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, malabsorption of calories, 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.

Acute or progressive unintentional weight loss often indicates a serious medical illness; the evaluation and management are discussed in a separate topic review. (See "Evaluation of weight loss in infants over six months of age, children, and adolescents".)

This topic will discuss the etiology and approach to poor weight gain in children older than two years in resource-abundant settings. Related issues are discussed in the following topic reviews:

●(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 "Dietary history and recommended dietary intake in children".)

Malnutrition in resource-limited settings is discussed in these topic reviews:

●(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, also known as weight faltering, can refer to either of the following patterns:

●Acute deceleration of weight gain – Weight loss (or sharp drop in weight percentile) in a child with a previously normal pattern of growth.

●Chronically subnormal weight gain – Weight curve that tracks well below the fifth percentile of standard weight-for-age growth curves (figure 1A-B) or a weight curve proportionate to, but substantially lower than, the child's height trajectory (figure 2A-B).

In either case, the definition of poor weight gain requires 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 on 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 — 

Factors contributing to poor weight gain 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 (table 1) [2]. When poor weight gain is related to an underlying medical condition, the gastrointestinal, cardiac, and renal systems are the most commonly involved (in decreasing order of frequency) [3].

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".)

Insufficient nutrient intake — The primary cause of poor weight gain in preschool and school-age children and adolescents is insufficient nutrient intake relative to typical metabolic and growth needs [4]. The etiology often is mixed; underlying medical conditions and environmental or psychosocial problems play a role [2,5].

Causes include:

●Food insecurity – Inadequate or inconsistent food supply.

●Behavioral contributors – A variety of behavioral factors can cause or contribute to insufficient nutrient intake:

•Feeding aversions – Toddlers may develop a feeding aversion because of problems with caregiver-child interactions where issues of control dominate; these dietary control issues are a common component of poor weight gain. Food aversion also can be a learned behavior related to sensations associated with food textures, consistencies, temperatures, or smells [6].

•Selective eating – Children between the ages of two and five years are often "picky" or "selective" eaters [7]. At this age, increased exploratory activities may limit the time a child focuses on eating. Unusual eating habits or a narrow range 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'.)

•Pediatric feeding disorder (PFD) – Very selective eating or disruptive behavior in the context of poor weight gain may be a marker for PFD. PFD is a broad category that describes children with impaired oral intake for their age with associated dysfunction (in psychosocial, medical, nutritional, or feeding skills domains) and without disturbances in perception of body weight or shape (table 2) [2]. PFD can be caused or exacerbated by problematic caregiver-child interactions, mental and behavioral health problems (in caregiver or child), developmental factors, or environmental factors (eg, distracting feeding environment). The diagnosis can also apply to children with medical problems that interfere with feeding, including motor impairments or conditions that impair the gastrointestinal, cardiorespiratory, and/or neurologic functions required for feeding.

Strategies for treating PFD depend on the contributing factors and may include nutritional, behavioral, and medical interventions, as outlined below. (See 'Management' below.)

•Avoidant/restrictive food intake disorder (ARFID) – ARFID is an eating or feeding disturbance seen primarily in older children [8,9]. It is characterized by avoidance or restriction of food intake that manifests with at least one of the following: clinically significant weight loss (or in children, poor growth or failure to achieve expected weight gain), clinically significant nutritional deficiency, reliance on enteral feeding or oral nutritional supplements for adequate intake, or substantial impairment of psychosocial functioning [10]. (See 'Indications for referral' below and "Eating disorders: Overview of epidemiology, clinical features, and diagnosis", section on 'Avoidant/restrictive food intake disorder'.)

•Disorders of gut-brain interaction – These are also known as functional gastrointestinal disorders and are common causes of abdominal symptoms in children. (See "Chronic abdominal pain in children and adolescents: Approach to the evaluation", section on 'Disorders of gut-brain interaction (functional abdominal pain disorders)'.)

