My 18 year old DD's hair has been getting thinnner and thinner. No bald patches , but noticeably thinner than a couple of years ago. Her skin is also much spottier thannit ever was. About a year ago she had some blood tests done and was told she had low iron levels. Checked again a few months ago and levels fine. At our surgery you ring up, Dr calls you back with telephone consultation . If necessary arranges blood tests, appointment for you to go in. MyDD is in 6th form . She is happy to speak to Dr but she tends to not actually say what is worrying her etc. So GP may not even get to see the thinning hair! She was robbed off before with a comment about eating more spinach.
You could ask to get her thyroid levels and B12 checked. You should also get a print of the results to check where she is in range. She might be at the bottom rather than optimum! It can make a big difference. Ferritin should be half way in range to feel well.