My daughter had some tests carried out 2 years ago which showed she had a very high prolactin level - after having a normal MRI scan it was decided there was no sign of anything wrong with her pituitary gland, she was also told she had a borderline under active thyroid function which we have had checked every 4 months since. Two months ago her levels became low enough to start treatment. My concern is that there is something a Miss with her pituitary gland which is causing this but our GP says not. What causes a 17 year old to have this thyroid problem? And should it not be investigated as to why she has this? Does anyone have any advice for me?