•Other – 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 [11]. (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 foods or more nutritious solid foods [12]. (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, IBD), kidney, cardiac, or pulmonary conditions, may have anorexia, vomiting, early satiety, abdominal pain, constipation, or diarrhea [13].

•Medications, including some anticonvulsant drugs (eg, topiramate, felbamate, zonisamide) or stimulants for attention deficit hyperactivity disorder [14,15].

•Lactose intolerance, when chronically unrecognized and untreated, may lead to decreased appetite as a result of generally feeling unwell after consuming lactose, plus an attempt to avoid recurrent pain by eating less.

•Stressful psychosocial conditions can contribute to gastrointestinal symptoms (as part of a disorder of gut-brain interaction), which, in turn, can affect appetite.

●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 [16]. (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 [17-20]. Diets that avoid certain categories of food (eg, dairy free, vegetarian, low fat, low carbohydrate, or gluten free) may not supply all of the energy and nutrient needs for a growing child or adolescent [21,22]. (See "Vegetarian diets for children".)

●Pain or difficulty with eating:

•Discomfort or pain associated with eating (eg, in children with peptic disease, esophagitis, irritable bowel syndrome, dental caries, chronic constipation) [23-25]. (See "Gastroesophageal reflux disease in children and adolescents: Clinical manifestations and diagnosis".)

•Oromotor dysfunction – Problems with chewing and swallowing are common in children with central nervous system or neuromuscular disorders [26]. 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.

●Child neglect or maltreatment – These can interfere with growth due to withholding of food or affecting caregiver-child feeding interactions [27]. (See "Child neglect: Evaluation and management", section on 'Clinical presentations'.)

Increased nutrient requirements

●Increased metabolic rate – 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 [28-31].

•Congenital heart disease is associated with poor weight gain because of increased total daily energy expenditure in infants [28,29]. 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.

•Chronic lung disease (eg, bronchopulmonary dysplasia) is associated with increased energy needs during the early phases of disease, which may be mediated in part by physiologic stress (catecholamines and heart rate) [30]. If lung disease persists, toddlers and older children may have increased energy expenditure because of increased work of breathing and recurrent respiratory illnesses. (See "Bronchopulmonary dysplasia (BPD): Management and outcome", section on 'Growth and nutrition'.)

•Spasticity/hypertonicity, such as in children and adolescents with cerebral palsy or other neuromuscular causes of increased muscle tone, may be associated with increased energy expenditure. These individuals may also have feeding issues that contribute to poor weight gain [32]. (See "Cerebral palsy: Overview of management and prognosis", section on 'Growth and nutrition'.)

•Hyperthyroidism is associated with increased heart rate and blood pressure, but the mechanisms responsible for thyroid hormone-controlled energy expenditure have not been elucidated [33]. (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 [34,35]. (See "Evaluation of suspected obstructive sleep apnea in children", section on 'Examination'.)

•Diencephalic syndrome, a rare disorder associated with hypothalamic tumors, is characterized by severe emaciation but normal linear growth, increased appetite, and hyperactivity [36-38].

●Inflammation – Diseases that have an inflammatory or catabolic component, such as IBD, cystic fibrosis, 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 [39]. (See "Cystic fibrosis: Clinical manifestations and diagnosis" and "Growth failure and pubertal delay in children with inflammatory bowel disease".)

●Increased physical activity – Children and adolescents who engage in frequent vigorous physical activity have increased energy needs. In many cases, the child's growth is not affected, because of a compensatory increase in appetite. However, weight gain can be affected in children with extremely high energy expenditure (eg, long-distance running) or when combined with voluntary food restriction (eg, to meet weight class for wrestling) or insufficient food supply.

The fidgety, hyperactive, or "busy" child may expend more energy. However, whether this affects weight gain is uncertain [40]. Attention deficit hyperactivity disorder may be associated with increased weight gain or obesity, which may be related to shared risk factors rather than energy expenditure [41-43].

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

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

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

●Bulimia nervosa [11]. (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".)

