What causes facial hair on women?

Lower estrogen level: There can be several things but the most common in a 40 yo is lower estrogen as one approaches menopause, or the mildly elevated androgen production that one sees around menopause. However one must consider an endocrine tumor. The physician should ask other questions such as change in voice, change in periods, hair growth in other areas, medications, muscle hypertrophy, etc. ? Endocrine w/u.