Lauren Bick is a 13-year-old girl who presents to her family physician's office with a 6-month history of weight loss. Her mother is concerned because she has noticed that Lauren has lost at least 10 pounds since her last doctor's visit which she had just before she started at her new school. Although Lauren has always been a "petite" girl, she is now the shortest in her class. The doctor asks Lauren's mom to give her a few minutes alone with Lauren. Once Lauren's mom has left the room, the doctor reviews the limits of confidentiality with Lauren and asks her about her weight loss. Lauren explains that she has met a new group of friends who do not believe that it is healthy to eat animals so she has joined them in following a vegan diet. She also reports that she's recently joined the long distance running club at her school. Lauren indicates that despite her mother's wishes, Lauren's goal is to get her weight down to 25 kg in the next few months. Lauren requests that you don't tell her mother this as it will likely cause them to argue. Lauren's menarche was at age 11 and she had been having regular menstrual periods but in the last 4 months, she has not had a period. Lauren indicates that she has not been sexually active. On questioning, she reports some constipation and says that she often feels cold.