I have had thin, fine hair all my life. Everyone else in my family has a thick head of hair. Mine started coming out in 1994 when my Father was very ill and I was flying (I hate to fly) East to West, back & forth for 6 wks before he passed and my Mother had passed away in '93. My thyroid is checked every year and is fine. Thyroid controls your hormones...I went thru Menopause long before my parents passing. It is still continuing to thin....I just try to fix it so it doesn't show. I do have a lot of stress in my life and that is probably the cause at the present.