From my experience with doctors and from what I've read, you are right. They aren't looking for toxins so of course they don't find them. I was urinating very frequently, every 20 to 30 minutes and would get ill feeling and have a headache if I had to wait too long to go and I was sent to a kidney dr. who ran all the "standard test" and told me my kidneys were good.

I've also heard that liver function test don't actually show how the liver is functioning.