Version July 2025
INTRODUCTION —
Poor weight gain refers to lack of appropriate weight gain for a child's age, length/height, sex, and genetic potential.
Chronic poor weight gain is often associated with impaired linear growth (stunting), and severe malnutrition can be complicated by secondary immune deficiency and impaired brain growth and development [1]. Early identification and expeditious treatment may help to prevent long-term developmental deficits [2]. (See "Poor weight gain in children younger than two years in resource-abundant settings: Management", section on 'Prognosis'.)
The etiology and initial evaluation of poor weight gain in children younger than two years in resource-abundant settings will be described here. Other UpToDate topics with related content are listed below.
●Resource-abundant settings:
•(See "Poor weight gain in children younger than two years in resource-abundant settings: Management".)
•(See "Poor weight gain in children older than two years in resource-abundant settings".)
●Resource-limited settings:
•(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".)
DEFINITIONS
Poor weight gain
●Terminology – Poor weight gain, also called weight faltering, describes children who do not gain weight as expected for their age, sex, and genetic potential. Weight that is disproportionately low for length/height is also known as wasting, which is a marker for acute malnutrition.
Broader terms that describe suboptimal gains in weight, length, and/or adiposity are "growth faltering" or "growth deficit." The term "failure to thrive" was commonly used in the past but is no longer preferred because it is ambiguous and "failure" can have negative connotations [3].
●Working definition – Consensus criteria for poor weight gain, including duration of concern about growth, are lacking [4]. Our working definition of poor weight gain is the combination of:
•Weight <2nd percentile – Determined by plotting on an appropriate growth chart after correction for gestational age (figure 1A-B) (calculator 1). Weight below the 2nd percentile is approximately equivalent to a Z-score of -2; the Z-score is a value that represents the number of standard deviations from the mean value (see "Measurement of growth in children", section on 'Use of Z-scores')
- and -
•Decreased velocity of weight gain – Interval weight gain that is less than expected for age (ie, the child's weight curve is flatter than the curves on the weight-for-age chart) (figure 2A-B) (calculator 2) [5]
Decreased velocity of weight gain is an important component of this definition. Children are growing normally if their weight is steadily increasing parallel to the standard weight curves even if their weight is <2nd percentile, especially if they have appropriate weight for length [6,7]. This growth pattern is more common among infants and young children with genetic short stature, constitutional growth delay, prematurity, or intrauterine growth restriction (figure 3) [3,8,9]. Nonetheless, such children warrant monitoring of growth. (See "Normal growth patterns in infants and prepubertal children", section on 'Variants of normal'.)
●Other definitions – Other indices of poor weight gain that are sometimes used include [1,5,10-12]:
•Weight below the 2nd percentile for gestation-corrected age and sex on more than one occasion (calculator 1); special growth charts for prematurity and selected genetic syndromes should be used when indicated (eg, for children with achondroplasia, Turner syndrome, etc). (See "Normal growth patterns in infants and prepubertal children", section on 'Growth charts for special populations' and "Growth and feeding issues in the neonatal intensive care unit graduate".)
•Weight <80 percent of ideal weight for age, using a standard growth chart (figure 4).
•Depressed weight for length (ie, weight age less than length age, weight for length <10th percentile (figure 2A-B) (calculator 2)).
•A rate of weight change that causes a decrease of two or more major percentile lines (figure 1A-B) (90th, 75th, 50th, 25th, 10th, and 5th) over time (eg, from 75th to 25th). (See "Normal growth patterns in infants and prepubertal children", section on 'Determinants of normal growth'.)
•A rate of daily weight gain less than that expected for age (table 1).
Degree of malnutrition — Any of the following metrics can be used for classifying the severity of wasting, indicating malnutrition (acute or acute-on-chronic malnutrition) (table 2) [13]:
●Weight-for-length Z-score – Derived from the World Health Organization (WHO) charts (girls, boys) or this calculator (calculator 2). Mild malnutrition = Z-score between -1 and -1.9, moderate malnutrition = Z-score between -2 and -2.9, and severe malnutrition = Z-score ≤-3.
