RETN and polycystic ovary syndrome: For resistin, there were 20 studies comparing circulating resistin in healthy non-obese PCOS women vs. non-obese control, 12 studies on obese PCOS vs. obese healthy women, and 18 studies on obese PCOS vs. non-obese PCOS patients [7, 9, 30, 32–34, 36–39, 44, 51, 53–55, 59–61].