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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
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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. Other
definitions include weight 20% or more below ideal weight-for-height,
triceps skinfold thickness of 5 mm or less, or a depressed rate
of weight gain for age.
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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.
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