●Mid-upper arm circumference (MUAC) – MUAC is determined with a tape measure (figure 5) and the Z-score derived from a WHO chart (girls, boys). Mild malnutrition = Z-score between -1 and -1.9, moderate malnutrition = Z-score between -2 and -2.9, and severe malnutrition = Z-score ≤-3. Alternatively, flat cutoffs can be used as a field measure, where moderate wasting corresponds to MUAC 11.5 to 12.4 cm and severe wasting MUAC <11.5 cm (for children 6 to 59 months) [14].
●Decline in weight-for-length Z-score (calculator 2) – Mild malnutrition ≥1, moderate malnutrition ≥2, and severe malnutrition ≥3 [13].
These measures can be applied in any setting but are particularly useful in resource-limited settings. (See "Malnutrition in children in resource-limited settings: Clinical assessment".)
EPIDEMIOLOGY —
Poor weight gain is common. In resource-abundant settings, it occurs in approximately 5 to 10 percent of children in primary care settings and 3 to 5 percent of those in the referral setting [15]. Among hospitalized children with known chronic medical problems, 20 to 40 percent are undernourished [16,17].
CAUSES AND RISK FACTORS —
Medical, nutritional, developmental/behavioral, and psychosocial factors may all contribute to poor weight gain (table 3) [12,18]. The causes and contributing factors vary by age of onset, with substantial overlap between age groups (table 4).
●Psychosocial risk factors include poverty, delayed introduction of complementary foods, social isolation, life stresses, poor parenting skills, disordered feeding techniques, caregiver substance use disorder or other psychopathology, certain health and nutrition beliefs (eg, fear of obesity or cardiovascular disease), exposure to violence, and child neglect or maltreatment [3,19]. In a primary care practice, one or more of these factors are present in most cases of poor weight gain [20]. Psychosocial contributors are also common among infants referred to specialty clinics.
●Virtually every organic disease process may contribute to poor weight gain. Key considerations in this age group include prematurity (particularly when associated with intrauterine growth restriction); developmental delay; congenital anomalies (eg, cleft lip and/or palate, genetic or chromosomal disorders); intrauterine exposures (eg, alcohol, anticonvulsants, infection); lead poisoning; anemia; and any medical condition that causes inadequate intake, increased metabolic rate, maldigestion, or malabsorption [3,19].
OVERVIEW
Goals and process — The goal of the evaluation of a child with poor weight gain is to identify the potential contributing factors (medical, nutritional, psychosocial, and developmental/behavioral) that can be addressed in the management [12,21].
●Clinicians involved – In many cases, the primary care clinician can initiate the evaluation and guide treatment. Additional health professionals (eg, dietitian, occupational or speech therapist, social worker, developmental and behavioral pediatrician, gastroenterologist, child psychologist) may facilitate information gathering and formulation of the management plan. Throughout the evaluation, it is important to work in partnership with and to support the caregivers, who may feel guilty about the child's poor weight gain. (See "Poor weight gain in children younger than two years in resource-abundant settings: Management", section on 'Adjunctive interventions'.)
●Process – The initial evaluation involves a thorough feeding history (table 5), medical history, and physical examination to assess for possible organic contributors to the poor weight gain (table 6 and table 7). (See 'History' below and 'Examination' below.)
For most children with poor weight gain, the initial evaluation also includes some basic laboratory tests. Additional laboratory testing and diagnostic imaging are guided by the findings from the initial evaluation and the degree of malnutrition. (See 'Diagnostic evaluation' below.)
Triage — All children with poor weight gain require evaluation to determine the cause and guide intervention. The most appropriate clinical setting and pace for the evaluation depend on the individual characteristics:
●Urgent – Urgent (same-day) full evaluation is appropriate for young infants (<6 months) with at least moderate malnutrition (table 2), older children with severe malnutrition, or those with acute weight loss. The full evaluation consists of a focused medical history, feeding history, physical examination, and basic laboratory evaluation, as outlined below. These steps can be accomplished in an extended visit in the outpatient setting or by referral for inpatient evaluation.
●Nonurgent – For other children, a staged evaluation may be more practical and appropriate. This approach consists of a basic screening evaluation on the first visit, focusing on the growth trajectory and severity of malnutrition; screening for serious psychosocial or medical problems; and conversation to establish a supportive therapeutic relationship with the caregivers and outline a plan. If there are no concerns for acute harm, the remainder of the staged evaluation can be accomplished during one or more follow-up visits, ideally within a few weeks of the initial visit, and should be directed by the findings on repeated history and physical examination.
