PCOS, or polycystic ovarian syndrome, is an endocrine disorder caused by an increase of androgens (male hormones) in the female body. PCOS can be difficult to diagnose–and even more difficult to treat. The cause of PCOS is varied and somewhat mysterious as well. Researchers believe that genetics and environmental factors play a part. Hallmark symptoms include an increase in body hair, irregular menstrual cycles, weight gain, and acne.