Poor weight gain in children older than two years in resource-abundant settings

INTRODUCTION — In most cases, poor weight gain in preschool and school-age children is the consequence of inadequate dietary nutrient intake relative to typical needs for metabolism and growth. In other cases, poor weight gain is related to increased metabolic requirements secondary to an underlying disease state, or a combination of these factors. The challenge for the child's clinician is to determine if inadequate dietary intake is the result of an underlying medical problem (organic disease), environmental or psychosocial problems, or a combination of these factors.

This topic will discuss the etiology and approach to poor weight gain in children older than two years in resource-abundant settings. Poor weight gain in children younger than two years and other issues related to nutrition and undernutrition in children in resource-abundant and resource-limited settings are discussed separately:

●(See "Poor weight gain in children younger than two years in resource-abundant settings: Etiology and evaluation".)

●(See "Poor weight gain in children younger than two years in resource-abundant settings: Management".)

●(See "Estimation of dietary energy requirements in children and adolescents".)

●(See "Vegetarian diets for children".)

●(See "Causes of short stature".)

●(See "Diagnostic approach to children and adolescents with short stature".)

●(See "Malnutrition in children in resource-limited settings: Clinical assessment".)

●(See "Management of moderate acute malnutrition in children in resource-limited settings".)

●(See "Management of uncomplicated severe acute malnutrition in children in resource-limited settings".)

●(See "Management of complicated severe acute malnutrition in children in resource-limited settings".)

BACKGROUND — Weight gain follows a predictable course from infancy through adolescence. Height and weight should be assessed routinely and compared with antecedent measurements.

Whenever significant voluntary or involuntary weight loss occurs as described below, or when the rate of weight gain varies from the previously established pattern, there is cause for concern [1]. Any deviation in the pattern of weight gain, when compared with the standardized growth curves from the National Center for Health Statistics (figure 1A-B) should be evaluated. (See "Measurement of growth in children".)

DEFINITION — Poor weight gain refers to two types of growth failure in the preschool and school-age child:

●Abrupt weight loss following a period of normal growth along a well-established pattern of height and weight gain.

●Slow, albeit steady, weight gain that tracks along a growth channel either well below the fifth percentile of the National Center for Health Statistics weight-for-age growth curves (figure 1A-B) or a weight curve proportionate to, but lower than, the child's height trajectory (figure 2A-B).

In either case, the definition of poor weight gain relies on the availability of serial weight measurements over a 6- to 12-month period of time.

EPIDEMIOLOGY — Poor weight gain is a common concern in pediatric practice. However, the precise frequency is unknown, since poor weight gain may be both over- and underdiagnosed. The caregivers' level of concern regarding their child's weight gain may reflect expectations based upon the caregivers' recollections of their own patterns of growth, whereas clinicians may have limited concerns about a child's gradual decline or slow gain in weight.

ETIOLOGY — The primary cause of poor weight gain in preschool and school-age children and adolescents is inadequate dietary intake relative to typical metabolic and growth needs [2]. The etiology of inadequate dietary intake often is mixed; underlying medical conditions and environmental or psychosocial problems play a role [3,4]. Involuntary weight loss typically implies an underlying medical problem, whereas slow weight gain is more often related to social and/or environmental factors. However, there are exceptions (eg, inflammatory bowel disease (IBD) often presents with slow weight gain rather than weight loss). (See "Growth failure and pubertal delay in children with inflammatory bowel disease".)

Factors contributing to inadequate dietary intake include poverty, lack of understanding on the part of the caregivers regarding the nutritional needs of children, oromotor dysfunction, increased metabolic needs, malabsorption, increased excretory losses, and the energy cost of growth itself [4]. When inadequate intake is related to an underlying medical condition, the gastrointestinal, cardiac, and renal systems are those most commonly involved (in decreasing order of frequency) [5].

Limited or inappropriate intake — Limited or inappropriate intake of food can be involuntary or deliberate. Causes include:

●Poverty with inadequate or inconsistent food supply.

