WEIGHT LOSS

SHABANA YUSUF, MD AND PAMELA J. BAILEY, MD

INTRODUCTION

Unexplained weight loss in a child is always concerning for parents and may prompt a visit to the emergency department. The differential diagnosis of weight loss is vast and the emergency physician must have a methodical approach to its evaluation so that children with potentially life-threatening causes of weight loss can be promptly identified and treated. Most causes of weight loss in children are not immediate threats to life but still require thoughtful evaluation, appropriate referral, and good follow-up.

PATHOPHYSIOLOGY

The major determinants of body weight are water and the organic fuels, carbohydrates, protein, and fat. Normal body weight is maintained by a balanced intake of water, protein, carbohydrates, and fats. Weight loss occurs when the daily energy balance becomes negative for one of these components. By far, the most common cause of acute (less than 2 weeks) weight loss in children of any age is loss of water, usually associated with an acute infectious illness. In addition, most infectious illnesses in children are associated with anorexia and increased short-term metabolic demand. Chronic weight loss (occurring over more than 2 weeks) results when there is persistent insufficient intake and retention of protein and energy to meet cellular metabolic demands and tissue synthesis. Causes of chronic weight loss include decreased energy intake, normal energy intake with increased metabolic requirement, and normal energy intake in the face of malabsorption or impaired use.

Understanding the basic physiologic abnormalities that cause weight loss in children provides a general framework which allows the emergency physician to generate a very broad differential diagnosis (Table 79.1). These physiologic categories apply to children of all ages. The child’s age, severity and duration of the weight loss, specific symptoms and physical examination findings, as well as the judicious use of laboratory and radiographic studies help narrow the differential diagnosis into a more manageable list.

It is particularly important to recognize potentially life-threatening causes of weight loss in children in the emergency department (Table 79.2).

EVALUATION AND DECISION

General Approach

A thorough history and physical examination are key components in the evaluation of the patient with weight loss. Consideration of the child’s age and the severity and duration of the weight loss, along with the presence of other systemic symptoms and specific physical examination findings, refines the extensive differential diagnosis. Many diagnoses are exclusive to specific age groups. For the emergency physician, severity is an important consideration because sudden losses are more suggestive of life-threatening disorders that require prompt recognition and treatment. Acute weight loss is most often caused by anorexia, poor fluid and energy intake, increased losses, and increased metabolic need in association with an intercurrent illness. Weight loss is a sensitive indicator for dehydration and commonly occurs in the presence of any significant febrile illness. In this setting, the history includes an estimation of intake, losses, and increased need for fluid and energy intake. The types of losses (e.g., urine, stool, or emesis) may pinpoint the location of the pathology. Inborn errors of metabolism usually present as sepsis-like picture either in neonatal or infancy (see Chapter 103 Metabolic Emergencies). Patients can also present as hepatic and cardiac failure. Others may demonstrate a picture of chronic developmental and neurologic sequelae.

Chronic weight loss results from a combination of factors including anorexia, poor utilization or malabsorption, and increased requirements, as well as health consequences imposed by the underlying disease state. When considering the cause of chronic weight loss, broad categories exist, including loss (i) secondary to a medical cause (underlying infection, absorptive defect, inflammatory, or neoplastic disease); (ii) related to a psychosocial or psychiatric cause; or (iii) resulting as a consequence of both problems. Once again, the importance of a thorough history and physical examination cannot be overemphasized. A complete review of systems, in search of fever, night sweats, arthritis, abdominal pain, and/or diarrhea, dermatitis, and other constitutional symptoms, helps the physician reach the diagnosis (Table 79.3).

A complete and careful physical examination with weight, height for age, weight for height, vital signs, state of hydration, and findings suggestive of specific disease states (e.g., anomalies of the face, general appearance, hygiene, pallor, jaundice, murmur, and/or cyanosis, clubbing, lymphadenopathy, dermatitis, hyperpigmentation, abdominal mass and/or tenderness, oral ulcers, anal skin tags, arthritis, neurologic abnormalities) provide useful clues. The shape of the head is important and points to various syndromes. Nutritional inspection includes an evaluation of body fat, muscle mass, hair, skin, and nails. Physical signs associated with vitamin deficiencies are nonspecific and occur late in the course of malnutrition. Dysmorphic features should be noted and a thorough neurologic examination should be performed. Infants should be observed nursing or being bottle-fed, with attention to any gagging, choking, reflux, or respiratory distress. The assessment of the airway might be necessary to initiate a safe feeding plan.

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