Continuing Education Activity

Failure to thrive (FTT) or weight faltering is commonly used to describe a lack of adequate weight gain in pediatric patients. Accepted definitions include a weight for age less than the fifth percentile on standardized growth charts, a decrease in weight percentile of more than 2 major percentile lines on the growth chart, or less than the 80th percent of median weight for height/length ratio. Given the many causes of FTT, clinicians must obtain a thorough history and physical exam. Healthcare professionals should recognize that inpatient management has a role if the patient is more severely malnourished, has other underlying conditions, or has failed outpatient management. FTT is essential to recognize and treat because it can result in developmental delays and other long-term effects for the developing child. As the underlying reason for FTT is often related to inorganic etiologies of inadequate caloric intake, leveraging an interprofessional team, including nutrition, behavioral health, and social workers, can be especially helpful when caring for pediatric patients with FTT. This activity reviews the evaluation and management of FTT and highlights the role of the interprofessional team in the care of patients with this disorder.

Objectives:

• Identify the common signs and etiologies of failure to thrive and weight faltering in pediatric patients.

• Assess the physical, nutritional, and psychosocial factors contributing to failure to thrive and weight faltering in pediatric patients.

• Implement evidence-based growth monitoring and nutritional interventions for children at risk of or experiencing failure to thrive and weight faltering.

• Collaborate with an interprofessional team, including dietitians, social workers, and specialists, to develop comprehensive care plans for children with failure to thrive and weight faltering.

Introduction

Failure to thrive (FTT) is a common term to describe a lack of adequate weight gain in pediatric-aged patients. Despite its common use as a descriptive diagnosis, the exact definition of the condition remains debated. Therefore, measuring patient outcomes and complications specifically associated with the finding of FTT can be challenging.[1] Various anthropometric criteria for the diagnosis have been proposed. Current consensus defines FTT as a weight for age less than the fifth percentile on standardized age-based growth charts, a decrease in weight percentile of more than 2 major percentile lines on the growth chart, or less than the 80th percent of median weight for height/length ratio.[2] Growth percentiles should be adjusted for infants born prematurely to reflect corrected gestational age through the first 2 years of life. In general, a decline in weight percentile is more concerning than a patient who has always trended in a lower percentile range and may be meeting their expected growth potential. As the unifying concern relates to inadequate nutrient intake to meet the body's demands resulting in poor weight gain over time, the renaming of the condition as "weight faltering" has been proposed.[3] Weight faltering offers a clearer description of the objective criteria utilized by clinicians to make the diagnosis and removes the term "failure," which has been interpreted by many patient families as overly critical.[4][5]

The diagnosis of FTT/weight faltering hinges on routine weight and length/height measurements trended over time by the astute clinician for pediatric patients of all ages. In addition to the accepted percentile-based definitions, z-score is a helpful additional assessment of how far a child's weight for length/height deviates from the expected mean. Expressed in standard deviation (SD), a z-score of -1 represents a weight for length/height 1 SD below the mean. Utilizing z-scores rather than absolute percentiles can paint a more accurate picture of the patient's growth status relative to expected norms. This calculation also offers a more precise way to trend weights over time, especially for those children whose anthropometric percentiles fall well below the established curve.[6] 

FTT/weight faltering is a significant risk factor for malnutrition. Furthermore, the lower the z-score (suggesting a larger negative deviation from the mean), the higher the risk for severe malnutrition.[6] Therefore, recognizing and evaluating the findings of FTT by optimizing nutrition and treating any underlying medical etiologies are essential. Left untreated, FTT can lead to stunted growth and has been associated with developmental delays and other significant long-term effects in the developing child.[5] Increasingly, it has been recognized that not all calories are created equal. The true goal is ensuring that the developing pediatric patient consumes needed macronutrients, vitamins, and minerals to support healthy brain development in addition to baseline weight gain.[7] Multiple studies have demonstrated that the effects of poor nutrition on cognitive development are more profound in younger patients, especially those younger than the age of 2 years and those with more prolonged malnutrition. In these studies, FTT was associated with decreased IQ, increased neurocognitive or behavioral challenges such as Attention-Deficit Hyperactivity Disorder (ADHD), learning disabilities, and impaired communication skills.[6][7][8][9]

Etiology

FTT/weight faltering represents a red flag that warrants further evaluation to determine the underlying etiology of the patient's poor weight gain. As the broad definition of FTT suggests, any underlying condition that leads to an imbalance of available calories or nutrients and the body's caloric demand will result in poor weight gain if not addressed. Therefore, it is helpful to break down the potential etiologies into a few broad categories to help guide evaluation and treatment strategies.[4][10]