●Discomfort or pain associated with eating (eg, in children with gastroesophageal reflux, esophagitis, dental caries, chronic constipation) [6-8]. (See "Clinical manifestations and diagnosis of gastroesophageal reflux disease in children and adolescents".)

●Oromotor dysfunction – Problems with chewing and swallowing are common in children with central nervous system or neuromuscular disorders [9]. Although oral motor dysfunction is unlikely to develop anew in a child older than two years without an underlying medical condition, it may become more apparent in the older child as the medical condition changes.

●Behavioral issues:

•Toddlers may develop a feeding aversion because of poor caregiver-child interactions where issues of control dominate; these dietary control issues are a frequent component of poor weight gain. Food aversion also can be a learned behavior related to sensations associated with food textures, consistencies, temperatures, or smells [10].

•Children between the ages of two and five years may become "picky" or "selective" eaters [11]. At this age, increased exploratory activities may limit the time a child focuses on eating. Strange eating habits or limited intakes of a variety of foods and beverages generally are a temporary developmental phase and may be causally related to the normal pattern of slower growth at this age. (See "Dietary recommendations for toddlers and preschool and school-age children", section on 'Preschool children'.)

However, if other causes of picky eating (eg, gastroesophageal reflux, constipation, etc) have been excluded, selective eating in the context of poor weight gain may be a marker for psychosocial problems, including poor caregiver-child interactions, or may indicate an eating disorder: avoidant/restrictive food intake disorder [12]. (See 'Indications for referral' below and "Eating disorders: Overview of epidemiology, clinical features, and diagnosis", section on 'Avoidant/restrictive food intake disorder'.)

•Other behavioral issues that can affect dietary intake include hyperactivity and attention problems (which may decrease time spent eating), as well as anorexia nervosa and bulimia nervosa [13]. (See "Eating disorders: Overview of epidemiology, clinical features, and diagnosis".)

●Decreased appetite – Decreased appetite can occur for a variety of reasons:

•Toddlers may ingest too much juice or other nonnutritious liquid, resulting in satiation and decreased appetite for higher caloric density or more nutritious solid foods [14]. (See "Dietary recommendations for toddlers and preschool and school-age children", section on 'Fruits, vegetables, and fruit juice'.)

•Children with any chronic disease, including gastrointestinal (eg, celiac disease, lactose intolerance, IBD), renal, cardiac, or pulmonary conditions, may have anorexia, vomiting, early satiety, abdominal pain, constipation, or diarrhea [15].

•Medications (eg, for seizures or attention deficit disorder) [16,17].

•Stressful psychosocial conditions.

●Dietary restriction – Older children and adolescents may impose limits on their dietary intake in an effort to lose weight or be healthy. Eating disorders may develop [18]. (See "Eating disorders: Overview of epidemiology, clinical features, and diagnosis".)

Dietary restriction also may be related to actual or perceived food intolerance or allergy and cultural or personal beliefs [19-22]. Restrictive diets (eg, dairy-free, vegetarian, low-fat, low-carbohydrate) may not supply all the energy and nutrient needs for a growing child or adolescent [23,24]. (See "Vegetarian diets for children".)

●Child abuse [25]. (See "Child neglect: Evaluation and management", section on 'Clinical presentations'.)

Increased needs

●Increased metabolic rates – Children with underlying medical conditions may have increased total daily energy expenditure because of increased resting metabolic rates or energy costs associated with activity or inflammation [26-29].

•Congenital heart disease is associated with poor weight gain because of increased total daily energy expenditure in infants [26,27]. Although hypoxia is thought to contribute to their poor weight gain, vomiting, alterations in carbohydrate and fat metabolism, and the energy cost of physical activity may explain the higher energy needs of infants with congenital heart disease. Presumably, these factors account for poor weight gain in the toddler and older child, as well.

•Infants with chronic lung disease experience marked stress during the early stages of disease [28]. If lung disease persists, toddlers and older children may have increased energy expenditure because of increased work of breathing and recurrent respiratory illnesses. Increased energy expenditure may be the consequence of physiologic stress as indicated by increased serum catecholamines [29].

