without problems.

In the past, people were treated with natural thyroid that had T3, T4 and even more stuff. Now they are given pure T4 and MANY don't do well with this. Some need a tad of cytomel (T3) but it is basically almost never given. Why? I guess it's too much of a hassle to figure out the proportions needed, better let the patient suffer.

Usually with T4, you only get partial remission from hypothyroid. Some do well on it, but actually most don't get the full health back. The absolute most common is that people on T4 only cannot lose extra weight. But also, those who suffer more, can have an even more incomplete remission with loss of energy and yea, depression.

When I started on T4 my life turned around. I got much less depressed and I got energy back! But as time passed, I'm losing that and getting back to the old stuff. But I can't complain about it because these days my labs are fine. Before, when I started feeling crappy, I had high TSH and they added more meds and I got better. Now my T3 and TSH are perfect and I still feel hypothyroid. My skin and hair is crap too.

In the past before fancy tests, people were tested in two ways if they had enough supplementation. They needed a normal body temp and a normal pulse rate. A too low pulse rate and low BP and they got more meds. These days, when they do blood work, they treat your numbers. Which means you can be undertreated and they still won't give you more meds. You know you are undertread if you have a very low core temp and very slow pulse rate (resting). But they won't know it because they only believe in their numbers.

It helps some people a lot to get T3. Some of course it doesn't help, it depends on the type of problem they have. But if you fail to go into remission I think T3 should always be offered, and it's NOT.

These days, treating thyroid illness might be more exact, but the patients FEEL worse compared to in the past. So it's sad that we took a step backwards and no one dares fixing what is wrong with the current view.

Also there are a lot of things they don't tell you, like rationing your iodine if your hypo is autoimmune, or that supplementing with selenium is a good thing. Also old knowledge lost to the brave new world.