Dear Tex I did one of these last year, it tests you for about 10 different metals, mine showed up very positive, but you still cant be sure which metal it is. I would say the Melissa blood test is far more accurate because this actully test you which metals your body is sensitive too. I aso had an EDTA challenge test and my Mercury came out very low, but other metals like Nickel came out high. Personally I think those home tests do definately work but it wont tell you what metal you dealing with. Melissa is much more accurate Love and best wishes Tracy xxxxxx