•Hyperthyroidism is associated with increased heart rate and blood pressure, but the mechanisms responsible for thyroid-hormone-controlled energy expenditure have not been elucidated [30]. (See "Clinical manifestations and diagnosis of Graves disease in children and adolescents".)

•Obstructive sleep apnea may be associated with increased energy expenditure because of the increased work of breathing during sleep [31,32]. (See "Evaluation of suspected obstructive sleep apnea in children", section on 'Examination'.)

•Diencephalic syndrome, a disorder associated with central nervous system tumors, is a rare cause of profound weight loss related to increased energy expenditure but should not be overlooked [33-35].

●Inflammation – Diseases that have an inflammatory or catabolic component, such as cystic fibrosis, IBD, or malignancy, may be associated with weight loss and subsequently poor weight gain. Increased inflammatory cytokines may stimulate the release of leptin, a satiety factor that leads to poor weight gain in some of these disorders [36]. (See "Cystic fibrosis: Clinical manifestations and diagnosis" and "Growth failure and pubertal delay in children with inflammatory bowel disease".)

●Increased activity – The fidgety, hyperactive, or "busy" child may expend more energy. However, this increase in physical activity is a debatable cause of poor weight gain [37].

Increased losses — Increased losses of nutrients in the stool or urine or as a result of vomiting may occur as a consequence of several medical conditions, including:

●Celiac disease (see "Epidemiology, pathogenesis, and clinical manifestations of celiac disease in children")

●IBD (see "Growth failure and pubertal delay in children with inflammatory bowel disease")

●Cystic fibrosis (see "Cystic fibrosis: Clinical manifestations and diagnosis")

●Bulimia nervosa [13] (see "Eating disorders: Overview of epidemiology, clinical features, and diagnosis", section on 'Bulimia nervosa')

●Short bowel syndrome (see "Chronic complications of short bowel syndrome in children")

●Eosinophilic gastrointestinal disorders (see "Eosinophilic gastrointestinal diseases")

●Pancreatitis (see "Clinical manifestations and diagnosis of chronic and acute recurrent pancreatitis in children", section on 'Malabsorption')

●Chronic liver disease

●Diabetes mellitus (see "Epidemiology, presentation, and diagnosis of type 1 diabetes mellitus in children and adolescents")

●Chronic renal disease (see "Chronic kidney disease in children: Complications")

●Inborn errors of metabolism (see "Inborn errors of metabolism: Epidemiology, pathogenesis, and clinical features", section on 'Gastrointestinal')

●Renal tubular acidosis (see "Etiology and clinical manifestations of renal tubular acidosis in infants and children" and "Etiology and clinical manifestations of renal tubular acidosis in infants and children", section on 'Clinical manifestations')

●Protein sensitivity (allergy) (see "Food protein-induced enterocolitis syndrome (FPIES)")

●Carbohydrate intolerance (see "Lactose intolerance and malabsorption: Clinical manifestations, diagnosis, and management" and "Causes of hypoglycemia in infants and children")

A more advanced evaluation may be required if screening studies are suggestive of these disorders. (See 'Advanced tests' below.)

Energy cost of growth — Children who are underweight have substantially increased energy requirements to achieve catch-up growth. The energy cost of growth often is underestimated. Coupled with poor dietary intake, the energy cost of growth further aggravates progressive deficits in body weight prior to linear growth arrest. The daily energy cost of growth averages 5 kilocalories per gram of tissue accreted [38].

DIAGNOSTIC APPROACH

Overview — The conceptual framework for the diagnostic approach to poor weight gain depends upon the practice pattern of the clinician. The primary care clinician frequently searches for common problems that have less severe presentations, whereas the specialist seeks to diagnose or exclude uncommon disorders that have significant medical consequences.

