Mine was done through the ND. I'm pretty sure it was done through Metametrix, as was the Liver Detox test. The type of Liver detox test checking the Phase 1 and Phase 2 pathways, and tests like this Adrenal Saliva test, MD's would laugh you out of the office, unfortunately.
Genova (used to be Greater Smokies Lab) does the tests too, but I don't know if they have to be done through ND's. Doctor's Data is another lab that does the testing.
I found a place online where you can order the kit and not have to go through an ND. They will then do a 30 minute consultation to go over the results with you. They also have hair analysis tests for heavy metals and minerals.