Failure to Thrive: Current Clinical Concepts

After completing this article, readers should be able to: Failure to thrive (FTT) or growth failure has long been a major focus of attention and critical thought for pediatricians. Over many years, consensus has evolved about its cause, outcome, diagnosis, and management. By the last half of the 20th century, mainstream thinking held that FTT developed by one of two alternative mechanisms. On rare occasions, an underlying medical condition could lead to a failure of growth, which would present as “organic” FTT. In such cases, correct management of this underlying disorder would allow the patient to resume his or her normal growth. However, in most FTT cases, as many as 90% in some series, it was believed that no underlying medical diagnosis could be made. Affected children were said to have “nonorganic” FTT (NOFTT). This term and its synonym, “psychosocial” FTT, were often used as euphemisms to imply that the child was intrinsically normal and healthy and that the observed growth failure was due to environmental issues, most commonly family factors such as neglect, indifference, or other failures of parenting. This construct led to children receiving extensive medical evaluations to rule out diagnosable conditions and to prolonged hospitalizations that were designed primarily to document parenting difficulties and demonstrate vigorous and consistent weight gain under the care of hospital personnel. There was concern that, in addition to being at risk for acute complications of severe malnutrition from neglectful or disturbed parenting, children would inexorably suffer long-term adverse neurodevelopmental outcomes.This view of FTT is now outmoded. According to a large body of newer thinking, FTT is not a syndrome. It is, rather, a physical sign that a child is receiving inadequate nutrition for optimal growth and development. The work of the pediatrician is to determine, in an ordered and logical process, what may be leading to the inadequate nutrition and, when possible, to treat the underlying pathophysiologic issues, which often are multifactorial. Although this newer construct has now become the current mainstream view of clinicians and researchers working in the field of FTT, readers should be aware that the older, dichotomous view of “organic” versus “nonorganic” FTT may still color the thinking of some health professionals. Specifically, some medical licensure and certification examinations still may ask questions about FTT that reflect this dichotomous approach.Zenel in 1997 (1) and Gahagan in 2006 (2) wrote thoughtful reviews in this journal that lucidly outline the rationale for reconceptualizing FTT. Rather than repeating their extensive commentaries, this article seeks to complement their work by asking specific questions that highlight salient features of the new model and point out areas of concern or uncertainty that call for further research.Plotting a child's weight, length, and head circumference on standardized growth charts remains a critically important, essential step in providing an objective description of a child's growth and describing how far off the statistical norm he or she is. Frequently quoted chart-based definitions of FTT in children younger than 2 years of age include: a child whose weight is below the 3rd or 5th percentile for age on more than one consecutive occasion, a child whose weight drops down two major percentile lines, a child whose weight is less than 80% of the ideal weight for age, and a child who is below the 3rd or 5th percentile on the weight-for-length curve.As widely accepted as these definitions are, they are fraught with confusion. For example, the first two definitions require serial measurements over time. How is the clinician to respond when he or she notices a child who is “below the curves” on the first visit? The last two definitions facilitate diagnosis on one visit, but what about a child who does not meet the 80% criterion precisely or is not quite below the 3rd percentile but looks malnourished? These definitions do not provide standards for assessment of the body mass index (BMI) in children older than age 2 years. There is, in fact, some debate about the clinical utility of BMI measurement in very young children. How may the pediatrician most reliably identify FTT in an older child? Unfortunately, no standard uniform approach exists to identify reliably each child who has FTT solely by use of growth curves.There are other issues. First, the previously cited definitions do not clearly point out the need to evaluate whether a symmetric fall-off in the growth curves is present. They do not explicitly remind the clinician that when the FTT is due to poor food intake, weight tends to fall first, sparing the length and head circumference; that a symmetric fall in weight and height suggests a chronic medical condition; that short stature below the 50th percentile, with relative sparing of weight, suggests an underlying endocrine disorder; or that an early drop-off in head circumference suggests a lack of brain growth. The pediatrician still must exercise clinical judgment in interpreting seemingly objective data.Also, the widely accepted growth curve-based definitions refer to children who are believed to be generally healthy and free of underlying conditions that are known to affect growth. Children born with certain genetic conditions may appear to have FTT when they are evaluated using normal growth curves, but