In either case, the usual approach is to identify the major symptoms, consider the most common categories of disease possibilities, conduct a thorough physical examination, screen for possible disease entities, begin an empiric treatment regimen, and monitor the clinical response [39,40]. The pace of the evaluation should be individualized and tailored to the severity of the problem.

Obtaining accurate serial weight and height measurements using appropriate measuring devices is essential to establish the validity and pattern of poor weight gain. In general, inadequate caloric intake affects weight gain first, then height velocity and height percentiles. It is generally necessary to monitor weight and height for at least six months before concluding that a patient has met the definition of poor weight gain. (See 'Definition' above.)

During this period, the primary care clinician may rely on simple interventional strategies (eg, nutritional counseling and dietary intervention) or systematically perform a series of diagnostic tests to help determine whether the child has an underlying medical problem in addition to contributing psychosocial or environmental factors. The primary care clinician may refer the child to the specialist when advanced diagnostic studies are required. (See 'Management' below and 'Diagnostic evaluation' below.)

History — The interview process with the caregiver, in conjunction with casual observation of the child's behavior and social interactions between the caregiver and child, often provides clues about the potential contributing factors.

Present illness — Inadequate dietary intake relative to metabolic and growth needs, regardless of the cause, is the most common reason for poor weight gain. Thus, the medical history should focus on:

●Problems that affect appetite

●Eating patterns and behaviors

●Chewing and swallowing difficulties

●Diagnoses that reflect poor gastrointestinal motility, such as gastroesophageal reflux or delayed gastric emptying [41]

●Diarrhea, particularly if features of malabsorption can be identified

●Constipation, in which features of fecal impaction or pronounced bloating may disturb the child's appetite

If the review of systems or other aspects of the initial evaluation suggest a problem unrelated to the gastrointestinal tract, other causes of poor weight gain should be considered (table 1).

Diet history — Caregiver report of the child's daily dietary intake is helpful but may be inaccurate. Caregiver perceptions often result in over- or underestimation of intake [42]. A three-day record of the child's food and beverage consumption, as well as the use of vitamin and mineral supplements, may be more informative than simple caregiver report if caregivers are able to comply with the requirements for accurate record keeping. (See "Dietary history and recommended dietary intake in children", section on 'Dietary diary'.)

Assessment of the child's appetite, eating schedule, and behaviors associated with meals provides insight into feeding problems [43-45]. Feeding problems in young children are common. Feeding problems can include picky eating, food refusal, not self-feeding appropriate for age, and anorexia. Most serious feeding problems occur in children who have other medical, behavioral, or developmental problems. In most cases, these conditions interfere with a child's ability to feed as the result of structural abnormalities of the face, oral cavity, or aerodigestive system, neuromuscular dysfunction, or nausea and discomfort during the feeding process. It is also important to ask about caregiver responses to the child's eating patterns to assess the feeding relationship. Feeding questionnaires may provide meaningful information about feeding difficulties in children [46,47].

Past history

●Perinatal – The perinatal history should include information regarding complications during the pregnancy or delivery, gestational age and birth weight, exposures to toxins (eg, alcohol, anticonvulsants) or infectious organisms in utero, the method of feeding the child during the early postnatal period, and any clinical problems during the first postnatal year.

●Growth and developmental – Important questions in the growth and developmental history include:

•Has the child's weight always been below the growth curve?

•Was the child gaining normally, then slowed down, or did the child have an abrupt loss of weight?

•What triggered the change in the growth pattern? Did it coincide with major psychosocial stressors (eg, parental divorce, maltreatment), new symptoms, or a new diagnosis?

•Did the child acquire developmental milestones on schedule?

Social history — Many psychosocial issues such as poverty, young parental age, depression, alcohol or drug abuse, mental illness, and violence may contribute to food insecurity and, consequently, to poor weight gain in children. In addition, the coronavirus disease 2019 (COVID-19) pandemic has aggravated the pattern of food insecurity which disproportionately affects children [48]. Observing the interactions between the caregiver and child may offer insight into the etiology of the child's abnormal growth pattern.