●Pancreatic exocrine insufficiency (eg, due to cystic fibrosis, chronic pancreatitis, or Schwachman-Diamond syndrome). (See "Cystic fibrosis: Assessment and management of pancreatic insufficiency" and "Clinical manifestations and diagnosis of chronic and acute recurrent pancreatitis in children", section on 'Malabsorption' and "Shwachman-Diamond syndrome".)

●Chronic liver disease.

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

●Chronic kidney disease. (See "Chronic kidney disease in children: Complications".)

●Inborn errors of metabolism, including amino acid disorders, organic acidemias, urea cycle disorders, fatty acid oxidation disorders, and carbohydrate metabolism disorders. Symptoms and signs vary with the specific disorder but may include vomiting, hypoglycemia, and seizures. (See "Metabolic emergencies in suspected inborn errors of metabolism: Presentation, evaluation, and management", section on 'Gastrointestinal and feeding problems'.)

●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'.)

●Food protein sensitivity (allergy) that is not immunoglobulin (Ig) E-mediated, such as food protein-induced enterocolitis syndrome or food protein-induced enteropathy. This usually presents during infancy but, occasionally, is first diagnosed in older children. (See "Food protein-induced enterocolitis syndrome (FPIES)".)

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.

For children with typical growth rates, the energy stored in newly formed tissue is approximately 15 kcal/day, increasing to 30 kcal/day at peak growth velocity for adolescents [44]. Thus, energy deposition represents 1 to 2 percent of total energy requirements between early childhood and mid-adolescence [45]. For children undergoing catch-up growth after a period of undernutrition, catch-up weight gain of 20 g/kg/day requires approximately 85 kcal/kg/day above their normal energy requirements [46]. (See "Estimation of dietary energy requirements in children and adolescents", section on 'Energy cost of growth'.)

DIAGNOSTIC APPROACH

Overview — The conceptual framework for the diagnostic approach to poor weight gain depends on 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.

The usual sequence for evaluation and management of poor weight gain is to identify the major symptoms, consider the most common categories of disease possibilities, conduct a thorough physical examination, and screen for psychosocial contributors and possible medical problems. Then, when likely cause(s) are identified, the clinician initiates an empiric treatment regimen and monitors the clinical response [47,48]. 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 (table 3).

Present illness — Inadequate nutrient 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

●Poor gastrointestinal motility (eg, gastroparesis or generalized dysmotility), which can be postviral or part of an underlying neurologic disorder [49]; symptoms may include early satiety, excessive gastroesophageal reflux, and/or abdominal distension

●Medications that may affect appetite (eg, certain anticonvulsant drugs or stimulants for attention deficit hyperactivity disorder)

●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.

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 [50]. 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 (dietary recall) if caregivers are able to comply with the requirements for accurate recordkeeping. (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 [51-53]. 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 [54,55].

Past history

●Perinatal – A perinatal history may be useful for a young child, especially if poor weight gain or other symptoms began during infancy. It 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, method of feeding the child during the early postnatal period, and any clinical problems during the first postnatal year.

●Growth and developmental – Reviewing the growth curve with the parent or caregiver provides insight and facilitates targeted questions. Key points include:

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

•Was the child gaining normally and 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, financial challenges, parental divorce, child maltreatment, or substance use disorder)? These stressors may cause anxiety or depression in the child, which can affect appetite, or they may be markers for the parent/caregiver's ability to focus on feeding and nurturing the child.

-Did it coincide with other new symptoms or a new medical diagnosis that might explain the poor weight gain?

•Did the child acquire developmental milestones on schedule?

Social history — Many psychosocial issues such as poverty, young parental age, depression, alcohol or other substance use disorder, mental illness, and violence may contribute to food insecurity and, consequently, to poor weight gain in children. 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 if these statements are true [56]:

●"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 [56-59]. (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 [57]:

●2-1-1 – Telephone number that 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 for households without enough food

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

Family history — An assessment of familial growth patterns and the determination of midparental height may redirect concerns or provide reassurance. As an example, further evaluation is warranted if the child's actual height is two growth channels (percentile curves on a standard growth chart) below the expected midparental height (calculator 1). 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 3). 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 4), 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'.)

