Failure to thrive (FTT) is an abnormal pattern of weight gain defined by the lack of sufficient usable nutrition and documented by inadequate weight gain over time. The decrease in the velocity of weight gain results in the child steadily falling off the expected weight curve on growth charts.^1–3 The term weight faltering has been proposed to more appropriately emphasize that problems with appropriate weight gain are the initial and most reliable clinical finding of undernutrition. The term weight faltering is also perceived to be less negative or alarming, and less potentially critical of parents or caretakers.^2,4,5

Although problems achieving or sustaining appropriate weight are the predominant manifestations of FTT, ongoing severe malnutrition impairs overall growth, impacting weight first, then length and head circumference. In extreme cases, the development of cognitive skills and appropriate immune function can be impaired, resulting in failure to achieve developmental milestones and normal health.^2,5,6

Diagnosis

The term FTT should be used as a clinical finding and not as a diagnosis.^4,7 Recognition depends on reliable and valid measurements over time; therefore, serial measurements of weight and height must be accurately obtained and charted on an appropriate reference scale (growth chart).^4–6,8,9 The World Health Organization (WHO) growth charts are recommended for patients up to two years of age (http://www.who.int/childgrowth).^10–13 The Centers for Disease Control and Prevention (CDC) growth charts are recommended for patients two to 20 years of age (http://www.cdc.gov/growthcharts).^11,12 Specialized growth charts can be used in addition to these standard charts for supplemental data collection in children born prematurely or with specific diagnoses, such as Turner syndrome or trisomy 21.^13,14

Although there is no consensus on the definition of childhood FTT, the term is often used for infants and children with weight below the 5th percentile for sex and corrected age.¹⁵ Supporting definitions include weight for length below the 5th percentile; body mass index for age below the 5th percentile³; or a sustained decrease in growth velocity, in which weight for age or weight for length/height falls by two major percentiles (percentile markers 95, 90, 75, 50, 25, 10, and 5) over time.¹⁵

The prevalence of FTT depends on the population studied and recognition criteria used. In the United States, FTT may occur in up to 10% of children in primary care and in approximately 5% of children who are hospitalized.^4,15 The rate of detection depends on the vigilance of individual physicians.¹⁶

Etiology

The most common cause of FTT is inadequate caloric intake. Other causes are inadequate nutrient absorption, increased energy requirements (metabolic demands), or a combination of mechanisms. Specific causes of FTT are listed in Table 1. Risk factors for FTT are traditionally classified as psychosocial or medical (Table 2⁵ ), although FTT is commonly caused by multiple complex factors resulting in inadequate caloric intake. The prevalence of various causes of FTT may differ based on the patient's age and the underlying cause.

Diagnostic Evaluation

FTT can be confirmed based on a detailed history, physical examination, and growth parameters documented over time. Targeted laboratory and other diagnostic testing should be performed when there is reasonable suspicion of a specific underlying condition.

HISTORY

The key elements of the history include a nutritional evaluation and medical, family, and social histories (Table 3). The nutritional evaluation requires obtaining information about caloric intake and overall nutritional quality from the caregivers who feed the patient. Food diaries can help quantify intake and identify dysfunctional mealtimes, grazing habits, lack of a routine or schedule, distractions during feeding, and inappropriate caretaker responses to the child's feeding behaviors.^13,17,18 A common problem in toddlers is excessive intake of nutrition-poor liquids, such as “fruit” juice that is predominantly flavored sugar water, that produce satiety before nutritious foods can be consumed.¹⁹

A brief developmental evaluation using any standard validated questionnaire helps to identify patients with potential developmental abnormalities contributing to FTT. Abnormal development may be an early indicator of an underlying medical condition, such as a neuromuscular disorder or a psychosocial problem, such as neglect, that can contribute to or exacerbate FTT. Also, children with FTT have a higher incidence of developmental delay.²⁰ The assessment provides a baseline for ongoing monitoring of development that may be impacted by severe nutritional compromise. One example of a free tool for monitoring development is the Rourke Baby Record from Canada (available at http://www.rourkebabyrecord.ca).²¹

PHYSICAL EXAMINATION

The goals of the physical examination are identification of any chronic or acute illness, recognition of dysmorphology suggesting a genetic condition, assessment for normal development, and quantification of the degree of undernutrition. Table 4 includes key physical examination findings in children with FTT. Underlying medical problems need to be appropriately treated. The physical condition of the child and any comorbid conditions determine the subsequent steps in management.

DIAGNOSTIC TESTING

No standard set of laboratory tests is recommended for FTT. A thorough history and physical examination may be all that is indicated to initiate treatment.^5,22 If used, reasonable initial laboratory testing includes complete blood count, urinalysis, electrolyte measurement, thyroid tests, and testing for celiac disease. Specific testing for cystic fibrosis, food allergies, human immunodeficiency virus infection, or tuberculosis may be indicated depending on the presentation. Additional testing should be specific for a suspected diagnosis based on history and physical examination findings.

