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KembaraXtra-Medicine- Anorexia Nervosa
Basic Information and Definition
Anorexia nervosa is a serious psychiatric disorder characterized by abnormal eating behaviors, intense fear of weight gain, severe self-induced weight loss, and a distinct disturbance in body image and self-perception. The disorder involves both psychological and physiological components and can affect nearly every organ system. It is classified into restricting type and binge-eating/purging type. ICD-10-CM codes include F50.00 (unspecified), F50.01 (restricting type), and F50.02 (binge-eating/purging type).
Epidemiology and Demographics
In the United States, anorexia nervosa affects approximately 0.2% to 1.3% of the general population, with an annual incidence of 5 to 10 cases per 100,000 individuals. The disorder is strongly associated with activities that emphasize thinness, such as competitive athletics and modeling. Females are disproportionately affected, with a female-to-male ratio of approximately 20:1. About 0.5% to 1% of women aged 15 to 30 years and up to 1.5% of teenage girls are affected. Adolescence to young adulthood is the most common age of onset, with a mean onset around 17 years.
Physical Findings and Clinical Presentation
Eating disorders can present with subtle, nonspecific symptoms in early or mild cases, including fatigue, cold intolerance, dizziness, and low energy, making early recognition challenging. Children and adolescents are particularly vulnerable due to ongoing growth and development. In moderate to severe anorexia nervosa, patients often appear markedly emaciated and may wear layered clothing to conceal weight loss. The skin is typically dry, may exhibit lanugo hair, and can appear yellowish due to carotenodermia. Hair thinning, brittle nails, bradycardia, hypotension, hypothermia, and bradypnea are common. Peripheral edema may occur. In females, normal fat distribution is lost, although axillary and pubic hair are usually preserved.
Etiology and Pathophysiology
The etiology of anorexia nervosa is multifactorial and incompletely understood, involving sociocultural pressures, psychological vulnerabilities, familial dynamics, and genetic predisposition. A history of sexual abuse has been reported in up to half of affected individuals. Psychologically, patients often struggle with low self-esteem, impaired identity formation, and a strong need for control. Body weight and food intake may become central mechanisms through which individuals attempt to exert control over their environment and emotions.
Diagnostic Criteria
Diagnosis is based on clinical assessment and DSM-5 criteria. These include restriction of energy intake leading to significantly low body weight for age, sex, and developmental stage; intense fear of gaining weight or persistent behavior interfering with weight gain; and disturbance in body image or lack of recognition of the seriousness of low body weight. Subtypes include the restricting type, characterized by dieting, fasting, or excessive exercise without bingeing or purging, and the binge-eating/purging type, which includes recurrent binge eating or purging behaviors. Amenorrhea, although historically emphasized, may be absent in younger adolescents and is no longer required for diagnosis.
Differential Diagnosis
Conditions that may mimic or coexist with anorexia nervosa include other eating disorders such as bulimia nervosa and binge eating disorder, substance use disorders, major depressive disorder, obsessive-compulsive disorder, schizophrenia, and conversion disorder. Medical causes of weight loss must also be considered, including malignancy, endocrine disorders (such as Addison disease, diabetes mellitus, thyroid disorders, or panhypopituitarism), gastrointestinal diseases (celiac disease, Crohn disease, parasitic infections), and chronic infections such as tuberculosis or HIV.
Workup and Screening
Screening for eating disorders should be incorporated into routine psychosocial assessments, especially in adolescents. Patients may minimize symptoms; therefore, collateral history from parents or caregivers is essential. The SCOFF questionnaire is a useful screening tool, with high sensitivity for anorexia and bulimia when two or more responses are positive. Baseline electrocardiography is recommended for all patients to assess for QT interval prolongation, which is associated with increased risk of sudden cardiac death. A dual-energy x-ray absorptiometry (DEXA) scan should be considered after six months of amenorrhea to evaluate for osteopenia or osteoporosis.
Laboratory Findings
Laboratory results may be normal in mild cases. Common abnormalities include endocrine changes such as decreased gonadotropins, estrogens, and thyroid hormones, with normal thyroid-stimulating hormone and elevated cortisol. Hematologic abnormalities may include leukopenia, anemia, thrombocytopenia, and reduced inflammatory markers. Electrolyte disturbances such as hypokalemia, hypomagnesemia, hypocalcemia, hypophosphatemia, metabolic alkalosis, and hypercholesterolemia may occur. Elevated plasma beta-carotene levels can help distinguish anorexia nervosa from other causes of starvation.
