Background
Anorexia is prolonged diminished appetite or appetite loss. This common symptom is to be differentiated from the eating disorder anorexia nervosa, which is often simply called anorexia. Anorexia may or may not be associated with weight loss. It is almost always a result of one or more underlying causes.
Pathophysiology
General mechanisms
Although the exact mechanisms by which the body regulates appetite and body weight have yet to be fully determined, modern research is providing more and more information on the subject. The hypothalamus is believed to regulate both satiety and hunger, leading to homeostasis of body weight in ideal situations. The hypothalamus interprets and integrates a number of neural and humoral inputs to coordinate feeding and energy expenditure in response to conditions of altered energy balance. Long-term signals communicating information about the body's energy stores, endocrine status, and general health are predominantly humoral. Short-term signals, including gut hormones and neural signals from higher brain centers and the gut, regulate meal initiation and termination. Hormones involved in this process include leptin, insulin, cholecystokinin, ghrelin, polypeptide YY, pancreatic polypeptide, glucagonlike peptide-1, and oxyntomodulin (1). Alterations in any of these humoral or neuronal processes can lead to anorexia.
Etiology
Pathologic causes may be acute, such as appendicitis or other surgical emergencies, or chronic, such as heart or renal failure or malignancies. Pathologic causes rarely present without other signs or symptoms in addition to anorexia.
Pharmacologic causes include substances taken and those recently discontinued. Substances of abuse, such as alcohol, tobacco, narcotics, marijuana, and stimulants, can affect appetite. Prescription and over-the-counter medications, as well as dietary supplements, can lead to anorexia.
Psychiatric illnesses are sometimes more difficult to find than the other categories, requiring time and a high index of suspicion. Anorexia may be the result of a primary eating disorder, such as anorexia nervosa, or other illnesses, such as depression, personality disorders, schizophrenia, and bipolar disorders .
Social factors often affect appetite. Bereavement, stress, and loneliness may cause anorexia. Moving from one's home, loss of ability to shop for food or prepare meals, and lack of finances may also result in appetite changes .
Evaluation
History
A careful history is key to determining the cause of anorexia in most patients.
History of present illness The first step is to understand the exact nature of the anorexia. Is the problem a loss of desire to eat or a loss of appetite with maintained desire? Is it truly associated with appetite, or is it related to early satiety, difficult or painful swallowing, abdominal symptoms that follow eating, loss of pleasure or satisfaction with eating, or loss of ability to prepare a meal? What does the patient think the underlying problem is? Are the symptoms constant or do they fluctuate? Are there any coexisting emotional problems? Has the patient lost weight, and if so, how much?
Past medical history Is there any history of previous eating disorders, psychiatric conditions, or chronic medical conditions?
Medications and habits What medications is the patient taking? What medications has the patient recently discontinued? Does the patient take any over-the-counter medications, dietary supplements, or herbal products? Does the patient use alcohol, tobacco, or illicit drugs?
Social history Eating is a very social function in most cultures. Stress, bereavement, troubles with relationships, loneliness, and guilt can all lead to anorexia. Who does the patient live with? Is food available in the home? Is the patient capable of shopping and preparing meals (e.g., mobility, vision, and cognitive capacity)? Are there financial concerns?
Review of systems A general review of systems should be performed, with focus on gastrointestinal (e.g., difficult or painful swallowing, nausea, abdominal pain or bloating, diarrhea or constipation, and rectal bleeding), psychiatric (e.g., depression and anxiety), and neurologic (e.g., mental status and recent head injury) systems. A diet history, either retrospective or prospective, through the use of a food diary, is often helpful.
Physical Examination
General appearance Does the patient look healthy or ill? Is there fever or tachycardia, suggestive of a systemic illness? Carefully measure the patient's weight and compare to previous recordings.
Head, eyes, ears, nose, and throat (HEENT) Look carefully for poor dentition, oral lesions, difficult swallowing, lymphadenopathy, and thyroid abnormalities.
Cardiorespiratory system Examine for arrhythmias, chronic obstructive pulmonary disease, and signs of heart failure, such as jugular venous distension or rales.
Gastrointestinal system Listen for abnormal bowel sounds. Examine for tenderness, rigidity, ascites, and hepatomegaly. Rectal examination, including guaiac testing, should be performed.
Skin Jaundice, skin tracks, cyanosis, lanugo, hyperpigmentation, and turgor should be noted.
Neurologic and psychological systems Examine the functions of cranial nerves, including smell and taste. Look for focal or generalized weakness, gait or balance disturbances, or movement disorders. Assess the patient's functional capacity and mental status. Assess for anxiety, depression, dementia, delirium, and psychosis.
Testing
As in all areas of medicine, diagnostic studies should be guided by the history and physical examination. Tests to consider in anorexia include a complete blood count, electrolytes panel, hepatic panel, and albumin. When assessing nutritional status, measuring prealbumin level may be preferred over albumin level in acute cases of anorexia because prealbumin is the earliest marker of changes in nutritional status (4,5). Chest x-ray and tuberculosis testing can be helpful in some cases, as might esophagogastroduodenoscopy, colonoscopy, and abdominal computed tomography or ultrasonography. Less commonly ordered tests include human immunodeficiency virus, thyroid-stimulating hormone and thyroid hormone, viral hepatitis panel, and urine protein, and testing for toxicology and drugs of abuse.
Diagnosis
Although the causes of anorexia are numerous and span the biopsychosocial spectrum, a thoughtful evaluation will generally reveal the underlying cause(s) of the loss of appetite, and specific interventions can then be instituted.
