Anorexia nervosa is a severe life-threatening eating disorder characterized by individuals purposefully abstain from eating and exercises for many hours to lose weight because they believe they are overweight (Abu-Baker & Alshdefat, 2020). Incidence and Prevalence Approximately 3.4 million young people throughout the world have anorexia nervosa. In the United States (US), the prevalence among females is of one out of 200. Anorexia nervosa is common among young women and adolescents. However, the disorder is increasingly seen among boys, men, and women older than 40 (Abu-Baker et al., 2020). Anorexia nervosa peaked from the mid-20th century, and the highest incident is reported among females between the ages of 12 and 18 years old. People who are considered in the higher socioeconomic classes have the highest number of anorexia nervosa. It is the third prevalent chronic disease among adolescents. The prevalence rate is 3% in female adolescents. The mortality rate linked with anorexia nervosa is higher than any other psychiatric disorder, which is around 4.0%. The highest causes of death are due to suicide, multisystem organ complications, and substance abuse (Abu-Baker et al., 2020; Valderas Martinez et al., 2019). Pathophysiology Individuals who are on weight loss and strict diet plan only might not develop anorexia nervosa (Abu-Baker et al., 2020). However, a small number of people might get to that point after a long period of being on their plan (Abu-Baker et al., 2020). Research showed moderate biological vulnerabilities to anorexia nervosa from genetic effects. Genetic effects count for about 56%, environmental effects 35%, and family environments such as pressuring children to be at the top of their class or abusive parents account about 5%. Serotonin and neurotrophic abnormalities have been linked to eating disorders such as anorexia nervosa. Also, individuals with anorexia nervosa presented with remarkable hyperactivity in the amygdala that led to negative emotions (Selby & Coniglio, 2020). Cardiovascular Anorexia nervosa patients who lost significant weight eventually end up with left ventricular atrophy as explained by the left ventricular mass index, and decline in chamber dimensions, as well as the left ventricle and left atrium (Sachs, Harnke, Mehler, & Krantz, 2016). Because of these changes and low blood volume in the heart chamber, mitral valve prolapse occurs in spite of the lack of intrinsic myxomatous valvular degeneration. At the same time, low voltage of ST depression, falt T-wave, and prolonged QT intervals have been detected in echocardiographic measurements. However, recent research showed that anorexia nervosa might not necessarily be connected with prolonged QT intervals. Instead, when providers see it on an electrocardiogram, it should alarm the provider to investigate for secondary causes such as differences in electrolytes serum levels such as sodium and magnesium or from medications that can prolong the QT interval (Sachs, Harnke, Mehler, & Krantz, 2016). Endocrine and Metabolic Patients who present with severe starvation and deprivation will have endocrine abnormalities except for elevated levels of peptide YY (Schorr & Miller, 2017). Commonly, the disorder causes hypothalamic amenorrhea, reduced gonadotrophin-releasing hormone (GnRH), luteinizing hormone (LH), low estradiol, and testosterone levels. The resistance of growth hormone is developed, which leads to an increase in the growth hormone and a decrease in the systemic insulin-like growth factor 1 (IGF1) levels. The low levels of IGF1 perhaps an adaptive response to reduce energy on the growth during chronic starvation (Schorr & Miller, 2017). Gastrointestinal Dieting for an extended period leads to the dysfunction of gastrointestinal organs, which leads patients to begin complaining of digestive illnesses. Some of these illnesses are fullness after eating lunch or dinner, constipation, epigastric pain or discomfort, dysphagia, and nausea. These symptoms may present mildly, but these signs can lead to severe complications, which may require surgical intervention. Patients will also complain of dry mouth, issues with foul mouth smell, and decrease in saliva production. Anorexia nervosa patients have much lower rate of stomach emptying compare to healthy individuals. This condition is referred to as gastroparesis (Malczyk & Oświęcimska, 2017). Physical Assessment and Exam Patient who present with anorexia nervosa are more likely will deny that they are ill but their skinny and weak appearance is evident. Patients will deny that they are hungry or report any weight loss. However, patients usually report that they have abdominal discomfort, full after eating small meals, bloating, and unable to fall asleep. On physical examination, bradycardia, brittle hair and nails, thin body, hypotension, paleness, dryness, lanugo, edema, dental erosions from acid reflux, and marked weight loss compare with age presented (Harrington, Jimerson, Haxton, & Jimerson, 2015). Diagnostics DSM-5 Criteria Providers can diagnose anorexia nervosa by using the DSM-5 diagnostic criteria. The criteria are divided into A, B, and C as follow: A. Restriction of energy intake relative to requirements, leading to a significantly low body weight in the context of age, sex, developmental trajectory, and physical health. Significantly low weight is defined as a weight that is less than minimally normal or, for children and adolescents, less than that minimally expected. B. Intense fear of gaining weight or of becoming fat, or persistent behavior that interferes with weight gain, even though at a significantly low weight. C. Disturbance in the way in which one's body weight or shape is experienced, undue influence of body weight or shape on self-evaluation, or persistent lack of recognition of the seriousness of the current low body weight. Laboratory Testing Due to the volume loss and body waste from starvation, providers must order specific gravity for hydration status, pH, ketones, and erythrocyte sedimentation rate. Vital signs such as weight, height, body mass index, and body temperature must be included to help setting up the treatment plan. Also, urinalysis with