Families at risk for food insecurity can be identified by asking [49]:

●"Within the past 12 months we worried whether our food would run out before we got money to buy more."

●"Within the past 12 months the food we bought just didn't last, and we didn't have money to get more."

Endorsement of either of these questions as often or sometimes true rather than never true is an accurate indication of food insecurity [49-52]. (See "Screening tests in children and adolescents", section on 'Screening for poverty'.)

In the United States, resources that can be provided to families with food insecurity include [50]:

●2-1-1 – Provides information about school lunch programs, summer food programs, soup kitchens, community gardens, and government-sponsored food programs

●Feeding America – Provides a food bank locator and other resources households without enough food

●MyPlate – Provides tip sheets and recipes for healthy eating at low cost

Family history — An assessment of familial growth patterns and the determination of midparental height may redirect concerns or provide reassurance. As an example, if the child's actual height is two growth channels below the expected midparental height (calculator 1), further evaluation should be considered. Conversely, if the child's growth is slow for their age, but consistent with midparental height, reassurance and monitoring are appropriate. A review of familial medical problems, especially those that might be inherited or shared, is essential. (See "Normal growth patterns in infants and prepubertal children", section on 'Predicted height'.)

Review of systems — The review of systems should focus on symptoms and signs of problems that can lead to limited intake, poor utilization or malabsorption of nutrients, and increased metabolic needs (table 1). Common symptoms or signs of concern include early satiety, dental caries, difficulty chewing and swallowing, vomiting, bloating, diarrhea, and constipation.

Physical examination — The physical examination of the child with poor weight gain rarely reveals classic diagnostic signs of specific clinical entities. The clinical features of poor weight gain may be limited to decreased subcutaneous fat and muscle mass. Nonetheless, it is important to look for signs of an underlying medical condition (table 2), anatomic abnormality, nutrient deficiency, abuse or neglect, and developmental or neurologic problems.

Growth parameters — Accurate assessment of weight, height, body mass index (BMI), and weight-for-height compared with population standards is an important aspect of the physical examination. (See "The pediatric physical examination: General principles and standard measurements", section on 'Growth parameters'.)

●Body weight is obtained using a calibrated, age-appropriate scale, once heavy clothing has been removed. It is plotted on an age- and sex-appropriate growth chart (figure 1A-B).

●Standing height is measured without shoes using the four-point stance, with an appropriate measuring device that includes a movable perpendicular head piece (figure 3). It is plotted on an age- and sex-appropriate growth chart (figure 1A-B and figure 2A-B and figure 4A-B).

●The BMI is calculated from the weight and square of the height as follows (calculator 2 and calculator 3):

BMI is plotted on an age- and sex-appropriate growth chart (figure 4A-B).

●Weight-for-height percentile (available from the Centers for Disease Control and Prevention for males and females)

An alternative approach is the use of z-score charts. Z-scores describe the degree to which a measurement deviates from the mean of a population standard so they are particularly useful for measurements at the extremes of a distribution (<3^rd or >97^th percentile) or when comparing populations that use different standards (figure 5). (See "Measurement of growth in children", section on 'Use of Z-scores'.)

It is critical to obtain information about previous growth parameters. Single assessments of height, weight, and BMI have limited usefulness because they do not provide sufficient information to characterize the pattern of poor weight gain.

The differential diagnosis of poor weight gain is based upon current growth measurements and the pattern of growth failure. As examples:

●Acute weight loss, with normal height velocity, may be due to inadequate dietary intake or the onset of a new illness.

●Decreased rates of growth in both weight and height are more likely due to a chronic condition.

●Normal height and weight velocities that follow the standard National Center for Health Statistics growth curves but are below the third to fifth percentiles may be normal variations (eg, familial short stature or constitutional delay of growth) or may have an endocrinologic or psychosocial etiology. (See "Diagnostic approach to children and adolescents with short stature", section on 'Are there features that suggest that this is a normal variant of short stature?'.)