Anorexia is prolonged diminished appetite or appetite loss. This common symptom is to be differentiated from the eating disorder anorexia nervosa, which is often simply called anorexia. Anorexia may or may not be associated with weight loss. It is almost always a result of one or more underlying causes.
Pathophysiology
General mechanisms
Although the exact mechanisms by which the body regulates appetite and body weight have yet to be fully determined, modern research is providing more and more information on the subject. The hypothalamus is believed to regulate both satiety and hunger, leading to homeostasis of body weight in ideal situations. The hypothalamus interprets and integrates a number of neural and humoral inputs to coordinate feeding and energy expenditure in response to conditions of altered energy balance. Long-term signals communicating information about the body's energy stores, endocrine status, and general health are predominantly humoral. Short-term signals, including gut hormones and neural signals from higher brain centers and the gut, regulate meal initiation and termination. Hormones involved in this process include leptin, insulin, cholecystokinin, ghrelin, polypeptide YY, pancreatic polypeptide, glucagonlike peptide-1, and oxyntomodulin (1). Alterations in any of these humoral or neuronal processes can lead to anorexia.
Etiology
Pathologic causes may be acute, such as appendicitis or other surgical emergencies, or chronic, such as heart or renal failure or malignancies. Pathologic causes rarely present without other signs or symptoms in addition to anorexia.
Pharmacologic causes include substances taken and those recently discontinued. Substances of abuse, such as alcohol, tobacco, narcotics, marijuana, and stimulants, can affect appetite. Prescription and over-the-counter medications, as well as dietary supplements, can lead to anorexia.
Psychiatric illnesses are sometimes more difficult to find than the other categories, requiring time and a high index of suspicion. Anorexia may be the result of a primary eating disorder, such as anorexia nervosa, or other illnesses, such as depression, personality disorders, schizophrenia, and bipolar disorders .
Social factors often affect appetite. Bereavement, stress, and loneliness may cause anorexia. Moving from one's home, loss of ability to shop for food or prepare meals, and lack of finances may also result in appetite changes .
Evaluation
History
A careful history is key to determining the cause of anorexia in most patients.
History of present illness The first step is to understand the exact nature of the anorexia. Is the problem a loss of desire to eat or a loss of appetite with maintained desire? Is it truly associated with appetite, or is it related to early satiety, difficult or painful swallowing, abdominal symptoms that follow eating, loss of pleasure or satisfaction with eating, or loss of ability to prepare a meal? What does the patient think the underlying problem is? Are the symptoms constant or do they fluctuate? Are there any coexisting emotional problems? Has the patient lost weight, and if so, how much?
Past medical history Is there any history of previous eating disorders, psychiatric conditions, or chronic medical conditions?
Medications and habits What medications is the patient taking? What medications has the patient recently discontinued? Does the patient take any over-the-counter medications, dietary supplements, or herbal products? Does the patient use alcohol, tobacco, or illicit drugs?
Social history Eating is a very social function in most cultures. Stress, bereavement, troubles with relationships, loneliness, and guilt can all lead to anorexia. Who does the patient live with? Is food available in the home? Is the patient capable of shopping and preparing meals (e.g., mobility, vision, and cognitive capacity)? Are there financial concerns?
Review of systems A general review of systems should be performed, with focus on gastrointestinal (e.g., difficult or painful swallowing, nausea, abdominal pain or bloating, diarrhea or constipation, and rectal bleeding), psychiatric (e.g., depression and anxiety), and neurologic (e.g., mental status and recent head injury) systems. A diet history, either retrospective or prospective, through the use of a food diary, is often helpful.
Physical Examination
General appearance Does the patient look healthy or ill? Is there fever or tachycardia, suggestive of a systemic illness? Carefully measure the patient's weight and compare to previous recordings.
Head, eyes, ears, nose, and throat (HEENT) Look carefully for poor dentition, oral lesions, difficult swallowing, lymphadenopathy, and thyroid abnormalities.
Cardiorespiratory system Examine for arrhythmias, chronic obstructive pulmonary disease, and signs of heart failure, such as jugular venous distension or rales.
Gastrointestinal system Listen for abnormal bowel sounds. Examine for tenderness, rigidity, ascites, and hepatomegaly. Rectal examination, including guaiac testing, should be performed.
Skin Jaundice, skin tracks, cyanosis, lanugo, hyperpigmentation, and turgor should be noted.
Neurologic and psychological systems Examine the functions of cranial nerves, including smell and taste. Look for focal or generalized weakness, gait or balance disturbances, or movement disorders. Assess the patient's functional capacity and mental status. Assess for anxiety, depression, dementia, delirium, and psychosis.
Testing
As in all areas of medicine, diagnostic studies should be guided by the history and physical examination. Tests to consider in anorexia include a complete blood count, electrolytes panel, hepatic panel, and albumin. When assessing nutritional status, measuring prealbumin level may be preferred over albumin level in acute cases of anorexia because prealbumin is the earliest marker of changes in nutritional status (4,5). Chest x-ray and tuberculosis testing can be helpful in some cases, as might esophagogastroduodenoscopy, colonoscopy, and abdominal computed tomography or ultrasonography. Less commonly ordered tests include human immunodeficiency virus, thyroid-stimulating hormone and thyroid hormone, viral hepatitis panel, and urine protein, and testing for toxicology and drugs of abuse.
Diagnosis
Although the causes of anorexia are numerous and span the biopsychosocial spectrum, a thoughtful evaluation will generally reveal the underlying cause(s) of the loss of appetite, and specific interventions can then be instituted.
