USMLE Guide: Anorexia Nervosa

Introduction

Anorexia Nervosa is an eating disorder characterized by an intense fear of gaining weight and a distorted body image, leading to extreme food restriction and self-starvation. This USMLE guide aims to provide a comprehensive overview of Anorexia Nervosa, including its epidemiology, clinical presentation, diagnostic criteria, complications, and management.

Epidemiology

• Anorexia Nervosa primarily affects adolescent and young adult females.
• Lifetime prevalence is estimated to be around 0.9% in females and 0.3% in males.
• More common in Western societies and urban areas.

Clinical Presentation

• Intense fear of gaining weight or becoming fat, despite being underweight.
• Distorted body image and self-esteem excessively influenced by body weight and shape.
• Restriction of food intake leading to significantly low body weight.
• Amenorrhea (cessation of menstruation) in females.
• Psychological symptoms such as anxiety, depression, and obsessive-compulsive behaviors.

Diagnostic Criteria

To diagnose Anorexia Nervosa, the following criteria must be met:

1. Restriction of energy intake leading to significantly low body weight.
2. Intense fear of gaining weight or becoming fat, even when underweight.
3. Distorted body image, undue influence of body weight/shape on self-esteem.
4. Amenorrhea for at least three consecutive cycles (in post-menarcheal females).

Complications

• Electrolyte imbalances, especially hypokalemia, can lead to cardiac arrhythmias.
• Starvation can cause multiple organ dysfunction and impaired immune function.
• Osteoporosis and increased risk of fractures due to bone mineral density loss.
• Gastrointestinal complications, including constipation and gastroparesis.
• Psychological complications such as depression, anxiety disorders, and social isolation.

Management

1. Medical Stabilization:

   • Hospitalization for severe cases (e.g., BMI < 15 kg/m² or unstable vital signs).
   • Correct electrolyte imbalances, provide nutritional support, and monitor organ function.
   • Address any acute medical complications or psychiatric emergencies.

2. Nutritional Rehabilitation:

   • Collaborate with a registered dietitian to develop an appropriate meal plan.
   • Gradual reintroduction of calories to restore weight and improve nutritional status.
   • Regular monitoring of weight, vital signs, and laboratory parameters.

3. Psychological Interventions:

   • Individual therapy, such as cognitive-behavioral therapy (CBT), to address distorted body image, anxiety, and maladaptive thoughts.
   • Family-based therapy (FBT) for adolescents involving the family in the recovery process.
   • Supportive psychotherapy to provide empathy, validation, and emotional support.

4. Pharmacotherapy:

   • Selective serotonin reuptake inhibitors (SSRIs) for associated depression and anxiety disorders.
   • No specific medication for Anorexia Nervosa itself, but medications may be used to manage comorbid conditions.

Conclusion

Anorexia Nervosa is a serious eating disorder characterized by extreme food restriction, fear of weight gain, and distorted body image. Recognizing the clinical presentation, understanding the diagnostic criteria, and addressing the potential complications are essential for effective management. Combining medical stabilization, nutritional rehabilitation, psychological interventions, and, if necessary, pharmacotherapy can help individuals with Anorexia Nervosa achieve recovery and improved overall health.