●Weight – 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).

●Height – Standing height is measured without shoes, 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). For accuracy, it is important to position the child so that their head, shoulders, buttocks, and heels are touching the vertical surface ("four-point stance").

●BMI – 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).

An alternative approach is to use 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 on current growth measurements and the pattern of growth failure. As examples:

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

●Decreased rates of growth in both weight and height are more likely due to prolonged undernutrition and/or an underlying medical condition.

●Serial height and weight measurements 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 are outlined in the table (table 4) and 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 gastrointestinal pathogen (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 [5]. 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 stepwise 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'.)

●Tissue transglutaminase-IgA (tTG-IgA) as a screen for celiac disease. Total serum IgA should also be measured on one occasion to exclude the possibility of false-negative results of tTG testing. (See "Diagnosis of celiac disease in children", section on 'Tissue transglutaminase antibodies'.)

●Urinalysis as a screen for protein or carbohydrate loss (eg, glucosuria in type 1 diabetes mellitus) and indolent kidney disease, such as renal tubular acidosis.

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:

●Blood tests:

•Tests to evaluate the kidneys (eg, renal tubular acidosis), liver, and pancreas:

-Electrolytes, blood urea nitrogen, creatinine, glucose, calcium, phosphorus, magnesium, albumin, total protein, liver enzymes, amylase, lipase.

These tests also provide an indication of nutritional status; they are commonly obtained by primary care clinicians for 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 (IBD). (See "Vegetarian diets for children", section on 'Vitamin B12' and "Vitamin and mineral deficiencies in inflammatory bowel disease", section on 'Vitamin B12'.)

-25-hydroxyvitamin D concentrations for those with risk factors for vitamin D deficiency (table 5). (See "Vitamin D insufficiency and deficiency in children and adolescents", section on 'Pathogenesis and risk factors'.)

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

●Stool tests:

•Routine culture, ova and parasite smears, and/or Giardia antigen if gastrointestinal infection is suspected (eg, bloody diarrhea, chronic diarrhea). (See "Giardiasis: Epidemiology, clinical manifestations, and diagnosis".)

•Fecal calprotectin if IBD or infectious colitis is suspected (eg, diarrhea, bloody stools). Elevated fecal calprotectin (>200 mcg/g) suggests IBD or other inflammatory colitis, whereas IBD is unlikely if calprotectin is clearly normal (<50 mcg/g). (See "Clinical presentation and diagnosis of inflammatory bowel disease in children", section on 'Stool tests'.)

•Reducing substances if malabsorption of carbohydrates is suspected, stool alpha-1 antitrypsin if protein-losing enteropathy is suspected, and elastase if pancreatic insufficiency is suspected. (See "Approach to the adult patient with suspected malabsorption".)

●Other tests:

•Abdominal ultrasound may be indicated when the physical examination is concerning for localized abdominal pain, hepatosplenomegaly, or masses.

•Immunologic testing for tuberculosis (via interferon-gamma release assay or 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:

●Endoscopy with biopsies may be indicated if certain alarm signs such as gastrointestinal bleeding, persistent vomiting, or anorexia are present. The goal of the endoscopy is to determine the cause of the symptoms, which include several gastrointestinal conditions in addition to Helicobacter pylori-related gastroduodenal disease. Noninvasive testing for H. pylori (eg, breath test, stool antigen, serum antibody tests) is generally not indicated for children with poor weight gain or short stature. (See "Helicobacter pylori: Diagnosis and management in the pediatric patient", section on 'Indications for testing in children'.)

Upper endoscopy is also generally indicated for children with positive serologic testing for celiac disease (tTG antibodies). Endoscopic biopsies can confirm a diagnosis of celiac disease and exclude other causes of the symptoms. (See "Diagnosis of celiac disease in children" and "Helicobacter pylori: Diagnosis and management in the pediatric patient", section on 'How to test'.)