their perceived growth problems disappear when they are compared graphically to other children who have the same condition. Growth charts are readily available for such genetic conditions as Down, Turner, and Williams syndrome, among others, and it is essential to plot a child's growth on the appropriate curves to determine if FTT truly is present.Others who require special consideration include children who are chronically immobilized, such as those who have severe neuromotor disabilities. Often, such children have major oromotor dysfunction, are at risk for pulmonary aspiration syndrome, or have other issues that lead to inability to eat by mouth or maintain adequate growth. They often receive feeding gastrostomies to optimize nutrition. However, because they are immobile, they frequently have minimal caloric needs compared with other children and, thus, are at risk for excessive weight gain, even obesity. Such children may be difficult to weigh and measure correctly because of their neurologic status and immobility, making it difficult to assess their status using the standard growth curves. Other anthropometric techniques, such as measuring arm span or the ratio of upper body to lower extremity length, may be more appropriate.Another concern with the use of growth charts is that clinicians intuitively expect that a child is biologically destined to move along his or her predetermined growth channels inexorably and that any deviation from the original channel indicates a growth aberration. However, Mei and associates (3) described shifts in growth curves during the first 60 months of age in a cohort of 10,844 children. Between birth and 6 months of age, 39% of healthy children crossed two major percentile lines (up or down) on the weight-for-age curve, as did 6% to 15% of children between 6 and 24 months of age. Similar shifts occurred with the length-for-age curve. Strikingly, on the weight-for-height curve, 62% of children between birth and 6 months and 20% to 27% of children between 6 and 24 months crossed two major percentile lines. The authors concluded that pediatricians should consider the prevalence of growth rate shifts during infancy and early childhood before initiating evaluations of growth concerns.This caveat is humbling, for it is in precisely this age range that the question of FTT often is raised. Careful measurement of weight and length and thoughtful evaluation of the child's growth curves remain essential for diagnosis and management of growth concerns, but the pediatrician must still use clinical judgment and not be overly reliant on arbitrary mathematical definitions of FTT.For many years, there has been recognition that the undernutrition seen in FTT in first-world environments is typically not severe enough to lead to clinical conditions such as marasmus or kwashiorkor, although serious nutritional or vitamin deficiency diseases still may occur in very rare cases. However, a rich body of evidence, reviewed by Corbett and Drewett (4) in a 2004 meta-analysis, continues to suggest that poor nutrition in young children, especially infants, may result in long-term problems in cognitive development. On the other hand, Rudolf and Logan (5) reached opposite conclusions in another meta-analysis in 2005. They found that FTT was associated with an intelligence quotient (IQ) 3 points lower than expected, but the difference was of questionable clinical significance. They also reported that early-onset FTT was associated with some persistent reduction in weight and height later in childhood. However, they concluded that there was little evidence that FTT was predictive of damaging consequences for growth and intellectual development. In individual studies, a number of researchers have followed infants or toddlers who had FTT for periods as long as 8 years and reported measurable deficits in IQ, learning difficulties, and behavioral difficulties. (6)(7)(8) Some commentators argue that interpreting these findings is difficult because the study participants tended to have very severe FTT and significantly disordered family environments at the time of diagnosis, including problems such as overt parental mental illness and substance abuse.Although many children who experience FTT in early life eventually seem to have normal function, the overall trend is worrisome. A meaningful number of children have persistent intellectual or behavioral deficits, and it is currently impossible to predict which children will do well and which will have later difficulties. It is unclear whether energy or protein inadequacy alone is associated with the adverse long-term outcomes or whether deficiencies of vitamins, minerals, or other micronutrients might be responsible. For example, Lozoff and associates (9) showed that infants who experience iron deficiency anemia in infancy have measurably poorer developmental and behavioral outcomes 10 years later, despite having received appropriate treatment at the time of diagnosis.More recently, attention has started to turn to other, noncognitive developmental outcomes of early FTT. Drewett and colleagues (10) studied a group of 89 12-year-old children who had had FTT as infants. Compared with a control group, they were shorter, lighter, and had lower BMIs, and they reported having lesser appetites. They were satisfied with their body shapes and did not differ from the controls on measures related to anxiety, depression, or low self-esteem. The authors concluded that FTT in