CASE STUDY
You are a nurse on an inpatient psychiatric unit. J.M., a 23-year-old woman, was admitted to the psychiatric unit last night after assessment and treatment at a local hospital emergency department for "blacking out at school." She has been given a preliminary diagnosis of anorexia nervosa. As you begin to assess her, you notice that she has very loose clothing, she is wrapped in a blanket, and her extremities are very thin. She tells you, "I don't know why I'm here. They're making a big deal about nothing." She appears to be extremely thin and pale, with dry and brittle hair, which is very thin and patchy, and she constantly complains about being cold. As you ask questions about weight and nutrition, she becomes defensive and vague, but she does admit to losing "some" weight after an appendectomy 2 years ago. She tells you that she used to be fat, but after her surgery she did not feel like eating and everybody started commenting on how good she was beginning to look, so she just quit eating for a while. She informs you that she is eating lots now, even though everyone keeps "bugging me about my weight and how much I eat." She eventually admits to a weight loss of "about 40 pounds (18 kg) and I'm still fat."
Using Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V) criteria, how is the diagnosis of anorexia nervosa determined?