●Further evaluation for IBD in children with concerning findings on the initial evaluation (diarrhea, elevated fecal calprotectin, hypoalbuminemia); the evaluation may include endoscopy and imaging. (See "Clinical presentation and diagnosis of inflammatory bowel disease in children".)

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

●Serologic testing for autoimmune disease; specific tests depend on the presenting symptoms, other laboratory test results, and suspected conditions. (See "Systemic juvenile idiopathic arthritis: Clinical manifestations and diagnosis" and "Childhood-onset systemic lupus erythematosus (cSLE): Clinical manifestations and diagnosis" and "Overview of autoimmune hepatitis".)

●Hepatitis (A, B, C) panel if liver aminotransferases are elevated. (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".)

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

●Cytomegalovirus and Epstein-Barr virus (IgM and IgG) if the child may be immunocompromised. (See "Overview of cytomegalovirus (CMV) 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 for growth hormone deficiency (starting with measuring insulin-like growth factor 1 and insulin-like growth factor-binding protein 3) [60]. (See "Diagnosis of growth hormone deficiency in children".)

●Sweat chloride test for children with any symptoms or signs suggesting cystic fibrosis (eg, respiratory symptoms, steatorrhea, any abnormal results of DNA testing, family history of cystic fibrosis). (See "Cystic fibrosis: Clinical manifestations and diagnosis".)

●Swallowing function study if swallowing dysfunction or aspiration is suspected (eg, in children with neurologic dysfunction).

●Advanced diagnostic imaging studies, such as:

•Gastric emptying scan (radionuclide) for children with suspected gastroparesis (eg, postprandial nausea or early satiety). (See "Approach to the infant or child with nausea and vomiting", section on 'Gastroparesis'.)

•Neuroimaging (eg, head computed tomography or magnetic resonance imaging) scans if there are concerns for an intracranial process (eg, prominent headache, nausea and vomiting, altered mental status). (See "Elevated intracranial pressure (ICP) in children: Clinical manifestations and diagnosis" and "Clinical manifestations and diagnosis of central nervous system tumors in children".)

MANAGEMENT — 

The management of poor weight gain in children older than two years of age depends on the clinical findings and results of diagnostic studies. The approach to treatment often is multifaceted [2]. 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 second percentile], weight for height <80 percent of the median, or body mass index [BMI] <12 kg/m²) [61,62]

●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 [5]. 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 [63]. Dietary interventions are based on increasing the intake of foods and beverages that have increased caloric density. Common strategies include:

●Increase caloric density – Add supplemental calories to foods by adding margarine, honey, syrups, gravies, creams, oils, cheese, peanut butter, avocados, and ice cream (table 6).

●Meal frequency – Offer the child two to three nutrient-rich snacks, in addition to three well-balanced meals daily.

●Drinks – When children drink too much, they may feel full and decrease the intake of solid foods. Encourage milk, but limit the total amount tailored to the child's age (generally 2 to 3 cups [480 to 720 mL] daily maximum). Avoid or minimize intake of sugary beverages including juice. Offering beverages at the end of meals or snacks may help the child focus on eating intake rather than filling up on less calorie-dense liquids.

●Supplements – If the child cannot eat enough nutrient-dense foods to gain weight adequately, commercially available nutrition supplements (formulas or "instant breakfast" product) may be used to supplement the child's intake. These supplements should not be offered near mealtime, since the goal is to add additional calories without suppressing the child's appetite for meals.

●Vitamins – For most children with poor weight gain, include a standard multivitamin supplement to ensure adequate micronutrient intake. For those with low intake of dairy products (or calcium-fortified plant "milk"), include a calcium supplement.

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 mealtimes enjoyable and avoid punishing the child or forcing them to finish portions of all foods offered. Families should be encouraged to eat meals together and model healthy eating behaviors. Tips for caregivers are outlined in the table (table 7).

