Poor Weight Gain

Karen A. Francolla and Praveen S. Goday

Failure to thrive describes the condition of infants and toddlers under age 3 years who have an abnormally low weight for their age and sex. With prolonged and/or severe malnutrition, stature and head circumference can be secondarily affected. The prevalence of failure to thrive is reported to be 10% to 20% of all children treated in ambulatory care centers and up to 5% of all referrals to pediatric hospitals.¹ Regardless of specific etiology, failure to thrive may have profound effects on the growing child, including persistent short stature, decreased resistance to infection, and possible developmental impairment and/or disabilities.^2,3

DEFINITION

Failure to thrive is characterized by insufficient growth recognized by the observation of growth over time using standard growth curves. This entity is also called failure to gain weight, growth failure, and growth faltering. There is a lack of consensus regarding the specific anthropometric criteria required to classify a child as failure to thrive. Thus, many “definitions” for failure to thrive are commonly used. These include: weight less than 3rd percentile, weight-for-height less than 5th percentile, or downward crossing of 2 or more major percentiles on the growth chart.

PATHOGENESIS

Three basic mechanisms underlie failure to thrive: (1) inadequate caloric intake, (2) insufficient utilization or absorption of consumed calories, and (3) increased metabolic requirements. There are numerous specific etiologies for failure to thrive (see Table 30.1). However, most commonly, failure to thrive results from insufficient caloric intake due to either lack of food or feeding and/or behavioral problems that limit a child’s intake. In many cases, a specific organic etiology for a child’s failure to thrive is never identified, and when one is, it rarely presents with growth failure in isolation. Behavioral and psychosocial feeding problems are common and should not be thought of as diagnoses of exclusion.

Table 30-1. Major Etiologies of Failure to Thrive

CONTRIBUTORY FACTORS

Prematurity and low birth weight likely are risk factors for the development of feeding problems.⁴ Other known risk factors for this type of failure to thrive can be thought of as infant-, maternal-, or family-related and include chronic diseases, malabsorption, lack of maternal support and/or education, and lower income and access to food (see Table 30.2). Poverty is the single largest risk factor for failure to thrive.

Difficulty in establishing breast-feeding or bottle-feeding in infancy can be due to underlying medical problems that impact upon feeding, and this can lead to dysfunctional maternal-child bonding. Resultant disruption of the mutually rewarding parent-child relationship then may negatively affect the child’s mealtime behavior and consequently the child’s food intake. Weaning is a prime time for the emergence of problems with failure to thrive.⁵ It is at this time that a child’s oral motor skills have developed to allow the consumption of more solid textures. For some children, food refusal for new textures and/or solids leads to inadequate calorie consumption. The reasons for this failure to feed are myriad and are further discussed in Chapter 31.

Psychological factors should be screened for since these can contribute to a child’s failure to thrive. These include poor parenting, lack of child-parent attachment, low socioeconomic standing, and neglect and/or abuse. These problems may arise in the presence of poor social supports and mental illness.⁶ Younger maternal age is also a risk factor for failure to thrive. Suspicion of neglect and/or abuse should be promptly reported to local child protective services.

EVALUATION

A thorough patient history, physical examination, and review of past and present growth data are the first steps in the evaluation of failure to thrive (see Table 30.3). Often, the history will yield clues that may either direct further testing or eliminate the need for extensive testing. The physician’s role is to determine whether the child’s failure to thrive is primarily due to insufficient caloric intake, energy wasting, an increased caloric requirement, or altered growth potential. Dietary assessment should include a 24-hour dietary recall and/or completion of a 3-day food diary and observation of feeding when possible. Global assessment of parent-child interactions should also be undertaken. Clinical signs of protein-energy malnutrition may be present: loss of skin turgor, little subcutaneous fat, lack of activity (apathy), emaciation, sparse or lusterless hair, and poor nail growth. Additionally, there may be skin hypopigmentation or hyperpigmentation, rash, and edema. When needed, investigations should be selected on the basis of patient history and physical examination rather than ordered as a matter of routine. Laboratory tests not suggested by the patient history and physical examination are rarely helpful. A complete blood count, serum electrolytes, blood urea nitrogen, creatinine, albumin, calcium, phosphorus, alkaline phosphatase, urinalysis, and urine culture may assist in excluding systemic disease. Other more specific tests sometimes employed in the evaluation are shown in Table 30.4, and an algorithm is provided in Figure 30-1.

Table 30-2. Risk Factors for Failure to Thrive

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