EVALUATION
History — Important aspects of the history in a child with poor weight gain include detailed information regarding the age of onset, dietary intake and feeding practices, psychosocial factors, the child's environment, and the child's behavior and development.
Age of onset — Causes of poor weight gain can be loosely grouped according to the age of onset (table 4) [6,22-24].
Medical history — Important aspects of the medical history include [16]:
●Pre- and perinatal history – Low birth weight, intrauterine growth restriction, perinatal stress, and prematurity are important predisposing factors to poor weight gain. Prenatal exposures (eg, anticonvulsants, alcohol) may compromise growth and/or be risk factors for impaired caregiver-child interactions [3]. (See "Risks associated with epilepsy during pregnancy and the postpartum period", section on 'Effects of ASMs on the fetus and child' and "Fetal alcohol spectrum disorder: Clinical features and diagnosis", section on 'Clinical features'.)
●Past medical history and review of systems – Key elements are outlined in the table (table 6):
●Family history – Family history should include the height and weight of parents and siblings and history of developmental delay, constitutional delay of growth and puberty, and any illnesses that may contribute to slow growth.
Diet and feeding — Detailed information regarding nutritional intake and feeding should be obtained, as outlined in the table (table 5) [22,25,26]. Specific areas of inquiry include [22,27,28]:
●Gastrointestinal symptoms – Vomiting and diarrhea may increase nutrient losses. Rumination (voluntary regurgitation of stomach contents into the mouth for self-stimulation) has been linked to sensory and emotional deprivation in infants but also may occur in older individuals, particularly in those with neurologic impairment [29].
●Breastfeeding problems – For breastfed infants, review feeding patterns and inquire about challenges (eg, nipple pain, milk supply, obstacles to frequent feeding). (See "Breastfeeding: Parental education and support" and "Common problems of breastfeeding and weaning".)
●Feeding problems – Including picky eating, food refusal, inappropriate self-feeding for age, anorexia, and caregiver responses to the child's eating patterns.
●Food preferences – Avoidance of foods with certain textures may indicate underlying oral motor dysfunction or autism spectrum disorder (ASD); otherwise unexplained avoidance of specific foods may indicate food intolerance or allergy, for which the young child cannot verbalize symptoms (eg, nausea, abdominal discomfort) or ASD. (See "Clinical manifestations of food allergy: An overview", section on 'Anaphylaxis' and "Autism spectrum disorder in children and adolescents: Clinical features", section on 'Atypical responses to sensory stimuli'.)
●Dietary restrictions – Dietary restrictions related to perceived food allergies/intolerances or dietary beliefs and practices (eg, fear of cardiovascular disease, vegetarian diet). Any dietary restriction in a child with poor weight gain warrants further detailed evaluation (eg, by a dietitian). Some such diets (eg, vegetarian) can be healthy if they are well balanced and have adequate nutrient density. (See "Vegetarian diets for children".)
●Beverages – Excessive consumption of fruit juice or sweetened beverages can suppress appetite with low nutritional value. In addition, they can cause functional/osmotic diarrhea and may result in loss of nutrients due to fructose and/or sorbitol malabsorption [7].
●Physical problems with feeding or swallowing – Structural abnormalities of the face, oral cavity, or aerodigestive system or neuromuscular dysfunction can prevent adequate food intake and/or cause aspiration. Aspiration is often silent or has minimal symptoms (eg, blinking or eye watering, delayed swallow during feeding, noisy/wet upper airway sounds). (See "Neonatal oral feeding difficulties due to sucking and swallowing disorders" and "Aspiration due to swallowing dysfunction in children", section on 'Evaluation'.)
Any dietary history is inherently imprecise and should be interpreted with caution. The history may be particularly inaccurate in families with psychosocial challenges because caregiver guilt may result in inaccuracies in reporting. Accuracy may be somewhat better if structured, semiquantitative measures are used, such as a 24-hour food recall or three-day food record. These measures may be helpful for children with moderate to severe malnutrition. Feeding questionnaires may provide meaningful information about feeding difficulties in children [30,31]. (See "Dietary history and recommended dietary intake in children", section on 'Dietary history'.)