General examination — General examination findings that may provide a clue to underlying medical illness include:

●Abnormal breath sounds may suggest chronic lung disease (eg, cystic fibrosis)

●A cardiac murmur may suggest congenital heart disease

●Hepatomegaly with or without splenomegaly may indicate chronic liver disease

●Abdominal distention may be associated with malabsorption, small bowel bacterial overgrowth, or giardiasis (see "Approach to the adult patient with suspected malabsorption" and "Small intestinal bacterial overgrowth: Clinical manifestations and diagnosis" and "Giardiasis: Epidemiology, clinical manifestations, and diagnosis")

Diagnostic evaluation — Laboratory tests and imaging studies are unlikely to lead to the diagnosis of an underlying medical disorder in the absence of findings from the medical history or physical examination [3]. However, selective screening studies may provide reassurance that certain conditions are unlikely to be present.

Laboratory tests and diagnostic imaging studies should be performed in a step-wise and focused manner. Specialized testing may be warranted if an etiology has not been found and the patient does not respond to dietary or behavior modification.

Initial tests — The initial (baseline) tests in the evaluation of poor weight gain in children older than two years may include:

●Complete blood count, C-reactive protein, and erythrocyte sedimentation rate as a screen for anemia, chronic infection, inflammation, and malignancy

The red blood cell indices, reticulocyte count, and blood smear guide the further evaluation of anemia, which is discussed separately. (See "Approach to the child with anemia", section on 'Evaluation'.)

●Urinalysis and culture as a screen for protein or carbohydrate loss (eg, glucosuria in type 1 diabetes mellitus) and indolent renal disease, such as chronic urinary tract infection or renal tubular acidosis

●Tissue transglutaminase and serum immunoglobulin (Ig) A as a screen for celiac disease (see "Diagnosis of celiac disease in children", section on 'Tissue transglutaminase antibodies')

Additional tests — Additional laboratory tests or imaging studies may be necessary in the initial evaluation if the history and/or examination suggest particular conditions. The additional tests that may be warranted include:

●Electrolytes, blood urea nitrogen, creatinine, glucose, calcium, phosphorus, magnesium, albumin, total protein, liver enzymes, amylase, lipase – These should be obtained to evaluate kidney (eg, renal tubular acidosis), liver, and pancreatic function

These tests also provide an indication of nutritional status; they are commonly obtained by primary care clinicians in children with poor weight gain and specific risk factors. (See "Laboratory and radiologic evaluation of nutritional status in children", section on 'Undernourished children'.)

●Specific vitamin levels should be obtained in children with certain conditions. As examples:

•Vitamin B12 and folate levels for those on strict vegetarian or vegan diets or with known or suspected inflammatory bowel disease (see "Vegetarian diets for children", section on 'Vitamin B12' and "Vitamin and mineral deficiencies in inflammatory bowel disease", section on 'Vitamin B12')

•Vitamin D levels for those with limited outdoor time and those with physical disabilities (see "Vitamin D insufficiency and deficiency in children and adolescents", section on 'Pathogenesis and risk factors')

●Stool or 13C-urea breath test for Helicobacter pylori if H. pylori disease is suspected (see "Indications and diagnostic tests for Helicobacter pylori infection in adults", section on 'Noninvasive testing')

●Stool studies including guaiac, leukocytes, routine culture, ova and parasite smears, and/or Giardia antigen if gastrointestinal infection is suspected (see "Giardiasis: Epidemiology, clinical manifestations, and diagnosis")

●Stool studies including guaiac, leukocytes, and calprotectin if inflammatory bowel disease (IBD) is suspected (see "Clinical presentation and diagnosis of inflammatory bowel disease in children", section on 'Stool tests')

●Stool-reducing substances if malabsorption of carbohydrates is suspected, alpha-1 antitrypsin if protein-losing enteropathy is suspected, and elastase if fat malabsorption or pancreatic insufficiency is suspected (see "Approach to the adult patient with suspected malabsorption")

●Thyroid studies if there are symptoms or signs of hyperthyroidism (see "Clinical manifestations and diagnosis of Graves disease in children and adolescents")