Treatment

The goal of treatment is to establish optimal growth velocity while supporting the family in the plan of care. Prolonged malnutrition can negatively impact growth potential and cognitive development.^1,2 Early intervention that results in corrected growth parameters is believed to lead to positive developmental outcomes, but further studies are needed.^2,16 Primary care physicians can treat most patients with FTT in the outpatient setting. If usual treatment is insufficient, support from additional health care professionals, such as a dietitian, social worker, dentist, or lactation specialist, may be helpful.

Attention to several specific health factors is needed to ensure overall treatment success. Dental caries should be treated. Sleep disorders or problems should be identified and addressed because poor sleep can contribute to poor activity and behavior, and subsequently poor nutrition.²³ Parents of children who are being treated for FTT should be counseled on sick care management and the importance of encouraging a regular balanced diet. Home nursing visits can complement clinic evaluations, especially for families who have difficulty with transportation or getting time off of work. Families with problems obtaining nutritious foods (food insecurity) should be provided with social work support or other community resources, such as the Women, Infants, and Children program.

Pharmacotherapy, such as cyproheptadine or megestrol (Megace), has been studied and may be helpful for specific populations with significant underlying diseases (e.g., cystic fibrosis, chronic renal disease) or in patients undergoing cancer treatment.^24–26 However, appetite stimulants are not recommended for most patients with FTT.

Catch-up growth will occur when the child gains at two to three times the average rate per age⁵ (eTable A). eTable B shows one method for calculating catch-up calorie needs. For infants, an evaluation of breastfeeding and lactation or an adjustment in formula concentration is indicated if inadequate caloric intake is responsible for FTT. eTable C shows formula recipes for increasing calories. Without performing complicated calculations, most infants will tolerate increasing formula concentration from 19 to 24 kcal per oz. Caregivers of toddlers and older children should be counseled on nutrient-rich, healthy food choices, ideally provided in three meals and three snacks per day.⁵

Follow-up visits ranging from weekly to every few months are used to document weight, and the plan should be adjusted as the child progresses. These frequent visits provide opportunities to ensure that immunizations are up to date to support the child's immune system. Infants need more frequent follow-up than older children. Daily weight checks at home or in the office are discouraged. Weight change is better averaged over intervals of a few days to weeks until normal growth velocity is achieved. When weight checks occur over a short interval (e.g., during a hospital stay) they should occur on the same scale and at the same time of day, before feedings and with consistent dress. When weight is checked in the office, a routinely calibrated scale and consistent technique should be used.

Hospitalization is rarely indicated^5,22,27 but can facilitate subspecialist involvement and provide observed structured feeding evaluations. Table 5 includes indications for hospitalization. Hospitalization should be considered if the child is at severe health risk. Hospitalization or subspecialist referral should be considered if intensive outpatient treatment is ineffective after three to four months, or sooner for newborns.³ Children with complex medical, developmental, and social problems may show weight gain in the hospital setting because of the support of the highly trained multidisciplinary medical staff. Weight gain in the hospital does not necessarily confirm inadequate feeding or care by the family as the cause of FTT. Successful hospitalization requires careful integration of the child's usual caretakers in the patient's care and discharge planning.

Accelerated growth must be maintained for four to nine months to resolve FTT and achieve appropriate weight for height. Weight for height measurements above the 10th percentile with normal weight gain on two evaluations at least one month apart are reassuring for successful treatment.⁵ Relapses are possible, and continued observation is needed after successful completion of the frequent visit schedule. The risk of relapse is increased if the underlying etiology is not adequately addressed. Once FTT is resolved, patients require standard well visits with emphasis on monitoring for nutrition and growth.^9,16

Prevention

Routine health surveillance visits in early childhood give primary care physicians opportunities to counsel and educate families on nutrition. Risk factors for FTT can also be identified and addressed. The American Academy of Pediatrics' Bright Futures series has helpful nutrition information for children in different age groups.²⁸

Data Sources: A PubMed search was completed using the key terms pediatric failure to thrive and pediatric weight faltering. The search included meta analyses, reviews, randomized controlled trials, and clinical trials. Additional searches included UpToDate, Essential Evidence Plus, the Cochrane database, and evidence-based guidelines from the National Guideline Clearinghouse, American Academy of Pediatrics, and Centers for Disease Control and Prevention. Search dates: July and December 2015.

The author thanks Drs. Anne Walling, Brian M. Pate, Kari Harris, and Deborah Kroeker for their review and helpful comments during the preparation of the manuscript.

note: This review updates a previous article on this topic by Cole and Lanham.³