Psychosocial — The psychosocial history is an essential part of the evaluation because poor weight gain can be an indicator of serious social or psychological problems in the family [16]. Psychosocial stressors are the predominant cause of insufficient intake in children of all ages [32]. The material and emotional resources of the caregiver(s) may not be available for the care of the child for a variety of reasons (eg, poverty, depression, substance use disorders, family discord, maladaptive parenting style) [12,33-36]. Many caregivers of children with poor weight gain lack self-esteem; the health care provider should work to identify the strengths of the family that will encourage development of a nurturing environment, rather than focus blame.
The psychosocial history should include an assessment of the child's caregivers and other household members, employment status, financial state, degree of social isolation, and family stress. If there are multiple caregivers, it is important to determine whether they have similar or disparate views of the growing and eating problem [12]. The psychosocial history should also explore how the child's poor weight gain affects the caregivers and family (eg, guilt, stress, family conflict).
The psychosocial history should specifically address:
●Poverty and food insecurity – An attempt should be made to determine if adequate food is available in the home [12,37].
•Endorsement of one or both of the following statements identifies households at risk for food insecurity [37-40] (see "Screening tests in children and adolescents", section on 'Screening for poverty'):
-"Within the past 12 months, we worried if 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."
•In the United States, eligibility for the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) is a marker for poverty. Families experiencing food insecurity who are not enrolled in WIC may benefit from referral and encouragement to enroll.
●Parenting skills and nutrition knowledge – The feeding history described above typically provides some information about the caregivers' nutrition knowledge. If this raises concern, a more detailed assessment and/or referral to a dietitian is warranted. (See "Introducing solid foods and vitamin and mineral supplementation during infancy", section on 'What to feed and how to advance' and "Dietary recommendations for toddlers and preschool and school-age children", section on 'Dietary composition'.)
●Psychosocial stressors and access to resources – Evaluation of psychosocial stressors may include questions about the frequency of changes of home address and household composition and whether the caregiver feels safe at home. Caregivers initially may avoid mentioning psychosocial problems such as marital discord or spousal abuse; discussions of such issues should take place over the course of several visits and are crucial to addressing growth holistically [41]. These conversations should be conducted in a supportive and nonjudgemental manner, demonstrating concern and compassion. (See "Intimate partner violence: Childhood exposure".)
In addition to identifying psychosocial stressors, it is important to identify the family's strengths and access to resources that can be used in formulating a management plan [3]. The involvement of a social worker can be helpful in this regard.
●Parent/caregiver factors – For the primary caregiver(s), explore social and emotional factors that might affect the feeding relationship. This may include whether the pregnancy was planned or unplanned, maternal age, use of medications for illness, alcohol or substance use disorder, physical or mental illness (including history of feeding/eating disorder), postpartum depression, or inadequate breast milk production [36,42].
A caregiver's personal history of adverse childhood experiences, eating disorder, or food-related anxiety can affect the feeding relationship [43,44] but must be approached carefully. Such issues might be elicited with nonjudgemental open-ended questions such as "what were mealtimes like for you as a child?" and "have there been times when you had an unhealthy relationship with food such as dieting too much?"
Mothers who are under stress may use breastfeeding to comfort themselves as well as their infants [45]. In infants who are older than six months of age, this may result in high frequency of breastfeeding, with associated reduced consumption of complementary foods and poor weight gain.
●Child neglect – Child neglect is an uncommon cause of poor weight gain in children [21,46-48] but should be considered in children if there is any history of [49]:
•Intentional withholding of food from the child
•Strong beliefs in health and/or nutrition regimes that lead to undernutrition (eg macrobiotic diet, raw diet, popular fad diets that exclude any one or more particular food group)
•Resistance to recommended interventions despite a supportive and thorough multidisciplinary team approach
In such cases, as well as in those where there is evidence of associated physical or emotional abuse, a report should be made to Child Protective Services. (See "Child neglect: Evaluation and management", section on 'Notification of child protective services'.)
Examination — The goal of the physical examination of a child with poor weight gain is to identify signs of genetic disorders or medical conditions contributing to undernutrition, malnutrition (eg, vitamin deficiencies), and child abuse or neglect.
General examination — Important aspects of the examination are listed in the table (table 7) [3,5,16,50].
Measurement of growth — Accurate measurement of the child's weight, recumbent length (figure 6), and head circumference is essential. In the child younger than two years, the recumbent length, rather than the standing height, should be obtained. These measures, along with the child's weight for length, should be plotted on a standardized growth chart and monitored with repeated measures over time.
