And the verdict is...

Just a follow up from my last post:
Praise God, it was thyroid rather then kidneys. However, I'm type-3 thyrotoxic (sp?) and will need treatment. Still, overactive thyroid is pretty straight forward to treat apparently...

My T3 reading was 8.22, which is outside normal (which was around 6). My T4 was reasonably high as well at 22, but that's the very top end of normal.

So what does this all mean? Well, apparently overactive thyroid is caused by something, and it's either going to be a virus or an auto-immune disease, and at the moment it looks more like the latter then the former. My doctor tells me that viral thyroiditis is fairly short-lived, and the symptoms seem to go back further then it's normal length. However, this could be coincidental. I am really quite fat and out of shape, so some of the symptoms we're seeing (like high blood presure) could be caused by that.
If it's auto-immune, it'll probably be something like Grave's disease(here's a PDF). This is still manageable, but would require probably a lifetime of tablet-taking. Not fun, but also not the end of the world. There are far worse things that can happen.

So yeah - anxiety crisis over. Yes, I have a health condition, but it's something relativley minor, and easily treated. Even in the (increadibly unlikely) absolute worst case if it was thyroid cancer, apparently treatment is pretty much always successful - even if there are secondary cancers. If I had to have cancer, that's the type I'd want. So yeah, all possible outcomes explored, and all seem to be manageable at an acceptable non-lifechanging level.

On with the tests... :(