Testing for heavy metals stinks. You'll be looking for clues.
Some people such as me can look back and remember significant exposures. Others have no idea and will never know. What if someone broke a Hg thermometer in your bedroom carpet days before you moved in.
Remember most heavy metal test are best for recent exposure, especially blood tests. Old exposures of HMs get stuck in bone, brain and other sensitive organs. Not much is floating around where it can be easily tested.
At least hair gives us a 3 or so month window. There is also the theory by A, Cutler about how Hg affects movement--transport--of minerals in the body.
It is easy to understand why so many doctors don't want to mess with heavy metal detox. Testing stinks, there are too many options for treatment and too many people report adverse reactions to treatment. Furthermore people who have an HM problem virtually always have some problems with mood and clear thinking. It is too easy for the doctor to think the person is "nuts." When HM detox works well the person's health improves such that they no longer need to visit the doctor so often! It understandably feels risky for the doctor to get involved.