●Growth charts – The World Health Organization (WHO) growth standards should be used to assess the growth of children younger than two years, as recommended by the Centers for Disease Control and Prevention [51]:
•Percentile charts
-Males – WHO charts are available through these links (length for age and weight for age, head circumference for age and weight for length) and in the figures (figure 1A, 2A, 2C-D)
-Females – WHO charts are available through these links (length for age and weight for age, head circumference for age and weight for length) and in the figures (figure 1B, 2B, 2E-F)
•Z-score charts
-Males – Z-score charts are available through these links (weight-for-age, length-for-age, weight-for-length)
-Females – Z-score charts are available through these links (weight-for-age, length-for-age, weight-for-length)
Z-scores are used to classify the severity of malnutrition (table 2). (See 'Degree of malnutrition' above.)
Percentiles and Z-scores also can be obtained from these calculators: weight-for-age (calculator 1) and weight-for length (calculator 2).
The WHO growth standards are appropriate for children of all races and ethnicities. Some genetic disorders (eg, achondroplasia, Williams-Beuren syndrome) have special growth charts. (See "Achondroplasia" and "Normal growth patterns in infants and prepubertal children", section on 'Growth charts for special populations'.)
●Correcting for prematurity – When assessing the growth of children who were born prematurely, growth parameters should be corrected for gestational age (by subtracting the number of weeks the child was premature from their postnatal age at the time of evaluation) [52]. This correction is designed to adjust growth targets during the period of "catchup growth" experienced by many preterm infants. However, the rate and duration of catchup growth may vary depending on gestational age, birth weight, comorbidities, and other factors.
We generally follow the traditional approach of correcting for weight through 24 months of age, for stature through 40 months of age, and for head circumference through 18 months of age [12]. An alternative approach is suggested in the 2009 United Kingdom WHO growth charts, which suggest correction of all three parameters until age two years for children born before 32 weeks gestation and at least until age 12 months for children born between 32 and 36 weeks gestation [53]. (See "Growth and feeding issues in the neonatal intensive care unit graduate", section on 'Routine growth monitoring'.)
Growth trajectory and proportionality — If possible, the growth trajectory should be plotted from birth. The timing of changes in the slopes of the weight, length, or head circumference trajectories can help to identify potential contributors to poor weight gain (eg, initiation of complementary foods, onset of diarrhea, psychosocial stressor) [3]. (See 'Age of onset' above.)
Proportionality is assessed by determining the weight-for-length percentile (calculator 2) (figure 2A-B) or the median age for the child's weight (weight age), length (length age), and head circumference (head circumference age).
Growth trajectory and proportionality may provide clues to the etiology of diminished weight:
●Wasting – Decreased weight in proportion to length ("wasting") reflects inadequate nutritional intake. The characteristic sequence is normal growth parameters at birth with subsequent deceleration in weight, followed (weeks to months later) by deceleration in stature (referred to as "stunting") and, finally, deceleration in head circumference (figure 7). As stunting develops, the weight for length may return toward normal [22].
●Stunting – Decreased length with a proportionately low weight may be nutritional (if longstanding), genetic, or endocrine in origin [12,22]. Information from the family history, growth trajectory, and calculation of the mid-parental height may help to distinguish between these possibilities. (See "Causes of short stature" and "Diagnostic approach to children and adolescents with short stature".)
●Normal growth variants – Genetic short stature or constitutional growth delay are normal growth patterns. They are characterized by normal growth parameters at birth followed by simultaneous deceleration in length and weight before two years of age (figure 3). After two years, these children have low weight and height percentiles but normal or near-normal growth velocity (as indicated by growth parallel to the curves). These normal growth patterns can be difficult to distinguish from pathologic causes of slow growth, and, in many cases, the diagnosis is confirmed by serial monitoring over time. (See "Normal growth patterns in infants and prepubertal children", section on 'Variants of normal' and "Causes of short stature" and "Diagnostic approach to children and adolescents with short stature".)
●Decreased head circumference – When head circumference is impaired as much as (or more than) weight or length, intrauterine infection, teratogenic exposures, congenital syndromes, and other causes of microcephaly should be considered. (See "Microcephaly in infants and children: Etiology and evaluation", section on 'Etiology' and "Overview of TORCH infections", section on 'Clinical features of TORCH infections'.)
