Hair Tissue Mineral Analysis comes up a lot, usually because someone online has said it will explain everything about your child. I use it. I also want to be clear about what it is and is not, because it gets oversold and that does nobody any favours.
What it is: a measurement of mineral and heavy metal levels in a hair sample, taken from a section of hair that has grown over roughly the last few months. That window is useful. It is longer than a blood test, which is a snapshot of one particular morning.
What it is not: a diagnosis. It does not tell me your child has ADHD, or autism, or anything else. It does not tell me what is wrong with them. It is one piece of information sitting alongside their history, their diet, their sleep, their digestion, and everything you tell me in the room.
I also want to be honest that testing of this kind is debated, and that laboratory methods and interpretation vary between providers.
What I can tell you is how I use it, which is cautiously, as a prompt for better questions rather than a set of answers.
When I order it, and when I do not
When I do order it, it is usually because a child's diet is very restricted, or because minerals are a reasonable thing to look at given everything else going on. When I do not order it, it is because the result would not change what I was going to suggest anyway, and I would rather you kept the money.
If a test is not going to change the plan, it is not worth doing.