The first helpful breakdown is to consider if the etiology is related to an underlying organic medical condition, decreased caloric intake from an inorganic cause, or both.[5] Inadequate caloric intake to support weight gain from inorganic causes is the most common etiology of FTT and is often multifactorial.[10] Examples might include improper mixing of infant formulas, inadequate breast milk supply or difficulty with milk transfer at the breast, lack of parental knowledge of appropriate feeding volumes, patient feeding refusal or other maladaptive feeding behaviors, food insecurity, and less commonly parental abuse or neglect. A thorough patient history, including a detailed feeding history as well as a psychosocial and behavioral history, can be invaluable in teasing out risk factors for inorganic etiologies of poor caloric intake and guiding treatment interventions. While inorganic etiologies are the most common for FTT, it is essential to recognize that many environmental and socioeconomic factors may be outside the family's control. An important role of the clinician is identifying these concerns and connecting families with additional community resources when needed.[11] While it is helpful to first think of organic and inorganic etiologies separately, the underlying cause of FTT is often multifactorial. Therefore, it is not unusual for an organic medical condition to be exacerbated by 1 or more inorganic factors.[12]

After considering organic versus inorganic etiologies and how they might overlap, the second helpful framework is to think about 3 big categories of why a patient may be unable to meet their body's caloric needs.[4][5] The 3 categories are inadequate caloric intake, increased caloric losses/malabsorption, and increased systemic caloric demand. Considerations in each category include the following:

Inadequate Caloric Intake

Underlying conditions in this category can result from organic or inorganic etiologies. Organic etiologies include oral-motor dysfunction or craniofacial abnormalities that prevent the patient from consuming enough calories by mouth. Patients with esophageal abnormalities, gastroesophageal reflux, or pyloric stenosis can all experience difficulties maintaining adequate caloric intake due to calorie loss through emesis or anatomic structure abnormalities preventing adequate oral intake. As mentioned above, many inorganic contributing factors to inadequate caloric intake may exist in isolation or exacerbate underlying organic etiologies.

Increased Caloric Losses/Malabsorption

Underlying conditions in this category tend to be organic etiologies and typically are gastrointestinal conditions that result in malabsorption. Examples include inflammatory bowel disease, celiac disease, milk-protein allergy, exocrine pancreatic insufficiency such as cystic fibrosis, and other protein-losing enteropathies. These conditions can also all be exacerbated by inorganic factors.

Increased Systemic Caloric Demand

Underlying conditions in this category tend to be organic etiologies resulting from chronic diseases such as congenital heart disease, kidney or liver disease, anemia, malignancy, and chronic infectious diseases. In these conditions, the patient's caloric demand is much higher than average, making it challenging to consume enough calories to meet this demand. Inorganic factors can exacerbate these conditions, highlighting the importance of a comprehensive diet and psychosocial history for any patient presenting with FTT.

Epidemiology

FTT/weight faltering can affect children of all ages, genders, and ethnicities. However, it is more commonly diagnosed in children younger than 2 years. FTT is also more concerning for children diagnosed at younger ages because of the association with long-term adverse neurodevelopmental outcomes. Given the ongoing variance in diagnostic criteria, FTT incidence estimates range from 5% to 10% of pediatric patients evaluated in the outpatient clinic setting in well-resourced countries.[4][13][14] In lower-resourced environments, the incidence of FTT may be much higher, with some estimates ranging from 20% to 30% of pediatric patients.[2][14]

Up to 86% of FTT cases are attributed to inadequate caloric intake, most of which are related to inorganic causes.[4] The remaining cases are attributed to underlying organic medical conditions with acute illness, gastrointestinal, endocrine, genetic, and other systemic inflammatory disorders as common etiologies.[10] Multiple studies have reported that patients diagnosed with FTT at younger ages (younger than 6 months of age particularly), patients with a history of prematurity, and patients with a more severe decline in weight/height z-score (z-score of <-3) were statistically more likely to have an underlying organic medical condition and more likely to require hospitalization for evaluation and initial treatment.[15][16][17]