Deceleration of head circumference before deceleration in weight or length is suggestive of a neurologic disorder (eg, neonatal encephalopathy) [22]. (See "Microcephaly in infants and children: Etiology and evaluation", section on 'Monitoring head growth'.)
The growth trajectories of preterm and small for gestational age (SGA) infants are discussed separately. Premature and SGA infants have increased risk for subsequent undernutrition, but many infants with these conditions have catchup growth and subsequent normal growth velocity. (See "Growth and feeding issues in the neonatal intensive care unit graduate" and "Fetal growth restriction (FGR) and small for gestational age (SGA) newborns", section on 'Catch-up growth'.)
Caregiver-child interaction — During the examination, the clinician can observe the warmth, caring, and responsiveness of the caregiver to the child's cues, as well as the extent to which the child looks to the caregiver for comfort and support [3].
Observation of the child being fed may disclose a variety of factors relevant to insufficient intake [12,21,54]. Observation also may provide opportunities to provide positive reinforcement to the caregivers (eg, by pointing out how the child looks to the caregiver for comfort and support or how the caregiver appropriately responds to the child's cues). The observation session should be timed so that the child is hungry (typically at a regularly scheduled meal) and may occur in the office, hospital, or during a home visit by an experienced clinician. Another option is to ask the child's primary caregiver to video the child eating a meal; the video can then be reviewed with the family and advice offered based on the noted behaviors [19].
Important aspects of the feeding observation include [12,54]:
●Is the child adaptively positioned to eat (eg, in a high chair)?
●Is the feeding environment distracting (eg, the television is on in the background)?
●For bottle-fed infants, does the caregiver cuddle the infant or merely "prop" the bottle?
●Are the child's cues of hunger and satiety clear? Does the caregiver respond appropriately?
●Is there sufficient time for feeding?
●Is the child easily distracted during feeding?
●Does the child have oral motor or swallowing difficulties (eg, does the child have difficulty with foods of certain textures, and is feeding prolonged)?
●Does the caregiver permit age-appropriate autonomy (eg, self-feeding) and messiness?
●What is the tone of the feeding interaction for the child and for the caregiver (eg, pleasant, relaxed, stressful, hurried)?
●Is the child apathetic, irritable, noncompliant, or provocative?
●Is the caregiver irritable, punitive, depressed, disengaged, or intrusive?
Development and behavior — Children with poor weight gain should undergo formal developmental and behavioral testing for a number of reasons [12]:
●Developmental and behavioral problems may contribute to undernutrition. For example, it can be difficult to feed a child with a "difficult temperament." In addition, subtle neurologic deficits may interfere with the normal progression of feeding skills, limiting the child's ability to consume adequate nutrients (eg, fine motor deficits may affect the ability to self-feed) [1]. The feeding skills of a child with such deficits may be consistent with their developmental, rather than chronologic, age.
●Conversely, undernutrition may contribute to developmental and behavioral problems. For example, acute malnutrition may cause irritability. In addition, children with poor weight gain are at risk for long-term developmental and behavioral problems because insufficient intake of nutrients during the vulnerable periods of most rapid development may have a persistent effect on the nervous system [1]. Poor weight gain also appears to heighten developmental vulnerability to other adverse psychosocial factors that contribute to undernutrition (eg, poverty, maternal depression). The earlier these problems are identified, the sooner they can be addressed. (See "Developmental-behavioral surveillance and screening in primary care", section on 'Benefits of surveillance and screening'.)
Evaluation of the child's behavior can provide clues to an underlying problem. Children who fail to interact appropriately with their environment and caregivers (eg, avoidance of eye contact, absence of smiling or vocalization, lack of interest in the environment, lack of response to cuddling) may have developmental delay, hearing or vision impairment, ASD, or psychosocial or environmental deprivation. Behavioral rigidity or sensory aversions may result in self-imposed feeding restrictions. (See "Autism spectrum disorder in children and adolescents: Clinical features", section on 'Terminology'.)
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 [21,55,56]. However, selective screening studies may provide reassurance that certain conditions are unlikely to be present.