Treatment and Nonpharmacologic Management
Management requires a multidisciplinary approach involving medical, nutritional, and psychological care. A target weight should be established, aiming for 100% of ideal body weight in adolescents and 90% to 100% in adults. Weight restoration should proceed gradually, with initial caloric intake of 800 to 1200 kcal per day in small, frequent meals, advancing to 1500 to 3000 kcal as tolerated. Electrolytes must be monitored closely to prevent refeeding syndrome. In severe cases, enteral or parenteral nutrition may be necessary. Mealtimes should emphasize support rather than confrontation, and post-meal supervision may be required to prevent purging or excessive exercise.
Acute Management and Severity Assessment
Severity is categorized by body mass index in adults or BMI percentile in children and adolescents. Mild disease corresponds to a BMI of 17 kg/m² or higher, moderate disease to BMI 16–16.99, severe disease to BMI 15–15.99, and extreme disease to BMI below 15. Most patients can be managed as outpatients; however, inpatient care is indicated for medical instability, severe electrolyte disturbances, significant bradycardia or hypotension, prolonged QT interval, rapid weight loss, failure of outpatient treatment, or suicidal ideation. Pharmacologic therapy generally has limited benefit unless comorbid depression, anxiety, or obsessive-compulsive symptoms are present.
Chronic Management and Psychotherapy
Long-term psychotherapy is central to recovery and may need to continue for years. Treatment focuses on body image, self-esteem, interpersonal relationships, and relapse prevention. Family-based therapy is particularly effective in children and adolescents and is strongly recommended.
Disposition and Prognosis
The long-term prognosis of anorexia nervosa is guarded, with many patients experiencing relapses or persistent disordered eating and body image distortion. Menstrual function typically returns within six months of achieving 90% of ideal body weight, although pregnancy can occur even in the presence of amenorrhea. Mortality rates range from 5% to 20%, significantly higher than in age-matched peers, with common causes including electrolyte imbalance, starvation, and suicide. Favorable prognostic factors include early diagnosis, prompt treatment initiation, strong family support, and positive therapeutic relationships.
Referral and Indications for Hospitalization
Hospitalization should be considered for severe dehydration, electrolyte abnormalities, cardiac arrhythmias, significant physiologic instability, intractable purging, suicidal thoughts, weight loss exceeding 30% of ideal body weight, rapid ongoing weight loss, or failure of outpatient nutritional rehabilitation. Early involvement of mental health specialists is essential to optimize outcomes.
Basic Information and Definition
Anorexia nervosa is a serious psychiatric disorder characterized by abnormal eating behaviors, intense fear of weight gain, severe self-induced weight loss, and a distinct disturbance in body image and self-perception. The disorder involves both psychological and physiological components and can affect nearly every organ system. It is classified into restricting type and binge-eating/purging type. ICD-10-CM codes include F50.00 (unspecified), F50.01 (restricting type), and F50.02 (binge-eating/purging type).
Epidemiology and Demographics
In the United States, anorexia nervosa affects approximately 0.2% to 1.3% of the general population, with an annual incidence of 5 to 10 cases per 100,000 individuals. The disorder is strongly associated with activities that emphasize thinness, such as competitive athletics and modeling. Females are disproportionately affected, with a female-to-male ratio of approximately 20:1. About 0.5% to 1% of women aged 15 to 30 years and up to 1.5% of teenage girls are affected. Adolescence to young adulthood is the most common age of onset, with a mean onset around 17 years.
Physical Findings and Clinical Presentation
Eating disorders can present with subtle, nonspecific symptoms in early or mild cases, including fatigue, cold intolerance, dizziness, and low energy, making early recognition challenging. Children and adolescents are particularly vulnerable due to ongoing growth and development. In moderate to severe anorexia nervosa, patients often appear markedly emaciated and may wear layered clothing to conceal weight loss. The skin is typically dry, may exhibit lanugo hair, and can appear yellowish due to carotenodermia. Hair thinning, brittle nails, bradycardia, hypotension, hypothermia, and bradypnea are common. Peripheral edema may occur. In females, normal fat distribution is lost, although axillary and pubic hair are usually preserved.
Etiology and Pathophysiology
The etiology of anorexia nervosa is multifactorial and incompletely understood, involving sociocultural pressures, psychological vulnerabilities, familial dynamics, and genetic predisposition. A history of sexual abuse has been reported in up to half of affected individuals. Psychologically, patients often struggle with low self-esteem, impaired identity formation, and a strong need for control. Body weight and food intake may become central mechanisms through which individuals attempt to exert control over their environment and emotions.