While FTT can affect any child, certain patients are at higher risk. Patients with a history of prematurity, low birth weight, developmental delays, congenital anomalies, or known chronic/systemic illness are more likely to be diagnosed with FTT. FTT has been associated with lower socioeconomic status, lower parental education level, increased psychosocial stressors in the home environment, parental behavioral health conditions, and parental substance abuse.[4] Patient feeding behaviors, family feeding routines and perceptions of nutrition, and food allergies or other restrictive eating patterns are also increasingly important risk factors.[15][18]

Pathophysiology

The foundational pathophysiology of FTT/weight faltering is inadequate caloric intake to maintain the body's nutritional demand to sustain growth. While overall calories are essential for weight gain, the macronutrient, vitamin, and mineral content of calories consumed is also important when assessing a child with FTT. The specific pathophysiology contributing to the caloric deficit varies with each potential underlying condition. Therefore, FTT should be considered a condition that warrants further evaluation to determine the underlying etiology causing the inadequate weight gain and assess for potential risk of malnutrition.[6]

Most FTT cases are attributed to inadequate caloric intake. In these cases, it is helpful to support the patient by estimating daily energy requirements based on age, gender, activity levels, and energy requirements required for catch-up growth. Other patients with FTT may have an underlying medical condition that causes malabsorption, leading to a relative caloric deficit based on the body's energy requirements. Lastly, patients with chronic/systemic medical conditions may have increased metabolic demand, requiring more calories than expected to maintain their growth.[10]

History and Physical

While some patients may have a known medical condition and present with signs and symptoms of the underlying illness and poor weight gain, it is much more likely that FTT/weight faltering is noted at a routine well visit without other apparent signs/symptoms. Therefore, reviewing the growth charts at every pediatric visit is essential. Once it is determined that the patient meets the FTT criteria, there are many critical aspects of the history and physical examination to consider.

Feeding History

Obtain a detailed feeding history, including types of food, amounts, and frequency in which foods are consumed. For infants, determine if the baby is feeding overnight or only during the daytime. If the infant is breastfed, determine the duration of feeds, maternal estimates of milk supply and infant's ability to transfer milk at the breast, breast pumping history, and volumes of expressed breast milk if applicable. If the infant is formula-fed, identify the type of formula and mixing technique the family uses. For bottle-fed infants, consider asking about the type of bottle and nipple flow rate. If possible, observing a feed can be particularly useful to assess infant feeding tolerance and any associated symptoms during feeding, such as choking/gagging, stridor, or other signs of distress. In older infants and children, determine if parents have noticed any feeding refusal and in what circumstances, texture preferences, difficulty swallowing, gagging, abdominal pain, or any nausea/emesis associated with feeds. Families may follow restrictive diets for various reasons, such as food allergies, religious or philosophical preferences, or inadequate economic resources to obtain a wide food variety. If possible, it can also be helpful to elicit parental views/perspectives on meal times, diet/nutrition choices, and any other psychosocial stressors that might be contributing.[15][19] Approaching the patient's history with cultural sensitivity is key to establishing a partnership with the family and understanding potentially diverse feeding practices and cultural perceptions about weight gain and dietary norms that may affect the patient's growth.[5]

Elimination History

Stool frequency and consistency should be elicited, as well as any dietary factors associated with changes in stool pattern. Red flags include blood or mucus in the stool, large bulky/foul-smelling stools, and, in older children, waking at night with stool urgency or new episodes of stool incontinence when previously potty trained. Urine output as an overall marker of hydration and any unusual smells or symptoms of infection, such as frequency, urgency, or dysuria, should be documented.

Birth, Past Medical, and Developmental History

Any history of prematurity, birth complications such as small for gestational age, neonatal hypoglycemia, or jaundice should be noted. Maternal prenatal history focusing on any known toxin/drug or infectious exposures should also be considered. Developmental milestones should be assessed, and any delays documented. Confirm that the patient had a normal newborn metabolic screen per state or country recommendations. The past medical history may provide clues to an underlying organic etiology. Specifically, congenital abnormalities such as known congenital heart disease, chronic lung disease, esophageal abnormalities, intestinal abnormalities, endocrine disorders, and genetic disorders are often associated with FTT. A history of atopy can be a clue to other underlying food allergies or eosinophilic esophagitis. In addition, a prior history of poor weight gain and any previous interventions can be important factors to consider.[5] 

Review of Systems

A comprehensive review of systems is helpful to screen for any indications of an underlying illness that could contribute to poor weight gain. Tachypnea, fatigue, or diaphoresis with feeds may indicate an underlying cardiac condition. Skin rashes can be associated with various systemic illnesses and some vitamin deficiencies. Additionally, joint aches or swelling, peripheral edema, and muscle weakness or hypotonia can all be associated with underlying systemic conditions.[14]