●Tuberculin skin testing if tuberculosis is suspected (see "Tuberculosis infection (latent tuberculosis) in children" and "Tuberculosis disease in children: Epidemiology, clinical manifestations, and diagnosis")

●Chest radiograph if cardiac or pulmonary disease is suspected

Advanced tests — Specialized testing may be warranted if certain diagnoses are suspected or if an etiology has not been found and the patient has not responded to dietary or behavior modification. Specialized testing may include:

●Human immunodeficiency virus (HIV) test (see "Screening and diagnostic testing for HIV infection", section on 'Testing algorithm')

●IBD panel for anti-Saccharomyces cerevisiae antibodies (ASCA), perinuclear antineutrophil cytoplasmic antibodies (p-ANCA), and anti-OmpC antibodies (see "Clinical presentation and diagnosis of inflammatory bowel disease in children")

●Serum IgE, radioallergosorbent tests (RAST), and skin tests to selected food antigens (see "Clinical manifestations of food allergy: An overview" and "Diagnostic evaluation of IgE-mediated food allergy")

●Serum antinuclear antibodies (ANA) anti-liver-kidney microsomal (anti-LKM), and anti-double-stranded (ds)DNA antibodies as markers for autoimmune disease (eg, autoimmune hepatitis) (see "Overview of autoimmune hepatitis")

●Hepatitis (A, B, C) panel (see "Overview of hepatitis A virus infection in children" and "Clinical manifestations and diagnosis of hepatitis B virus infection in children and adolescents" and "Hepatitis C virus infection in children")

●Cytomegalovirus and Epstein-Barr virus; IgM and IgG. (see "Overview of cytomegalovirus infections in children" and "Clinical manifestations and treatment of Epstein-Barr virus infection")

●Testing for inborn errors of metabolism, storage diseases, or chromosomal abnormalities (eg, serum amino acids, urine organic acids, urine-reducing substances, serum carnitine profile, chromosomes) (see "Metabolic emergencies in suspected inborn errors of metabolism: Presentation, evaluation, and management")

●Advanced endocrine evaluation, particularly growth hormone [53] (see "Diagnosis of growth hormone deficiency in children")

●Sweat chloride test (see "Cystic fibrosis: Clinical manifestations and diagnosis")

●Upper gastrointestinal series with small bowel follow through if IBD is suspected

●Swallowing function study if swallowing dysfunction or aspiration is suspected

●Advanced diagnostic imaging studies, such as abdominal ultrasound, radionuclide scans for gastric and biliary tract emptying, and abdominal and head computed tomography scans, to evaluate the presence of intra-abdominal and intracranial processes that may affect appetite or cause vomiting

●Advanced endoscopic studies with biopsies, including duodenoscopy, colonoscopy, small bowel capsule enteroscopy [54] (see "Clinical manifestations and diagnosis of gastroesophageal reflux disease in children and adolescents" and "Clinical presentation and diagnosis of inflammatory bowel disease in children" and "Acute and chronic gastritis due to Helicobacter pylori" and "Peptic ulcer disease: Clinical manifestations and diagnosis" and "Diagnosis of celiac disease in children")

MANAGEMENT — The management of poor weight gain in children older than two years of age depends upon the clinical findings and results of diagnostic studies. The approach to treatment often is multifaceted [4]. The response to intervention aids in the diagnostic process.

Indications for hospitalization — Hospitalization is warranted for any of the following:

●The child is moderately to severely malnourished (eg, weight-for-age z-score <-2 [approximately 2^nd percentile], weight-for-height <80 percent of the median, or body mass index (BMI) <12 kg/m²) [55,56]

●Serious organic cause is suspected (eg, malignancy)

●Concern for neglect or abuse

●Eating patterns need to be observed

Otherwise, most cases can be handled on an outpatient basis [3]. Any medical conditions that are discovered should be treated appropriately.

In resource-limited settings, most cases of uncomplicated moderate or severe malnutrition are effectively managed in outpatient feeding programs. (See "Management of uncomplicated severe acute malnutrition in children in resource-limited settings".)