Diagnostic Criteria
Diagnosis is based on clinical assessment and DSM-5 criteria. These include restriction of energy intake leading to significantly low body weight for age, sex, and developmental stage; intense fear of gaining weight or persistent behavior interfering with weight gain; and disturbance in body image or lack of recognition of the seriousness of low body weight. Subtypes include the restricting type, characterized by dieting, fasting, or excessive exercise without bingeing or purging, and the binge-eating/purging type, which includes recurrent binge eating or purging behaviors. Amenorrhea, although historically emphasized, may be absent in younger adolescents and is no longer required for diagnosis.
Differential Diagnosis
Conditions that may mimic or coexist with anorexia nervosa include other eating disorders such as bulimia nervosa and binge eating disorder, substance use disorders, major depressive disorder, obsessive-compulsive disorder, schizophrenia, and conversion disorder. Medical causes of weight loss must also be considered, including malignancy, endocrine disorders (such as Addison disease, diabetes mellitus, thyroid disorders, or panhypopituitarism), gastrointestinal diseases (celiac disease, Crohn disease, parasitic infections), and chronic infections such as tuberculosis or HIV.
Workup and Screening
Screening for eating disorders should be incorporated into routine psychosocial assessments, especially in adolescents. Patients may minimize symptoms; therefore, collateral history from parents or caregivers is essential. The SCOFF questionnaire is a useful screening tool, with high sensitivity for anorexia and bulimia when two or more responses are positive. Baseline electrocardiography is recommended for all patients to assess for QT interval prolongation, which is associated with increased risk of sudden cardiac death. A dual-energy x-ray absorptiometry (DEXA) scan should be considered after six months of amenorrhea to evaluate for osteopenia or osteoporosis.
Laboratory Findings
Laboratory results may be normal in mild cases. Common abnormalities include endocrine changes such as decreased gonadotropins, estrogens, and thyroid hormones, with normal thyroid-stimulating hormone and elevated cortisol. Hematologic abnormalities may include leukopenia, anemia, thrombocytopenia, and reduced inflammatory markers. Electrolyte disturbances such as hypokalemia, hypomagnesemia, hypocalcemia, hypophosphatemia, metabolic alkalosis, and hypercholesterolemia may occur. Elevated plasma beta-carotene levels can help distinguish anorexia nervosa from other causes of starvation.
Treatment and Nonpharmacologic Management
Management requires a multidisciplinary approach involving medical, nutritional, and psychological care. A target weight should be established, aiming for 100% of ideal body weight in adolescents and 90% to 100% in adults. Weight restoration should proceed gradually, with initial caloric intake of 800 to 1200 kcal per day in small, frequent meals, advancing to 1500 to 3000 kcal as tolerated. Electrolytes must be monitored closely to prevent refeeding syndrome. In severe cases, enteral or parenteral nutrition may be necessary. Mealtimes should emphasize support rather than confrontation, and post-meal supervision may be required to prevent purging or excessive exercise.
Acute Management and Severity Assessment
Severity is categorized by body mass index in adults or BMI percentile in children and adolescents. Mild disease corresponds to a BMI of 17 kg/m² or higher, moderate disease to BMI 16–16.99, severe disease to BMI 15–15.99, and extreme disease to BMI below 15. Most patients can be managed as outpatients; however, inpatient care is indicated for medical instability, severe electrolyte disturbances, significant bradycardia or hypotension, prolonged QT interval, rapid weight loss, failure of outpatient treatment, or suicidal ideation. Pharmacologic therapy generally has limited benefit unless comorbid depression, anxiety, or obsessive-compulsive symptoms are present.
Chronic Management and Psychotherapy
Long-term psychotherapy is central to recovery and may need to continue for years. Treatment focuses on body image, self-esteem, interpersonal relationships, and relapse prevention. Family-based therapy is particularly effective in children and adolescents and is strongly recommended.
Disposition and Prognosis
The long-term prognosis of anorexia nervosa is guarded, with many patients experiencing relapses or persistent disordered eating and body image distortion. Menstrual function typically returns within six months of achieving 90% of ideal body weight, although pregnancy can occur even in the presence of amenorrhea. Mortality rates range from 5% to 20%, significantly higher than in age-matched peers, with common causes including electrolyte imbalance, starvation, and suicide. Favorable prognostic factors include early diagnosis, prompt treatment initiation, strong family support, and positive therapeutic relationships.
Referral and Indications for Hospitalization
Hospitalization should be considered for severe dehydration, electrolyte abnormalities, cardiac arrhythmias, significant physiologic instability, intractable purging, suicidal thoughts, weight loss exceeding 30% of ideal body weight, rapid ongoing weight loss, or failure of outpatient nutritional rehabilitation. Early involvement of mental health specialists is essential to optimize outcomes.
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