Initial tests — For most children <2 years with poor weight gain, we perform the following basic tests (table 8A):
●Complete blood count, tissue transglutaminase-immunoglobulin A antibody (tTG-IgA) with total IgA, C-reactive protein, and erythrocyte sedimentation rate (to screen for anemia, celiac disease, chronic infection, inflammation, and malignancy, respectively). Celiac disease testing is only relevant after gluten-containing foods have been introduced to an infant's diet.
●Urinalysis and culture as a screen for protein or carbohydrate loss (eg, glucosuria in type 1 diabetes mellitus) and indolent kidney disease, such as chronic urinary tract infection or renal tubular acidosis.
These routine tests may identify consequences of malnutrition (eg, anemia) or medical conditions that may contribute to undernutrition (eg, infection, kidney disease).
Additional tests — The following additional tests may be included in the initial evaluation if clinically indicated by the history or examination or if severe malnutrition is identified:
●Electrolytes, blood urea nitrogen, creatinine, glucose, calcium, phosphorus, magnesium, albumin, prealbumin, total protein, liver enzymes, amylase, and lipase to evaluate kidney, liver, or pancreatic disease; these tests also provide an indication of nutritional status. Serum ferritin (or an iron panel), vitamin B12, folate, and vitamin D levels may be indicated. (See "Laboratory and radiologic evaluation of nutritional status in children", section on 'Undernourished children'.)
●Stool studies, including guaiac, calprotectin, leukocytes, routine culture, ova and parasite smears, and/or Giardia antigen to evaluate gastrointestinal infection. (See "Giardiasis: Epidemiology, clinical manifestations, and diagnosis".)
●Chest radiograph to evaluate cardiac and pulmonary disease (eg, for children with exercise intolerance or respiratory symptoms).
Advanced tests — Specialized testing may be warranted if certain diagnoses are suspected or if an etiology has not been found and the child has not responded to dietary or behavior modification (table 8B). Specialized testing varies with the suspected disorder; examples include:
●Food allergy – 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".)
●Gastrointestinal disease
•Celiac disease – Initial screen with tTG-IgA and total serum IgA (if not already done), with follow-up testing as indicated. (See "Diagnosis of celiac disease in children", section on 'Tissue transglutaminase antibodies'.)
•Malabsorption – For infants and children with chronic diarrhea. (See "Approach to chronic diarrhea in neonates and young infants (<6 months)", section on 'Stool testing'.)
-Carbohydrates – Stool reducing substances (detects glucose, lactose, and fructose but not sucrose).
-Protein – Stool alpha-1 antitrypsin.
-Fat malabsorption – Stool elastase (detects pancreatic insufficiency but not other causes of fat malabsorption). Qualitative ("spot") fecal fat is a reasonable screen for malabsorption but has low accuracy.
•Inflammatory bowel disease:
-Stool studies including guaiac, leukocytes, and calprotectin. (See "Clinical presentation and diagnosis of inflammatory bowel disease in children", section on 'Stool tests'.)
-Upper gastrointestinal series with small bowel follow-through and advanced endoscopic studies. (See "Clinical presentation and diagnosis of inflammatory bowel disease in children".)
•Gastroesophageal reflux disease – Esophageal pH and impedance monitoring and advanced endoscopic studies. (See "Gastroesophageal reflux disease in children and adolescents: Clinical manifestations and diagnosis", section on 'Diagnostic approach' and "Gastroesophageal reflux in infants", section on 'Diagnostic tests for selected patients'.)
•Swallowing dysfunction or aspiration – Swallowing function study.
•Vomiting or anorexia related to an intraabdominal or intracranial process – Abdominal ultrasound, radionuclide scans for gastric and biliary tract emptying, and abdominal and head computed tomography scans.
●Cystic fibrosis – Sweat chloride test. (See "Cystic fibrosis: Clinical manifestations and diagnosis".)
●Inborn errors of metabolism or genetic syndromes – 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".)
●Endocrine disorders:
•Hyperthyroidism – Serum thyroid-stimulating hormone, free thyroxine, and triiodothyronine. (See "Clinical manifestations and diagnosis of Graves disease in children and adolescents".)
•Growth hormone deficiency – Insulin-like growth factor 1 and insulin-like growth factor-binding protein 3. (See "Diagnosis of growth hormone deficiency in children".)