Dietary intervention — Nutritional counseling and dietary intervention are the first steps to therapy and should begin during the evaluation [57]. Dietary interventions are based on increasing the intake of foods and beverages that have increased caloric density.

●Children can increase their dietary energy intake by supplementing foods with margarine, honey, syrups, gravies, creams, oils, cheese, peanut butter, avocados, and ice cream.

●Caregivers should offer the child two to three mini-meals in addition to three well-balanced meals daily.

●Beverage intake should be discussed. When children drink too much they may feel full and decrease the intake of solid foods. The intake of nonnutritious sugary beverages and juices should be minimized. Milk consumption should be tailored to the patient's age (16 to 24 ounces per day maximum).

●Caregivers may offer commercially available formulas and puddings to supplement the child's intake if the child is not able to eat enough nutrient-dense foods to gain weight adequately. These supplements should not be offered near mealtime, since the goal is to add additional calories without suppressing the child's appetite for meals.

●The use of supplemental multivitamins and minerals is prudent.

Height and weight velocities, as well as changes in BMI, should be followed closely. If the child increases their dietary intake sufficiently, catch-up weight gain should be accomplished in a three- to six-month time frame.

Behavioral management — Mealtime behavior should be structured and distractions should be minimized. The child should be encouraged to try a variety of foods. Caregivers should keep mealtime enjoyable and avoid punishing the child or forcing the child to finish portions of all foods offered. Families should be encouraged to eat meals together and model healthy eating behaviors.

Indications for referral — Psychosocial problems may require consultation with a behavioral psychologist or social worker. Families may need a referral to social services for financial assistance or to a clinical therapist for management of mental and behavioral problems. Occupational or speech therapy may be required for the treatment of oral motor or swallowing problems.

Most preschool and school-age children with poor weight gain can be managed by their primary care provider once the factors contributing to inadequate dietary intake are identified [3]. A registered dietitian may provide helpful guidance related to food and beverage selections, portion sizes, nutrient density of foods and beverages, and creative ways to incorporate nutrient dense foods into the child's diet.

Referral to a specialist may be indicated for children in whom advanced diagnostic studies are required and for those in whom underlying medical conditions are identified. In cases where there is concern for an eating disorder, referral to a mental health provider or adolescent specialist may be warranted.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Poor weight gain in infants and children".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or email these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient education" and the keyword[s] of interest.)

●Basics topic (see "Patient education: Poor weight gain in babies and children (The Basics)")

●Beyond the Basics topic (see "Patient education: Poor weight gain in infants and children (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●Definition – Poor weight gain refers to abrupt weight loss following a period of normal growth along a well-established pattern, or weight gain that tracks along a growth channel either well below the fifth percentile of the growth curves (figure 1A-B) or a growth curve proportionate to, but lower than, the child's expected height trajectory (figure 2A-B). (See 'Definition' above.)

●Etiology – The primary cause of poor weight gain in preschool and school-age children and adolescents is inadequate dietary intake relative to typical metabolic and growth needs, which may be related to underlying medical, environmental, or social problems, alone or in combination. (See 'Etiology' above.)

●Diagnostic approach – The diagnostic approach typically involves performing a complete history and physical examination to identify the major symptoms (table 1) and etiologic categories (table 2), screening for possible disease entities, initiating an empiric treatment regimen, and monitoring the clinical response. The pace of the evaluation is tailored to the severity of the problem. (See 'Diagnostic approach' above.)

The most important aspects of the physical examination are the growth measurements and the growth pattern. The pattern of growth helps to narrow the differential diagnosis. (See 'Growth parameters' above.)

●Management – Nutritional counseling and dietary intervention are the first steps to therapy and should begin during the evaluation. If the child increases their dietary intake sufficiently, catch-up weight gain should be accomplished in a three- to six-month time frame. (See 'Management' above.)

ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges Kathleen J Motil, MD, PhD, who contributed to earlier versions of this topic review.