Family Medical and Social History

Determining known medical conditions in the family, including a history of siblings with chronic medical conditions or a history of FTT, should be documented. Parental food allergies or preferences can contribute to restrictive household diets and should be noted. A thorough social history should be elicited, including family dynamics and social support network, any history of food insecurity, parental health/nutrition literacy, and potential environmental exposures such as medications in the home. In some cases, a family history of travel or country of origin can be helpful to identify less common risk factors for poor weight gain.[11]

Physical Examination

Note the rate of weight gain or loss from the last visit as well as the current weight and length/height percentiles and z-scores. A head-to-toe physical exam carefully assessing for any abnormalities can offer hints to an underlying organic etiology for the patient's poor weight gain. Specific findings that should be noted are any dysmorphic features, oral motor dysfunction, thyroid nodules or goiter, presence of a heart murmur, tachypnea, focal lung abnormalities, abdominal pain or abdominal masses, organomegaly, genitourinary abnormalities, including anal fissures or mucosal abnormalities, joint swelling or erythema, peripheral edema, neurologic abnormalities such as hypotonia, skin rashes or nail abnormalities, pallor, bruises or skin abrasions. Assessing the patient's general affect may also be helpful, noting fussiness or irritability and interpersonal interactions with parents or other family members in the exam room. The physical exam will often be notable only for poor weight gain and a thin-appearing patient without providing any specific clues to the underlying cause.[14]

Evaluation

Evaluation of FTT/weight faltering should start with analyzing the patient's available anthropometric measurements. The patient's weight trend over time should be determined and compared against expected norms for age. In general, thriving children do not lose weight. Therefore, weight loss from a previous visit is a red flag that warrants further investigation. Considering differences in scale calibration, articles of clothing worn at the time of previous measurement and recent acute illness can all contribute to weight variance not associated with chronic FTT. Assessment of the patient's weight for length/height z-score is also helpful to gauge the risk and potential severity of malnutrition and to trend over time. Currently accepted z-score ranges are mild malnutrition (z-score -1 to -1.9), moderate malnutrition (z-score -2 to -2.9), and severe malnutrition (z-score <-3) and can be further characterized as acute changes (<3 months) or chronic (>3 months) in duration.[6][20] To guide clinicians, the Semi-Objective Failure to Thrive (SOFTT) tool may be a helpful adjunct to clinical assessment. This validated tool utilizes scoring criteria to grade factors from the patient's growth trajectory, history, review of systems, duration of poor growth, and mid-parental height to assess the diagnosis and severity of FTT versus a patient whose weight may chart at a lower weight percentile but not truly be concerning for FTT.[21]

Depending on the severity of weight loss or decline in weight trajectory at initial presentation and the patient's clinical status, it is reasonable to evaluate only with a thorough history and physical exam.[5] History should include an in-depth feeding and psychosocial history and elicit any red flags for potential organic etiologies of the patient's poor weight gain. If possible, observing young infants feed can be particularly informative. In the absence of red flag findings, partnering with the family to establish nutritional intake goals to meet expected caloric demands, scheduling close follow-up for a repeat weight assessment, and limiting any initial laboratory evaluation are encouraged.[22][23] Utilizing a stepwise flow chart to guide the assessment of the patient's clinical features and the next steps in evaluation/intervention can minimize unnecessary testing.[17]

