CHAPTER 146

Failure to Thrive

Carol D. Berkowitz, MD, FAAP

Failure to thrive (FTT) is a condition in which a child is not growing and developing at an appropriate rate for their age. The term is most often applied to infants and toddlers younger than 3 years. Failure to thrive is not a disease or even a diagnosis but represents a sign that a child’s size or rate of growth is below the expected. The term FTT first appeared in the pediatric literature in 1933 and was used for children whose growth impairment related to a suboptimal environment. Before 1933, the condition was referred to as “cease to thrive.” The terms “growth deficiency,” “growth impairment,” “undernutrition,” and “inadequate growth” are sometimes used interchangeably.

Historically, FTT has been divided into 2 distinct categories— organic and nonorganic. In organic FTT, an underlying medical problem, such as cystic fibrosis or congenital heart disease (CHD), is believed to contribute to the failure to grow at an appropriate rate. In nonorganic FTT, also referred to as environmental deprivation, inadequate growth is attributed to lack of nourishment and a non-nurturing home environment. Some physicians use the term FTT exclusively to mean environmentally related growth impairment. It is important to recognize that many children with growth problems have organic as well as environmental components, a condition sometimes referred to as multifactorial FTT or mixed FTT.

The diagnosis of FTT is entertained when the growth parameters of children as plotted on a standardized curve are below the fifth percentile in height and/or weight. Children who are above the fifth percentile may also be diagnosed with FTT if the rate of growth has decelerated and 2 major percentiles (eg, decreased from the 75th percentile down to the 10th percentile) have been crossed within 6 months (Box 146.1). Studies have shown, however, that between birth and 6 months of age, approximately 40% of healthy infants cross 2 major percentiles on the weight-for-age curve (up or down), as do up to 15% of children between 6 and 24 months of age. Similar trends are noted for length. The physician should, however, carefully track these infants to be certain that such changes are related to the child’s genetic disposition and not an environmental or medical problem.

The challenge for the physician caring for the child with FTT is to determine the etiology of the problem, which may not be readily apparent. Nonspecific, nondirected laboratory tests are not helpful because their yield is low and their cost is high. The evaluation of the small, underweight child requires a careful history and physical examination as well as an assessment of caregiver-infant interactions. A home visit helps because it permits evaluation of the caregiver-infant relationship in a more natural setting and an assessment of the family’s economic and food resources.

Epidemiology

The prevalence of FTT varies in different segments of the population. Poverty puts children at risk for undernutrition, and 12% of Medicaid recipients are below the third percentile in weight. Child neglect can result in FTT but is not a necessary component; 60% to 70% of cases of child abuse are reported for child neglect. Several other factors may contribute to variations in growth. All of these are not the result of a pathologic process but may reflect variations in individual genetic potential.

Environmentally related FTT may occur in different family settings. In some families, an acute depressive episode in the mother is the key component (see Chapter 24). Family living conditions are good, and the educational background of the mother is adequate. The depressive episode may be related to a loss that occurred during the pregnancy or shortly after delivery or to perinatal mood and anxiety disorders, a group of mental health conditions associated with pregnancy and delivery and manifested after birth. In these cases, the mother is too depressed, withdrawn, or preoccupied to interact effectively with her children. The condition may affect 25% to 30% of mothers, and the prevalence is influenced by many factors, including poverty, race, and access to health care. In other families, financial resources are marginal. The mother may be chronically depressed, and the father may be involved in alcohol or substance abuse. Domestic violence is a frequent occurrence (see Chapter 142). Spacing between children is fewer than 18 months, and the number of children is often the same as the age of the oldest child. The mother is too overwhelmed to meet the needs of all the children. A third type of family also involves a mother with depression and who has experienced losses, usually of a chronic nature. Her financial and educational backgrounds are adequate, but she views 1 of her children (the child who now presents with FTT) as bad or evil and the source of all her problems. As a result, an individual child is singled out, and the neglect is intentional.

Clinical Presentation

The child with FTT presents with low weight, short stature, poor appetite, or failure to gain weight or grow taller. Sometimes a parent or guardian may express concern; at other times, a teacher may detect a child’s growth problems. Some children with FTT are diagnosed during a health maintenance visit or during evaluation for another medical problem, such as a febrile illness. Following a child longitudinally will give the physician a better sense of the child’s growth pattern and a clue to the etiology of observed growth impairments. When nutrition is suboptimal, weight tends to decrease first, followed by length and, ultimately, head circumference.

Pathophysiology

The common pathway for the development of FTT, regardless of etiology, is insufficient calories to meet the nutritional needs of the child (Box 146.2). Caloric intake may be inadequate for several reasons. Some factors are societal, specifically poverty and inadequate access to food. Other factors may involve increased caloric needs. Certain chronic conditions are characterized by increased caloric expenditure (eg, some forms of chronic lung disease) or increased loss of ingested food (eg, diarrhea, malabsorption syndromes).