infancy is not associated with adverse emotional development in childhood. On the other hand, Raikkonen and coworkers (11) measured scores on a standardized assessment of adult hostility in a large cohort of adults who had a mean age of 63.4 years. The participants' growth histories were obtained by review of their birth, child welfare clinic, and school records. Men and women who had higher levels of hostility in adulthood were born lighter and thinner, showed slower weight gain from birth to 6 months, were lighter throughout childhood, and were heavier in adulthood than were individuals who had lower levels of hostility. There is no current consensus about long-term noncognitive, emotional sequelae of FTT in early childhood.Although methodologic difficulties continue to present problems in gathering data and analyzing long-term outcomes in children who have FTT, the general trend of the research is to express concern about long-term adverse effects on cognition, learning, and behavior. This line of evidence strongly supports the common current practice of instituting early and vigorous nutritional therapy for children who fail to thrive.Recognition that FTT is a physical sign of undernutrition allows a framework for classifying its causes. When considering the differential diagnosis, it is important to remember that FTT often is a multifactorial condition. Because a given patient may have more than one contributing factor to his or her poor growth, diagnostic evaluation should not automatically end as soon as one potential cause is identified. In addition to primary contributing factors, the pediatrician should pay heed to possible secondary exacerbating factors. Family stresses associated with the struggle to get an undernourished child to gain weight or stresses occurring after hearing that the physician is about FTT may another of factors that the FTT is a sign of the diagnostic approach must focus on that may occur because of one of mechanisms. The child may have inadequate intake, for growth. if in adequate he or she may have that from being available for growth. although a child may have appropriate of food and normal the he or she may have due to chronic or genetic or seen in the this allows the clinician to approach the diagnosis of a child and in and thoughtful consideration must be given to the clinical The assessment of whether adequate nutrition is being to the child to determine what of and are being the family what an appropriate is for their child's age and developmental there adequate for the family to these from the and the child's being correctly or is it the child an excessive of which may lead to adequate there evidence of the child have conditions that with food intake, such as oromotor dysfunction, developmental or feeding due to problems or in to there of conditions such as with or Often, an of nutritional the use of a food with by a to of vitamins, and also should the of with questions about and now require for and those should be although such does not have or A family of and should be children older than 6 months of age have been to that is a diagnostic should for a family of or endocrine conditions that may be associated with that In if the child is having the physician should ask about a family of protein or about a specific chronic that could are not during the clinical a review of should be to for of issues such as chronic or endocrine that may be associated with FTT. the physician should ask about the with attention to possible growth now strongly suggests that from any cause may be associated with which has long-term for growth potential and adverse sequelae if excessive weight gain is physical should focus on any clinical questions that have been during the It is appropriate to for of such as minimal in length that may be found in syndrome. growth measurements have not the head circumference and ratio or they should be readily measurement of and circumference provide about a child's nutritional to the view of FTT, in which it was essential to identify any “organic” extensive was to any and before making the diagnosis, by of “nonorganic” or “psychosocial” FTT, with its of parenting. However, as far as clearly showed that had very if clinical utility in the evaluation of FTT. In his review of children for FTT, he found that had causes. In the specific diagnosis was strongly by the and physical A of were for the group of were of diagnostic and of were in the whose diagnosis was strongly by and were by the of any of the there still is no evidence to the use of evaluations in FTT. of diagnostic to the construct in the should lead to a approach to However, this more approach has potential difficulties. Often, when the physician FTT and the family that their child is not the family to a They may at growth curves and even but they a child who to be and developmental the physician possible to adequate nutritional intake, he or she must a with the this may require the family that due attention is being given to the of the of some to the with the also allows the pediatrician to to the family that early of or behavioral of FTT is a of the overall evaluation of their child's clinical or mental health are of the diagnostic and are not an has been not to the physician that are even when there are no specific clinical a might include a with evaluate for anemia and iron a for and for and and a for for or growth deficiency should be if the child's length has and is below the 50th percentile on the