In patients who are ill-appearing, have severe weight loss or other red flags suggesting underlying organic medical conditions, have not gained weight with initial dietary interventions, or in patients where follow-up cannot be ensured, an initial laboratory evaluation is warranted.[17] If not done previously, observing a feed and formula preparation, if applicable, is a helpful assessment in younger infants. Laboratory evaluation should screen for the most likely organic causes based on the patient's history and physical examination. Results may guide the clinician to more specific tests if needed. Initial labs include a complete blood count (CBC) to assess for anemia, an iron panel because the most common type of anemia in this age group is iron deficiency, and a metabolic panel to assess electrolyte and hydration status and liver and kidney function. If there is a concern for severe malnutrition and risk of refeeding syndrome, the metabolic panel should include a baseline phosphorus and magnesium level in addition to the standard electrolytes included on the basic metabolic panel.[24] An erythrocyte sedimentation rate (ESR) can be useful to identify nonspecific underlying inflammation.[5] Assessing thyroid function with thyroid-stimulating hormone (TSH) and free T4 should be considered. Ensure a normal newborn metabolic screen is documented; if not, sending one can provide clues to less common organic causes of FTT, such as inborn errors of metabolism. A urinalysis and urine culture help assess for kidney diseases and screen for a common chronic infection. If there is a prominent history of abnormal stool patterns or blood/mucus in the stool, obtain stool studies including culture, guaiac, fecal calprotectin, and reducing substances. A celiac panel including tissue transglutaminase immunoglobulin A (IgA) and total IgA may also be helpful if the patient is experiencing gastrointestinal symptoms.[5] Low prealbumin can be a marker of more severe malnutrition, although consensus on its clinical utility remains lacking.[25] Pending results of the first set of basic labs, more specific labs may be indicated, such as a chloride sweat test, pancreatic function testing, or other metabolic-specific testing such as an ammonia level. While imaging is not routinely indicated initially, a chest radiograph, ECG, abdominal radiograph, and an upper GI series may be useful if the patient has a positive review of systems. In consultation with pediatric subspecialists, endoscopy or echocardiography may be warranted if other findings are concerning for underlying disease within these body systems.[4]

While evaluating the potential underlying etiologies contributing to a patient with FTT, it is important to recognize the multifactorial aspect of this condition and the potential for overlap between inorganic and organic etiologies. Historically, inorganic etiologies are not uncommonly thought to result from parental neglect or even abuse.[26] More recent studies have found that neglect/abuse is much less likely, and inorganic etiologies of FTT are more often related to lack of parent education, poor feeding skills or other maladaptive child feeding behaviors, and lack of parental resources to support adequate nutrition.[18] Given parental neglect and abuse do happen, the clinician must consider this possibility, evaluate further if red flags are identified, and involve social work services early. Neglect should be considered in cases where the recommended treatment is known to benefit the patient, outweighs the known risks of treatment, and the caregiver understands and has access to the recommendation but decides not to act. Patients with special needs and developmental delays may be at increased risk for nutritional neglect.[27] Medical child abuse can include intentional food withholding/starvation or cases of factitious disorder by proxy. Red flags can include treatment refractory FTT, more than 5 organ system complaints, more than 5 reported allergies, lack of an identified medical diagnosis after extensive evaluation, and parental refusal to participate in multidisciplinary clinic evaluations.[28]

Treatment / Management

The fundamental treatment strategy for FTT/weight faltering involves implementing feeding strategies to optimize the patient's caloric intake and determining the most likely underlying etiology of the patient's poor weight gain. The clinician should start by obtaining a thorough history and physical examination with judicious use of laboratory and radiology tests and subspecialty consultation if needed. Once underlying etiologies are identified, treatment efforts should be tailored to therapies specific to those etiologies if possible. Lastly, close follow-up is essential to trend the patient's response to interventions and weight gain over time.[14][23]

Optimizing the patient's nutrition and overall feeding routine is the first step, regardless of the underlying etiology. This can often be managed in the outpatient setting with the help of an interprofessional team. Calculating the patient's daily energy requirements, caloric requirements needed for catch-up growth, and any nutritional supplements required to mitigate identified micronutrient deficiencies is helpful.[4] A nutritionist can be an invaluable resource in helping to outline an appropriate feeding plan to optimize nutrition. Specific nutritional strategies must be individualized and vary depending on the patient's age and any other underlying organic medical conditions identified. As most patients with FTT have inorganic etiologies contributing to their inadequate caloric intake, offering strategies to increase overall calories and optimize the home feeding routine are critical aspects of any treatment plan. For breast or formula-feeding patients, the frequency and volume of feeds can potentially be increased. Adequate maternal milk supply should be confirmed, and if inadequate, lactation support should be provided. Proper mixing of infant formula per package instructions should be confirmed. If a patient cannot tolerate increased volume or frequency of feeds due to an underlying medical condition or feeding refusal, the caloric density of the feed can be increased.[5] Multiple recipes exist to guide the preparation of formula or supplement breast milk to achieve higher caloric ratios per ounce. In general, most infants can tolerate increasing the caloric density to 22 to 24 kcal/ounce instead of the standard 20  kcal/ounce breastmilk caloric density. In some cases, fortification to 27 kcal/ounce can be offered, but some infants may develop increased gastrointestinal side effects such as constipation at this concentration. Suppose the patient is old enough for solid foods. In that case, caloric density can be increased by offering high-fat/high-calorie options such as heavy whipping cream, avocado, and peanut butter and supplementing other foods with oils and butter.[10] In general, supplementing nutrition with whole foods is desirable instead of utilizing commercially available nutrition shakes or other products. There can be a role for these products; however, consulting with nutrition is particularly helpful to identify the best supplement to fit the patient's needs if unable to maintain adequate growth with whole foods alone. With any recommended diet modifications, being mindful of any underlying food allergies or dietary/cultural preferences and offering nutrient-dense alternatives will increase parental buy-in and compliance with the proposed treatment plan.[5]

