Hair sample analysis
From samples of human hair it is possible to determine if the donor has used some drugs or pharmaceuticals in the past few weeks, it is also possible to trace heavy metal poisoning (basically it can test for something that shouldn't be or have been in the body) and it is possible to look for genetic disorders. But what it cannot do is be used as a diagnostic tool to determine someone's state of wellness or look for mineral and elemental imbalances. Services are offered by some 'labs' (a google search showed this link: https://bit.ly/2TnlGaG) to test for "The body's mineral deficiencies and toxin levels" and then once you spend £70 or so on a test kit and send back your sample, the 'lab' will send you a report showing you the "nutritional and therapeutic measures recommended to correct the imbalances and aid the removal of toxins from the body after testing." Of course they recommend you "Use our range of supporting nutrients and mineral supplements to re-balance and redress any mineral deficiencies or excesses in your body."
This alt-med practice has been going on for years. In 1983, the New York Times criticized the industry for inconsistent results, fraudulent practices, unscientific aspects, and being "a consumer rip off that in some cases is dangerous". Often the test is offered by Chelation Therapists. They offer treatments for heavy metal poisoning and use the test to claim the patient has high levels of lead or antimony and then offering the chelation treatment. Chelation is a legitimate medical procedure for genuine ailments such as severe lead poisoning and used as an immediate treatment to remove dangerously high levels of these substances. It should not be used for 'mineral deficiencies'. Our mineral levels can fluctuate for many legitimate reasons and chelation itself can be dangerous or even lethal, especially if not done properly.
Many studies have been done on the claims made by these quack-doctors. The FDA opposes its use in testing for medical therapies and a 2001 Investigation found "Hair mineral analysis from these laboratories was unreliable, and we recommend that health care practitioners refrain from using such analyses to assess individual nutritional status or suspected environmental exposures. As Dr Stephen Barrett wrote on the Quackwatch website: "Should you encounter a practitioner who uses hair analysis for any of these purposes, run for the nearest exit!".