length-for-age a length the 50th percentile is evidence that no endocrine disorder is and the multifactorial of FTT mean that a major of time and energy is for optimal evaluation and management. The of the pediatrician for a child who has FTT is by use of a In addition to the in medical diagnosis and there is a need for evaluation of the child's and oromotor nutritional needs and deficits, and family and The pediatrician is by working with other such as or physical and and the physician and use a some or of these in his or her medical it may be to the child in that However, if it is difficult or to provide this range of the and physician are by the patient to an of who have that of in FTT has In the dichotomous “organic” versus “nonorganic” FTT there were for was to the and of a of studies, including and and and to have the child seen by a range of to that was not being for was to present an appropriate and of food to the document that the child was that and consistent weight This approach was believed to the of the diagnosis of with its that parenting was the of and the child to health because poor nutrition was the It was that this could 2 or a of this approach is no or the recognition that children and their are by out of the if at possible, have to the use of hospital in children who have FTT. diagnostic and evaluations be on an The be that, in appropriate there is in having objective of a child's feeding he or she with Such serial evaluations may be in a hospital if are readily available and each feeding to evaluate the and the family to the child's food for FTT are not Children may be for to document weight gain with measured food intake, but even this practice is It is very difficult to evaluate weight over 2 or 3 or may be by or or by whether food or intake, or occur before or after the child is of weight gain growth measurements over which and should be in an current approach to FTT, to to nutritional by Such may include feeding or feeding if a of is There may be a for a to the family how to and a the general pediatrician or of in a care feeding in the because of on FTT is a sign of nutritional is the of in in which a is present or in which a chronic medical condition is medical or may by be to the child's nutritional status to or due to the condition or its treatment may a child's in or or feeding Family may respond to and by but their to the child during or feeding such cases, as well as in the more common in which the FTT is in large to poor of the first step in treatment is the of the child's or feeding and of how he or she with family during the child the child to at for a appropriate length of time and in a or at a the child have or food of certain or the child have or feeding such as or or or during the the child turn his or her head from or food in the mouth for long periods of on the of these it may be important to have a evaluation by an in oromotor in young children, such as an or and on the of such treatment may include such as oromotor food or in a to and working with the family to behavioral such as for and to of should be explicitly in the most in with have some behavioral reported in using designed to even with to nutritional intake, might or months to demonstrate appropriate weight gain and, in fact, may fail to the Because of the about potential long-term or behavioral sequelae of FTT, it may be to nutritional by years, many pediatricians for who have FTT have to early and vigorous use of feeding to weight gain and a to statistical on the growth curves. This often is but may still a number of months to the that there will be of the child does an in possible problems of the and and pulmonary aspiration of These issues for and for the for the a number of children receive a long-term feeding with or an of about feeding are and about their and is possible, to that have in this on the long-term growth of young children who have FTT are widely Some individuals appear to continue to be and throughout appear to be and some even appear to become is being given to the that certain individuals may be biologically to be at or that are below the standards that are generally accepted as on growth curves. In other what is normal may not be biologically According to this nutritional to weight gain may not be to has been as one cause for In and associates that children who might eventually as a to In and colleagues showed that young adults who had been born with in fact, demonstrate such evidence that a of term infants whose were the of may have who have are known to be at risk for FTT, and this group of infants may a According to this line of vigorous nutritional in such infants or young children who have FTT might their and eventually syndrome. Although an weight or BMI might be the normal that might be research has other evidence to this including of such as and There is no of such a child because body or measurements may not meet current standards for obesity. evidence the essential that some individuals may be to be and than typically is normal and that nutritional may outcomes.This line of thinking a major for the pediatrician for a child who has FTT. On the one hand, there is evidence, although not that some children who have FTT may have adverse neurodevelopmental evidence for nutritional However, some children who have to the are at risk of later in life if clinicians their growth For these children, nutritional therapy should be There is no for the physician at this each child must be evaluated