My 15 year old is loosing hair and has less htn half hair left, she has iron 24 does she need iron suppliments?

Needs MD exam: Your daughter needs to be seen by a physician to sort out the alopecia and hypertension. Ask your MD about having her thyroid function checked out.

What iron test?: There are different ways of testing iron, and I am assuming you are referring to ferritin, or storage iron. Normal range is 18-160, so supplemental iron is healthy, but unlikely to be the cause of hair loss. If testing Hct, then 36-42 is normal range. Hair loss can be related to severe illness in the recent past, hormone imbalance, immune process, or trichotillomania. Please get checked.