●Infectious diseases:
•Human immunodeficiency virus (HIV) test if HIV infection is suspected. (See "Pediatric HIV infection: Diagnostic testing in children younger than 18 months" and "Screening and diagnostic testing for HIV infection in adults", section on 'Testing algorithm'.)
•Tuberculin skin testing or interferon-gamma release assay if tuberculosis is suspected. (See "Tuberculosis infection (latent tuberculosis) in children" and "Tuberculosis disease in children: Epidemiology, clinical manifestations, and diagnosis".)
•Cytomegalovirus and Epstein-Barr virus IgM and IgG. (See "Overview of cytomegalovirus (CMV) infections in children" and "Clinical manifestations and treatment of Epstein-Barr virus infection".)
•Hepatitis (A, B, and C) panel if hepatitis is suspected. (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".)
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 5th to 6th 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 10th to 12th 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
●Definitions
•Poor weight gain – A practical definition for poor weight gain is weight less than the 2nd percentile for gestation-corrected age and sex when plotted on an appropriate growth chart (figure 1A-B) (calculator 1) and decreased velocity of weight gain (figure 2A-B) (calculator 2). However, a consensus definition is lacking. (See 'Definitions' above.)
Infants and young children with genetic short stature, constitutional growth delay, prematurity, or intrauterine growth restriction who have appropriate weight for length and normal growth velocity may not have poor weight gain. (See 'Definitions' above.)
•Degree of malnutrition – Generally classified by weight-for-length or mid-upper arm circumference (MUAC) Z-scores (table 2). (See 'Degree of malnutrition' above.)
●Causes – Poor weight gain can be caused by inadequate intake, inadequate absorption, increased urinary or intestinal losses, increased requirements, or ineffective utilization (table 3). (See 'Causes and risk factors' above.)
●Goal of evaluation – The goal of the evaluation of a child with poor weight gain is to identify the potential contributing factors (medical, nutritional, psychosocial, and developmental/behavioral). Ancillary providers (eg, dietitian, occupational or speech therapist, social worker, developmental and behavioral pediatrician, gastroenterologist, child psychologist) can facilitate information gathering. (See 'Goals and process' above.)
●History – Important aspects of the history include the age of onset (table 4), symptoms suggesting an underlying medical condition (table 6), dietary intake and feeding practices (table 5), and psychosocial factors. (See 'History' above.)
●Physical examination – Important aspects of the physical examination include assessment for genetic disorders or medical conditions to undernutrition, malnutrition (eg, vitamin deficiencies), and child abuse or neglect (table 7); observation of caregiver-child interaction; and evaluation of behavior and development. (See 'Examination' above.)
Assessment of the growth trajectory and proportionality may provide clues to the etiology of diminished weight (see 'Growth trajectory and proportionality' above):
•Deceleration in weight before length – In children with inadequate nutritional intake, the typical growth pattern is normal growth parameters at birth with subsequent deceleration in weight, followed (weeks to months later) by deceleration in stature (referred to as "stunting") and, finally, deceleration in head circumference (figure 7).
•Proportional deceleration in weight and length – In children with genetic short stature or constitutional growth delay (which are normal variants of growth), the typical growth pattern is normal growth parameters at birth, followed by simultaneous and proportionate deceleration in length and weight (figure 3). Such children require no intervention but warrant monitoring to ensure that they continue to have a normal growth velocity (ie, growth parallel to the curve) after two years of age.
In other cases, proportionate decreases in length and weight may be related to nutritional (if longstanding), genetic, or endocrine factors. The family history, growth trajectory, and calculation of the mid-parental height may help to distinguish between these possibilities.
•Deceleration in head circumference – Head circumference is the last growth parameter to be affected by chronic malnutrition. When head circumference is affected as much or more than weight or length, other causes of microcephaly should be considered (intrauterine infection, teratogenic exposures, and congenital syndromes). (See "Microcephaly in infants and children: Etiology and evaluation", section on 'Monitoring head growth'.)
●Laboratory tests and imaging studies – Most children should have only a basic laboratory evaluation. Additional tests may be appropriate if clinically indicated by the history or examination or if severe malnutrition is identified (table 8A-B). (See 'Diagnostic evaluation' above.)
ACKNOWLEDGMENT —
The UpToDate editorial staff acknowledges Rebecca Kirkland, MD, MPH, and Kathleen J Motil, MD, PhD, who contributed to earlier versions of this topic review.