Optimizing the home feeding routine is likely the most impactful intervention in addition to increasing overall caloric intake. Specific strategies may vary based on challenges faced by individual families, but general recommendations might include establishing a feeding routine, including specific meal and snack times and limiting grazing. Minimizing fruit juices and other empty calories is also helpful. Sitting down as a family to eat and role-modeling appropriate feeding behavior can be helpful if feasible for the family. Patients should be offered foods in developmentally appropriate locations, with mealtimes limited to 20 to 30 minutes.[10] Coaching families to reduce stress regarding meal times and avoid force-feeding or shaming for feeding behaviors has been demonstrated to facilitate a healthier relationship with food and support patient growth and development.[13] Parental education about healthy diet choices and potential nutritional deficits if following alternative diets should be offered. Consideration of limited parental resources, such as food insecurity or other barriers to following through with the proposed treatment plan, should be assessed and discussed if applicable.[5][11]

In addition to optimizing nutritional support for patients with an underlying organic etiology contributing to their poor weight gain, specific therapies should address the underlying condition. These therapies will vary with the underlying condition but could include medication initiation, dietary avoidance of identified allergens, surgical repair of anatomic abnormalities such as pyloric stenosis, cleft lip/palate, or congenital heart disease, and initiation of behavioral/developmental therapies. For chronic medical conditions with increased caloric demand or underlying genetic conditions, there may be no specific intervention for the condition itself. The most critical intervention for these patients will be to optimize nutrition to compensate for the increased caloric demand and monitor growth over time, often in conjunction with an interprofessional team.[12]

In general, most patients with FTT can be managed as outpatients as long as the patient is not acutely ill or severely malnourished. Indications for hospitalization include the need to more accurately assess details of nutritional intake, severe malnutrition or dehydration, suspicion of a severe underlying medical condition, need to expedite evaluation, suspicion of child abuse/neglect or significant parental impairment, or failed outpatient management.[17] Hospitalization does provide a controlled environment to optimize nutritional intake, directly observe patient behaviors related to feeding and parental feeding strategies, and trend weight gain more precisely. Even for patients requiring hospitalization, most still have an inorganic etiology for their FTT. Therefore, optimizing caloric intake and monitoring for weight gain should be the first inpatient intervention.[29] Patients with severe malnutrition (weight/length z-score <-3), significant weight loss, greater duration of inadequate caloric intake, known chronic medical conditions, and any baseline electrolyte abnormalities are at increased risk for refeeding syndrome. Feeds should be slowly advanced for these patients with close monitoring for abnormalities in serum potassium, magnesium, and phosphorus levels and the patient's overall clinical status.[24] If the patient cannot demonstrate weight gain with increased caloric intake, further diagnostic testing and subspecialty consultation can be expedited while inpatient. Pending evaluation results, the patient may need other interventions to treat an underlying condition or more invasive strategies for nutritional support. These strategies may include a nasogastric tube or gastrostomy tube placement for enteric feeds or, rarely, total parenteral nutrition (TPN).[17][29]

Differential Diagnosis

The differential for the underlying etiology of an infant or child's FTT/weight faltering is vast and, in many cases, can be multifactorial. As noted above, FTT traditionally refers to inadequate weight gain or weight loss as the primary condition. Patients with severe malnutrition can experience declines in their linear growth (height) trajectory or head circumference. Therefore, an important differential diagnosis for FTT is primary short stature unrelated to malnutrition. Short stature is diagnosed when a patient's length/height z-score is ≤-2 (2 SD below the mean for age/gender). If identified, assessing the patient's other anthropometric values and ideally analyzing the growth trends over time helps differentiate FTT from short stature.[30] Short stature is a diagnosis with a wide differential, including growth hormone deficiency, constitutional delay of growth, familial short stature, and idiopathic short stature.[31] In addition to a thorough history and physical examination, calculating the patient's mid-parental height and trending linear growth velocity helps differentiate these etiologies. Other diagnostics might include obtaining a bone age radiograph, growth hormone level, and insulin growth factor (IGF-1).[30]  Endocrinopathies associated with poor linear growth include Cushing Syndrome, thyroid dysfunction, and hypopituitarism. Many genetic syndromes can be associated with poor linear growth and FTT, and these conditions should also be differentiated as these complex patients may require different treatments, and long-term prognosis is often not as favorable.[12][30] Lastly, iatrogenic causes of short stature, such as prolonged systemic corticosteroid exposure, should be considered (see Table 1. Common Differential Diagnoses for Short Stature).[12][30]

