Hormonal changes and medical conditions. A variety of conditions can cause permanent or temporary hair loss, including hormonal changes due to pregnancy, childbirth, menopause and thyroid problems. Medical conditions include alopecia areata (al-o-PEE-she-uh ar-e-A-tuh), which causes patchy hair loss, scalp infections such as ringworm and a hair-pulling disorder called trichotillomania (trik-o-til-o-MAY-nee-uh).
Telogen effluvium - occurs mainly due to the body’s reaction to stress, brought about by, illnesses such as cancer, mental and emotional disturbances, medications such as blood thinners, hormonal imbalances, stress during childbirth and so on. In this condition hair thinning occurs on the scalp. The hair usually regrows after the stress period is over.