Yes it is complicated. If you read Andy Cutler's book, he has a section where he gives indications for many signs and symptoms of mercury toxicity. It includes various blood tests and urine tests. He does not recommend challenge tests as they can cause redistribution and sometimes very bad side effects (as happened to me with a DMPS challenge) He does however recommend the urine porphyrins test. You can read more about it in his book. Mercury will not show up in hair usually, but there would be abnormal mineral transport on a hair analysis in most cases.

Sandra