Table 1. Common Differential Diagnoses for Short Stature in the Absence of Poor Weight Gain/Malnutrition

If the patient's history, physical examination, and growth parameters do not indicate any of the above conditions, it is important to consider both organic and inorganic etiologies of the patient's FTT. A helpful way to break down the differential for FTT is to consider if the inadequate weight gain results from inadequate caloric intake, excessive loss/malabsorption, or increased systemic caloric requirements. Sixty to eighty percent of patients with FTT have at least some inorganic component as an underlying etiology. While the frequency of primary organic diagnoses varies, gastrointestinal, endocrine, and cardiac causes are the most common (see Table 2. Common Differential Diagnoses for FTT/Weight Faltering).[5][16][32] 

Table 2. Common Differential Diagnoses for FTT/Weight Faltering

Prognosis

The prognosis of FTT/weight faltering depends on the underlying etiology that led to inadequate caloric intake. In general, once poor growth is recognized and steps are taken to improve the patient's caloric intake, the patient will demonstrate weight gain. The earlier this intervention is implemented, the better to support long-term growth and developmental outcomes.[33] In patients with inorganic FTT who can modify their diets to increase caloric density and improve feeding behaviors based on guidance from the medical team, nearly all patients are able to maintain a healthy growth trajectory.[22] Prognosis varies, however, if dietary recommendations cannot be implemented due to lack of understanding, lack of parental resources to implement those changes, underlying feeding or other organic conditions that were not previously discovered, or parental noncompliance.[16]

In patients with organic medical conditions that led to FTT/weight faltering, the prognosis may be more varied and tends to be more closely mirrored to the prognosis of the underlying condition. Specific treatments must address the underlying condition and where effective therapies exist for that condition; patients tend to respond favorably. In conjunction with treating the underlying condition, adequate nutritional support is essential. With this support, most patients can maintain a healthy growth trajectory within the limitations of their underlying condition.[16]

Complications

FTT/weight faltering's most notable near-term complication is worsening malnutrition. This can lead to multiple complications, including loss of lean body mass, muscle weakness, electrolyte abnormalities, micronutrient deficiencies, immune dysfunction, subsequent infections, delayed wound healing, and prolonged hospitalizations.[6] For patients with moderate to severe malnutrition, refeeding syndrome can be a complication upon reintroduction of adequate caloric intake. It must be mitigated by identification of patients at the highest risk, slow reintroduction of feeds and fluid rehydration, and close monitoring for electrolyte abnormalities.[24]

Most patients who require hospitalization for treatment and/or evaluation of FTT respond well and transition to outpatient management. The need for readmission is a potential complication, and one study reported 14% of patients required readmission. Readmission was more likely in patients with at least 1 underlying complex chronic disease, a history of prematurity, and/or patients from families with lower socioeconomic status.[34]

For patients who cannot consume enough calories by mouth to meet their body's nutritional demand, enteric feeding via nasogastric or gastrostomy tubes may be needed. Depending on the underlying etiology of the patient's FTT, these measures may be temporary until the patient can increase their caloric intake by mouth. Lifelong gastrostomy tube feeds may be needed to support nutrition for patients who cannot feasibly return to oral feeds due to underlying medical conditions.[35]

If unaddressed, FTT can lead to significant long-term neurodevelopmental complications, including reduced IQ, increased neurocognitive or behavioral challenges such as Attention-deficit hyperactivity disorder (ADHD), learning disabilities, and impaired communication skills. Patients younger than 2 years of age, especially younger than 2 months, are at the highest risk for poor neurodevelopmental outcomes.[6][7][8][9]

Consultations

In most cases of FTT/weight faltering, additional subspecialty consultations are not required. However, if the initial evaluation is concerning for an underlying organic etiology contributing to the patient's poor weight gain, evaluation by a subspecialist may be warranted. The most common pediatric subspecialist that may be involved is pediatric gastroenterology. Consultation should be considered if the patient's initial history, physical examination, and laboratory evaluation suggest a concern for inflammatory bowel disease, cystic fibrosis, celiac disease, or another malabsorptive syndrome that would require endoscopy for further evaluation.[22] In addition, some patients who cannot consume enough calories by mouth may be referred to gastroenterology to consider gastrostomy tube placement to optimize their nutrition.

