Anorexia

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[edit] Anorexia

Leonor Fernandez

Anorexia is a loss or decrease in appetite. The symptom of anorexia has been studied in the context of cancer, aging, and the human immunodeficiency virus (HIV), but most epidemiologic studies have focused on the clinical entity of weight loss rather than anorexia. It is therefore difficult to give an estimate of the prevalence of anorexia. In practice, anorexia is often associated with unintentional weight loss, and the evaluation may be approached similarly (see Chapter 25 ). This chapter highlights some unique aspects of the evaluation of anorexia.

The pathophysiology of anorexia is complex and incompletely understood. Several cytokines (e.g., interleukins 1 and 6, tumor necrosis factor-α) may mediate anorexia in cancer, HIV disease, and rheumatoid arthritis by acting on the hypothalamic feeding-associated sites.^[1][2] Some evidence indicates that anorexia may be adaptive in the short term with certain infections because it may serve to “starve” pathogens of nutrients.^[3] The anorexia-cachexia syndrome is associated with a variety of conditions, such as chronic pain, depression, anxiety, hypogeusia, hyposmia, early satiety, and iatrogenic factors (e.g., chemotherapy, radiotherapy).^[4] Aging often leads to a gradual decrease in appetite. This physiologic anorexia of aging is thought to result from a decrease in an opioid responsible for the feeding drive and an increase in the satiating effect of cholecystokinin.^[5]

[edit] History.

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When taking a history, the examiner should screen for several common conditions that may cause anorexia, including depression, anxiety, substance abuse (alcohol, intravenous drugs, and cocaine may lead to decreased appetite), and eating disorders, particularly in young women, athletes, dancers, and models, all known to be at increased risk for anorexia nervosa (see Chapter 55 ). Eliciting a fear of gaining weight or excessive worry about body fat may provide clues to eating disorders. A menstrual history is important in all women because amenorrhea often accompanies eating disorders and substantial weight loss. It is reasonable to assess HIV risk in all patients with anorexia.

Social factors that affect ability to eat should be evaluated, such as social isolation, lack of money, and physical impairments, since the patient or family may not always express the reasons for not eating. A thorough review of symptoms may be helpful, such as inquiring about fever, sweats, symptoms of hyperthyroidism and hypothyroidism, change in bowel habits or other gastrointestinal (GI) functions, and symptoms suggesting malignancy or neurologic disease. A travel history should be obtained to consider a variety of chronic infections. Medication use should be evaluated.

[edit] Physical Examination.

The patient's weight and body mass index (BMI) enable the physician and patient to document weight loss over time. The examiner should assess the most common sites of malignancy: lungs, breast, skin,

prostate, and colon. The lymph nodes and thyroid should also be assessed, with a check for hepatosplenomegaly, jaundice, or signs of central nervous system (CNS) dysfunction, including papilledema and dementia. The oral cavity should be examined to make sure no lesions or denture problems are causing difficulty eating. Patients with bulimia may have loss of tooth enamel.

[edit] Medications.

Drugs are a common cause of anorexia or dysgeusia (parageusia), and a trial of discontinuation should be considered. Culprits include sedatives, psychotropics, digoxin, appetite suppressants, interferon, thiazide diuretics, levodopa, narcotics, antibiotics, and chemotherapeutics.

[edit] Laboratory And Other Studies.

These are determined by the history but may reasonably include electrolytes, glucose, thyroid-stimulating hormone (TSH), calcium, liver function tests (LFTs, particularly albumin), and complete blood count (CBC). All these may not be necessary, however, if the anorexia is minimal or of recent onset. Few data indicate which studies are best. The patient with epidemiologic risk factors may have HIV serology. A Mini Nutritional Assessment may be used as a screening tool for early malnutrition in patients^[6] (Fig. 15-1). A chest radiograph may be considered to evaluate the possibility of lung cancer, tuberculosis, and abscess. All applicable screening tests (e.g., mammogram, Papanicolaou smear, sigmoidoscopy, colonoscopy) should be updated, especially if no cause is readily identified for the anorexia.

Figure 15-1 Mini Nutritional Assessment (MNA) form. (Courtesy Societé des Produits Nestlé SA, 1998.)

[edit] Age-Related Symptoms.

The physiologic (mild) anorexia of aging is partly related to the hypogeusia experienced with increasing age. The sense of smell is an integral part of the taste experience, and thus the decreased olfaction associated with chronic allergic rhinitis, smoking, advanced age, and rare neurologic problems may make food less desirable. Other chronic conditions, such as chronic pain, severe congestive heart failure, uremia, and respiratory failure, may also decrease interest in food.

[edit] Gastrointestinal Conditions.

GI malignancy may present with anorexia because of gastric outlet obstruction, intestinal obstruction, esophageal mass, or distant metastases. Other GI conditions that may cause anorexia include peptic ulcer disease, malabsorption, hepatitis, biliary disease, dysmotility, and oral cavity disease. Symptoms may guide the need for tests, such as stool for fat or parasites, sigmoidoscopy, endoscopy, radionuclide emptying scan, or upper GI series with small bowel follow-through. Hepatitis often causes dysgeusia in addition to decreased appetite.

[edit] Infections.

Patients with anorexia should be screened for HIV risk factors. Other infections to consider include tuberculosis, subacute bacterial endocarditis, parasitic infection, and abscess. Anorexia may occur in many acute infections, such as pneumonia, mononucleosis, and endocarditis, and is particularly common in viral hepatitis.

[edit] Malignancies.

Many malignancies may present with anorexia, especially those involving the GI tract. Renal cancer also may accompany this condition.

[edit] Endocrine Conditions.

Both hyperthyroidism and hypothyroidism may cause anorexia. One study on Graves' disease found that appetite decreased in 27% of hyperthyroid patients in their 70s.^[7] Other causes include markedhypercalcemia, uncontrolled diabetes, hyperparathyroidism, adrenal insufficiency, and panhypopituitarism. Diabetes may also cause delayed gastric emptying, which may occur with early satiety.

[edit] Neurologic Conditions.

Dementia and Parkinson's disease are often accompanied by decreased appetite. CNS tumors, especially those involving the hypothalamus, may present with anorexia.

[edit] Treatment.

Referral to a nutritionist may be helpful. Caloric supplements, enteral feeding, peripheral nutrition, and a variety of drugs (e.g., growth hormone, megestrol, cyproheptadine, tetrahydrocannabinol, anabolic steroids, prokinetic agents, antidepressants) are used with variable success (see Chapters 32 and 118 ). Contributing social and economic factors need to be addressed.

[edit] REFERENCES