specific gravity, complete blood count, complete metabolic panel, amylase and lipase measurement, phosphorous and magnesium measurement, and thyroid function tests such as thyroid-stimulating hormone, thyroxine, and free triiodothyronine. Providers may also order bone mineral density testing if patient has been dieting for greater than six months (Harrington et al., 2015). Evidence-Based Treatment Plan A treatment plan is a multiteam approach due to the nature of the disorder. A psychotherapist or psychiatrist is typically included in the plan of care. Eating disorder specialists, usually with qualifications and background in psychiatry or adolescent med icine, are impeccably engaged yet may not be accessible in some areas. A dietitian can assist select nutritious and calorie-rich foods. For teens, it is important to include their schoolteachers and administration. Most states require formal 504 plans that point out appropriate accommodations, such as mini-breaks for snacks during class time or provide those in need to miss school for rehabilitation so they can have an equal educational opportunity similar to their peers. Treatment success may depend on placing a therapeutic partnership with the patient, the patient's family, and collaboration with all the treatment team onboard or involved in the treatment plan (Harrington et al., 2015). An essential part of the treatment plan is setting goals with the patient. Patients with anorexia nervosa may only consume 500 calories a day. However, daily average adolescent caloric intake is usually 1,800 for females and 2,220 for males. The target weight gain in the initial stages is 90% of the average weight based on the patient's height, age, and sex. The provider must use the growth chart to keep track of the patient's weight gain changes. Also, the patient’s provider must set goals such as agreeing on the weekly exercise plan based on the weight gain, minimum acceptable weight gain, compliance with seeing either a psychiatric or a psychologist, nutrition goals, and antidepressant medications such as selective serotonin reuptake inhibitors (SSRIs) which it may help alleviate symptoms of depression and suicidal ideation in patients with anorexia nervosa (Harrington et al., 2015). Patient Education Providers must educate their patients about the essential impact of the disorder and its complications on their health. An explanation about the relationship between anorexia nervosa, chronic symptoms, laboratory abnormalities, and the density of their bone must be explained in detail (Abu-Baker et al., 2020; Harrington et al., 2015). Patients must be reminded about visiting their dentist to prevent dental erosions and other dental disease due to anorexia. They should be told to wear clothing that can fit them instead of wearing multiple layers to eliminate the feeling of being overweight. Eating healthy balanced meals from all food groups is critical for their reconstruction for their body and replenish from the inside out (Abu-Baker et al., 2020; Silverstein, Haggerty, Sams, Phillips, & Roberts, 2019). Patient must be assured that eating food does not cause gastroparesis; their symptoms will resolve over four to six weeks when they follow the plan of care. Reassure patients that constipation will resolve in few weeks after they return to their normal weight. Follow up and evaluation Follow up and evaluation is based on the care plan that is put forward by the multidisciplinary team caring for the patient with anorexia nervosa. Initially, the goal is to make decisions on short-term risk involved by making the assessment of the physical risk and the patient’s psychological capacity to consent to the treatment by the multidisciplinary team. A referral to an eating disorder program is a must and should be discussed with patient and family (Abu-Baker et al., 2020; Harrington et al., 2015; Silverstein et al., 2019). Hospitalizations can be discussed as well in certain cases. Visits with an outpatient dietitian can be helpful in maintaining nutrition recovery. The dietitian follow-up can help with strengthening of behaviors that can support the eating habits, monitor body weight, and body needs during the treatment plan. Treatment evaluation is not all about consuming food but following up with psychiatrist or psychologist especially if antidepressant medications have been prescribed is imperative (Abu-Baker et al., 2020; Harrington et al., 2015; Silverstein et al., 2019). References Abu-Baker, R., & Alshdefat, A. (2020). Family therapy for adolescent with anorexia nervosa – A literature review. Drug Invention Today, 14(4), 648–651. Retrieved from https://eds-bebscohostcom.libauth.purdueglobal.edu/eds/pdfviewer/pdfviewer?vid=4&sid=238a51a6-f3134021-a378-6070aed1d54a%40pdc-v-sessmgr03 Harrington, B. C., Jimerson, M., Haxton, C., & Jimerson, D. C. (2015). Initial evaluation, diagnosis, and treatment of anorexia nervosa and bulimia nervosa. American Family Physician, 91(1), 46-52. Retrieved from https://www.aafp.org/afp/2015/0101/p46.html Malczyk, Ż., & Oświęcimska, J. M. (2017). Gastrointestinal complications and refeeding guidelines in patients with anorexia nervosa. Psychiatria Polska, 51(2), 219–229. https://doi.org/10.12740/PP/65274 Sachs, K. V., Harnke, B., Mehler, P. S., & Krantz, M. J. (2016). Cardiovascular complications of anorexia nervosa: A systematic review. International Journal of Eating Disorders, 49(3), 238–248. https://doi.org/10.1002/eat.22481 Schorr, M., & Miller, K. K. (2017). The endocrine manifestations of anorexia nervosa: mechanisms and management. Nature reviews. Endocrinology, 13(3), 174–186. https://doi.org/10.1038/nrendo.2016.175 Selby, E. A., & Coniglio, K. A. (2020). Positive emotion and motivational dynamics in anorexia nervosa: A positive emotion amplification model (PE-AMP). Psychological Review. https://doi.org/10.1037/rev0000198 Silverstein, L. S., Haggerty, C., Sams, L., Phillips, C., & Roberts, M. W. (2019). Impact of an oral health education intervention among a group of patients with eating disorders (anorexia nervosa and bulimia nervosa). Journal of Eating Disorders, 7(1), 29. Retrieved from https://link.springer.com/article/10.1186/s40337-019-0259-x#citeas