In environmentally related FTT, a disturbed caregiver-infant relationship contributes to reduced caloric intake and associated gastrointestinal symptoms (ie, vomiting). Although various disturbances in mother-FTT infant dyads have been described, maternal depression is the most common maternal feature noted in environmentally related FTT. Infants withdraw after unsuccessful attempts to interact with nonresponsive mothers, and infants become apathetic and dis-interested in food. Alternatively, overactive mothers, some of whom have an untreated bipolar (eg, manic-depressive) disorder, are out of synchrony with their infants. The infants become agitated, especially during feedings, and cannot feed and frequently vomit. These infants, who may interact with persons other than their mothers, usually do well in other environments or when their mothers receive appropriate therapy.

Older children with long-standing environmental deprivation have disturbed hypothalamic-pituitary functioning. The etiology of this dysfunction is uncertain but has been attributed to sleep disturbances with an effect on levels of growth hormone.

Some children develop FTT as a result of a feeding disorder. The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) includes a new diagnostic category, avoidant/restrictive food intake disorder (ARFID), which includes individuals of all ages with reduced food intake without necessarily having body image concerns. The DSM-5 describes 3 examples of ARFID: sensory sensitivity (includes children with texture aversions); low appetite or lack of interest in food (ie, picky eater); and avoidance of specific foods because of a prior traumatic experience (eg, choked while eating meat.)

Differential Diagnosis

The growth of the child with FTT may be impaired in weight, height, head circumference, or any combination of growth parameters. If weight is the only abnormal parameter, inadequate caloric intake, excess caloric loss, or increased caloric expenditure is likely the major problem. If height is reduced and weight is appropriate or high for height, the diagnosis may be short stature rather than FTT. Small head circumference in the setting of low growth parameters is suggestive of a central nervous system basis for the growth delay. It is important to determine if the child’s skills are developmentally appropriate when determining the etiology of FTT. Affect and interactional skills should be noted as well. Environmentally deprived infants are apathetic and noninteractive. They appear hypertonic and may be diagnosed with cerebral palsy or have features suggestive of infantile autism spectrum disorder; however, their symptoms resolve with a change in surroundings.

The most common causes of short stature include familial short stature and constitutional delay. The child with familial short stature is small because the parents are short. The bone age of the child with familial short stature is the same as the child’s chronologic age. Except for a deceleration in growth, which usually occurs between ages 6 and 18 months, the child with constitutional delay appears healthy. Unlike the child with familial short stature, the child with constitutional delay has a delayed bone age that is comparable to the child’s height age (ie, the age when height is at the 50th percentile), however. In the child with familial short stature or constitutional delay, growth parameters at birth are usually normal.

The child with low growth parameters at birth may have been born preterm or have experienced intrauterine growth restriction (IUGR). Most studies support the notion that well preterm infants exhibit catch-up growth (head circumference by 18 months, weight by 24 months, and height by 40 months). The ill preterm infant may not demonstrate such catch-up growth because of increased caloric needs related to residual medical problems (eg, chronic lung disease) or impaired nutritional intake resulting from certain conditions (eg, cerebral palsy with discoordinated swallowing). Overall, 15% of infants who are classified as IUGR or small for gestational age do not exhibit catch-up growth. Significant evidence now exists that IUGR may be associated with insulin resistance and subsequent propensity to obesity and metabolic syndrome. Disturbances in leptin, ghrelin, and adiponectin have also been described. This has significant implications for the management of these infants vis-à-vis their nutritional intake. It is postulated that some individuals are “programmed” to be slighter and smaller, and nutritional interventions to achieve a more average weight have deleterious effects later in life.

The child who is small for gestational age may have experienced any of several in utero insults that affect postnatal growth, including exposure to cigarettes, alcohol, and illicit drugs. Additionally, maternal infection with such diseases as rubella may result in a congenital infection in the infant with subsequent growth impairment.

Several other conditions may result in disturbed growth, including endocrine disorders, skeletal dysplasia, food allergies, and malabsorption. These conditions occur less frequently and are usually more readily apparent as children undergo evaluation for the growth problem.

Evaluation

History

Careful questioning about certain specific topics provides clues to diagnosis in approximately 95% of cases. The physician should learn about the pregnancy and delivery, the family history (including parental heights), the child’s medical and dietary history, and the child’s feeding pattern.

It is important to obtain an in-depth history of the pregnancy and delivery (Box 146.3). The infant’s birth weight and gestational age are key pieces of information. Low birth weight is said to account for 20% to 40% of short stature in children from low-income families. It is helpful to confirm that neonatal screening for genetic and metabolic diseases was normal. Recurrent spontaneous abortions suggest that a mother may have an underlying problem, such as a balanced chromosomal translocation that results in fetal wastage. The mother who has experienced repeated losses may have difficulty bonding with subsequent babies. The physician should determine whether the mother used cigarettes, alcohol, or drugs during the pregnancy by asking the mother questions beginning with the phrase, “How much?” Any medications taken by the mother may affect the subsequent growth of the infant.

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