Snapshot A 17-year-old girl presents to your office for an annual sports physical. She is an accomplished varsity athlete on her high school cross-country team and feels significant pressure to set a school record during her final season. She does not bring up any health issues that are of concern to her, but upon questioning, she admits that she has not menstruated for 5 months. Her BMI is 15 kg/m2. Introduction Overview anorexia nervosa is an eating disorder characterized by an extreme fear of weight gain, behavioral and dietary habits that prevent weight gain, and an altered perception of one's body weight Epidemiology Prevalence 0.3-1% overall in the US as high as 4% among women Demographics female:male ratio 10-20:1 most prevalent in pubertal and adolescent girls majority have onset between ages 13-18 years Risk factors female family history of eating disorders low self-esteem ETIOLOGY Pathophysiology result of a complex of psychosocial factors Presentation Symptoms anxiety depression negative self image amenorrhea irritability constipation dry skin hair loss fainting or dizziness lethargy Physical exam low BMI (< 18.5 kg/m2) hypotension bradycardia hypothermia dry skin lanugo peripheral edema loss of muscle mass Studies Serum labs complete blood count may show leukopenia and thrombocytopenia basic metabolic panel may show electrolyte abnormalities in severe disease EKG may show evidence of sinus bradycardia QT-interval prolongation indicates serious risk for cardiac arrhythmias Tested Differential Hyperthyroidism key distinguishing factor abnormal thyroid hormone levels Celiac disease key distinguishing factor intolerance to gluten-containing foods Treatment Lifestyle psychological/behavioral therapy & nutritional rehabilitation indications BMI > 14.5 kg/mm2 mild electrolyte imbalances technique vitamin supplementation with calcium monitor for refeeding syndrome, a possible complication that leads to electrolyte and fluid imbalances labs: hypophosphatemia, hypokalemia, hypomagnesemia Medical estrogen replacement (e.g. oral contraceptives) indications treatment of osteopenia associated with anorexia hospital admission with inpatient treatment indications BMI < 14.5 kg/mm2 severe electrolyte imbalances Complications Malnutrition Delayed puberty Amenorrhea Arrested growth Osteoporosis Electrolyte imbalances Cardiovascular effects cardiomyopathy long QT sndrome bradycardia Prognosis Morbidity 10-20% About 50% of patients make a complete recovery Worse prognosis for patients who are older (> 18 years of age) at age of onset of the disorder as well as patients with an onset before 11 years of age