Medication — For children ≥2 years and adolescents who do not have adequate catchup weight gain after three to six months of fortification of formula or food and behavioral guidance, we suggest a trial of cyproheptadine (a first-generation antihistamine). The dose is 0.25 mg/kg/day orally, divided twice daily. Cyproheptadine is discontinued if weight gain is not improved after two to three months or if there are significant side effects, such as drowsiness.

Limited data are available, and dosing regimens are varied. However, several randomized trials suggest that cyproheptadine often improves appetite and short-term weight gain in a variety of populations, including young children [64-68]. It is generally well tolerated; side effects may include drowsiness (common), paradoxical excitation (especially in young children), and hepatotoxicity (rare case reports).

Indications for referral — 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 [5]. 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. Other referrals should be tailored to the child's and family's needs and may include:

●Social work consultation for families to help address nonmedical drivers of health (eg, financial stressors, limited access to care, or other social challenges).

●Clinical therapist or child psychologist for management of behavioral problems, mental health concerns, and parenting support. In cases where there is concern for an eating disorder, referral to a mental health provider or adolescent specialist may be warranted.

●Occupational or speech therapy for children with oral motor or swallowing problems.

●Medical specialist for children with underlying medical problems that contribute to the poor weight gain.

In some institutions, a "feeding team" provides multidisciplinary support, including a dietitian, feeding therapist, and speech/swallowing therapy.

Follow up — Children with slow weight gain should be followed closely. The frequency of visits depends in part on the child's age, degree of underweight, and progress. In general, monthly follow-up visits are warranted until the child is making progress with nutritional and behavioral goals and weight gain, then less frequent visits until catch-up growth is complete.

Key elements of follow-up visits include:

●Anthropometrics – Measure weight and height, calculate BMI, and plot on appropriate-for-age, standard growth charts to assess progress.

●Nutrition – Review typical dietary intake, focusing on problems and goals identified during previous visits. (See 'Diet history' above.)

●Behavioral and psychosocial – Review any behavioral or psychosocial challenges identified during previous visits, and discuss solutions. Periodically inquire about any new challenges that may affect the child (eg, life changes, financial stressors). Offer referrals or other supports as needed. (See 'History' above.)

If the child increases their dietary intake sufficiently, catch-up weight gain should be accomplished in a three- to six-month timeframe.

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: Slow weight gain in babies and children (The Basics)")

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

SUMMARY AND RECOMMENDATIONS

●Definition – Poor weight gain refers to either:

•Acute weight loss or sharp drop in weight-for-age percentile in a child with previously normal pattern of growth, or

•Chronically subnormal weight gain, such that a child's weight for age tracks well below the fifth percentile (figure 1A-B) or a weight-for-age curve substantially lower than their height-for-age curve (figure 2A-B). (See 'Definition' above.)

●Etiology – The primary cause of poor weight gain in preschool and school-age children and adolescents is insufficient nutrient intake relative to typical metabolic and growth needs, which may be related to underlying medical, environmental, or social problems, alone or in combination (table 1). Other causes or contributors include increased nutrient requirements or nutrient losses (eg, due to underlying diseases). (See 'Etiology' above.)

●Diagnostic approach – The diagnostic approach typically involves performing a complete history (table 3) and physical examination (table 4) to identify the major symptoms and etiologic categories, followed by 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 growth pattern helps 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. Strategies for increasing a child's caloric intake are outlined in the tables (table 6 and table 7). If the child increases their dietary intake sufficiently, catch-up weight gain should be accomplished in a three- to six-month timeframe. (See 'Management' above.)

For children ≥2 years and adolescents who do not have adequate catchup weight gain after three to six months of fortification of formula or food, we suggest a trial of cyproheptadine (Grade 2C). Cyproheptadine should be discontinued if weight gain is not improved after two to three months or if there are significant side effects, such as drowsiness. (See 'Medication' above.)

ACKNOWLEDGMENT — 

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