The tests are of questionable reliability. That doesn't mean they are necessarily worthless, but I would be skeptical of any results.
I've heard people say that challenge tests are better. This would mean taking a chelator before giving the test. Taking a chelator is potentially dangerous if you still have silver fillings because the chelator could pull mercury out of your fillings, worsening your problem.
Silver fillings are about half mercury. The mercury leaks out of them and into your body 24/7. If you have them and heavy metal toxicity, then you can pretty much assume the fillings are a big reason for it.
I don't know much about your situation, but I highly recommend that you get the fillings out and chelate. It helped me a lot after decades of feeling "mysteriously" sick.