Hair analysis, basically, is the scientific examination of a hair sample. In this test, a sample of your hair is taken from the back of your head and sent to a laboratory where it is checked for signs of health problems.
Hair follicle test analysis is still an evolving science, and while it has a lot of potential, we need to be careful about what we expect hair analysis to tell us about the health of the person.
The scientific basis of hair follicle test analysis is simple, when new hair cells are forming in the hair follicle, they take in traces of substances going through the blood stream of the individual. As hair grows, the new cells push out the older ones, and as cells come out of the bulb, they die and harden. And thus they create a long lasting record of whatever was in the blood of the person when they were forming.
Besides the hair stand itself, the sebum that coats the hair (from the sebaceous gland connects to the hair follicle) also contains traces of the drugs and minerals flowing through your body.