A key differential diagnosis for FTT is short stature unrelated to nutritional status.[31] In these cases, pediatric endocrinology consultation should be considered for further evaluation. Patients with congenital conditions or other chronic systemic illnesses should be followed by the appropriate subspecialists for their underlying condition. This might include pediatric cardiology, endocrinology, pulmonology, oncology, nephrology, genetics, or infectious disease specialists.

Many patients may benefit from interprofessional consultations to optimize parental education, provide feeding or behavioral therapies, and connect families with additional community support. Options may include consultation with nutrition, social work, and lactation consultants. Enrolling families in nutritional programs such as Women, Infants and Children (WIC), Supplemental Nutrition Assistance Program (SNAP), and New Parent Support/Education programs are also options if needed.[5] Patients with oral-motor dysfunction or feeding refusal may benefit from a consultation with a speech and language pathologist, feeding therapist, or psychologist, depending on the underlying condition.[19] In patients where there is a concern for child abuse or neglect, early consultation with social work, family advocacy/child protective services, and child abuse specialists should be considered.[27][36]

Deterrence and Patient Education

Trending anthropometric data for pediatric patients of all ages is a central component of all primary care well visits. Collecting multiple data points over time and frequent touch points with families can assist the clinician in the early identification of FTT/weight faltering and provide opportunities for parental education.[37] The most common underlying etiology for FTT is inorganic and results from inadequate caloric intake. This is often multifactorial, making it essential to partner with families and offer education about the nutritional needs and common feeding behavior challenges their child may experience at different ages.[18] In addition to baseline caloric and nutritional needs, parental education should offer families strategies to foster a supportive feeding environment.[13] It is also essential to recognize that parents may know and understand their child's nutritional needs but not the resources to meet those needs.[11] For these families, offering parental education and/or consultation with available community and social services resources to help is imperative to successfully preventing and treating FTT.

Enhancing Healthcare Team Outcomes

FTT/weight faltering is best managed by an interprofessional team that includes primary care clinicians, nurses, nutritionists, social workers, and other community partners. In rare cases, pediatric subspecialist consultation may also be warranted.[5] It is a multifactorial condition that, if left untreated, can have significant long-term effects on the growth and development of the pediatric patient.[5] FTT most commonly results from nonorganic etiologies such as inadequate caloric intake due to lack of parental knowledge about nutritional requirements, lack of parental resources to provide needed nutrition, or feeding behaviors leading to inadequate intake. Thus, initial evaluation should start with a thorough history and physical examination before extensive laboratory evaluation.[10]

Accurately collecting and trending anthropometric data over time for pediatric patients is a crucial aspect of prevention and early recognition of FTT. Interprofessional staff should be trained in the proper measurement and scale calibration techniques to ensure accurate data collection. Data should be plotted on age and gender-adjusted growth charts to compare to established norms.[6]

Interprofessional team members contribute a variety of areas of expertise to help diagnose and treat patients with FTT. Often, bedside nurses may have the opportunity to observe feeding practices performed by the family directly and can also comment on the social interactions observed around feeding time. Lactation consultants/nurses are invaluable when treating a mother-infant breastfeeding dyad. Leveraging nurse-driven home visits has been successful in some communities in supporting families and promoting improved weight gain for high-risk patients.[38] 

Calculating caloric requirements to support adequate catch-up growth and addressing any underlying macronutrient or vitamin/mineral deficiencies are often complex. Nutritionists can lend their expertise to identify the right combination of foods and needed volumes to support a healthy growth trajectory.[5] Social workers and community partners can assist the team in identifying resources for families to promote improved access to healthy foods and educational opportunities.[5] In the rare instances of child abuse/neglect, social workers and community partners also assist the team in ensuring the patient has a safe home environment.

Identifying forums for interprofessional team collaboration, such as the patient-centered medical home in primary care or interprofessional patient care conferences in the hospital or subspecialty setting, can effectively enhance team communication and collaboration.[39] Regardless of the underlying etiology of a patient's FTT, optimizing caloric and nutritional intake, offering parental education and support, and monitoring the patient over time to ensure sustained weight gain is the ultimate goal.[7]