Indications for nutritional assessment in childhood

INTRODUCTION — Pediatric malnutrition can present in three forms: undernutrition, overnutrition, and food insecurity ("hidden hunger"). The risk of malnutrition can be identified by the use of malnutrition screening tools [1]. When risk is identified, nutritional assessments determine the underlying causes and mechanisms and characterize the severity of malnutrition.

The goal of nutritional assessment in childhood is to prevent these nutritional disorders and the increased morbidity and mortality that accompany them. To meet this goal, pediatric clinicians must know the risk factors for obesity and protein energy malnutrition and must understand the normal and abnormal patterns of growth and the changes in body composition during childhood and adolescence. In addition, they must be able to accurately perform and interpret the results of the nutritional evaluation [2].

Nutritional assessment is the quantitative evaluation of nutritional status. A comprehensive nutritional assessment has five components:

●Dietary, medical, and medication history

●Physical examination

●Growth, anthropometric, and body composition measurements

●Laboratory tests

●Intervention and monitoring

The epidemiology of nutritional disorders and the indications for nutritional assessment are reviewed here. The dietary history and the clinical and laboratory features of nutritional disorders are discussed separately. (See "Dietary history and recommended dietary intake in children" and "Malnutrition in children in resource-limited settings: Clinical assessment" and "Measurement of growth in children" and "Measurement of body composition in children" and "Laboratory and radiologic evaluation of nutritional status in children".)

EPIDEMIOLOGY OF NUTRITIONAL DISORDERS

Prevalence — Obesity, acute or chronic malnutrition, and linear growth failure are the most common nutritional disorders in children.

●Obesity – In the United States, the prevalence of obesity in children 2 to 19 years has increased dramatically since the 1970s (figure 1) [3], and similar trends are seen in many other resource-abundant settings, although several high-income countries report plateauing or decreases in the trend. (See "Definition, epidemiology, and etiology of obesity in children and adolescents", section on 'Epidemiology'.)

●Undernutrition – Malnutrition (wasting) and linear growth failure (stunting) typically occur as a consequence of poor dietary intake, increased nutrient loss, and/or increased nutrient requirements in children with underlying disorders (table 1). (See "Dietary history and recommended dietary intake in children".)

•Poor intake can be a consequence of disease-induced anorexia, food aversion, dysfunctional parent-child interactions, or the presence of abdominal symptoms such as pain or nausea.

•Increased gastrointestinal losses can occur secondary to vomiting, diarrhea, malabsorption, or loss of the mucosal integrity of the gastrointestinal tract.

•Increased urinary nutrient loss is associated with some forms of renal disease and metabolic disorders.

•Increased nutrient requirements are associated with inflammatory, infectious, or metabolic complications of a variety of disease processes.

Effects of nutritional disorders on health — Acute malnutrition is associated with increased risk of illness and negative impact on the clinical outcome in children with other health disorders [4-7].

●In a large prospective study, malnourished Sudanese children were more likely to develop febrile illness with diarrhea or cough than were well-nourished children (1.75 to 2.0 times and 1.2 to 1.4 times more likely for diarrhea and cough, respectively) [4]. (See "Malnutrition in children in resource-limited settings: Clinical assessment", section on 'Pathophysiology'.)

●Studies of children undergoing orthotopic liver transplantation demonstrate improved one-month and one-year survival among those who were well-nourished at the time of the transplant compared with those who were undernourished (100 versus 23 percent and 88 versus 38 percent for one-month survival and one-year survival, respectively) [5]. Similar findings were reported in other studies [6,8,9].

Similarly, childhood obesity is associated with increased short-term morbidity (eg, hypertension, obstructive sleep apnea, insulin resistance, and slipped capital-femoral epiphyses) and is an independent risk factor for long-term morbidity and mortality in adulthood [10]. (See "Overview of the health consequences of obesity in children and adolescents".)

NORMAL PATTERNS OF GROWTH — The most rapid growth rates in healthy children occur during early infancy and adolescence (table 2) [11]. Alterations in height and weight velocity are the earliest predictors of poor nutritional status in children with chronic illness [12].

●Height velocity – Infants grow approximately 25 cm in length during the first year of life. This rate declines abruptly to 11 cm/year during the second and third years of life, then slows again to 6 cm/year in the preschool- and school-age child. For adolescent females, peak height velocity is typically 3 cm/six months but may be as high at 5 cm/six months. For adolescent males, peak height velocity is typically 4 cm/six months but may be as high as 6 cm/six months. (See "Normal growth patterns in infants and prepubertal children", section on 'Typical milestones' and "Normal puberty", section on 'Growth spurt'.)

●Weight velocity – Infants gain approximately 30 g/day between 0 and 3 months of age; 20 g/day between 3 and 6 months; and 10 g/day between 6 and 12 months. Subsequently, the rate of weight gain declines further, averaging 2.5 kg/year in the preschool- and school-age child. During the adolescent growth spurt, peak weight velocities average 3 kg/six months but may be as high as 6 kg/six months in girls and 7 kg/six months in boys. (See "Normal growth patterns in infants and prepubertal children", section on 'Typical milestones' and "Diagnostic approach to children and adolescents with short stature", section on 'Normal growth'.)

BODY COMPOSITION — The normal patterns of body composition are more difficult to characterize than are normal patterns of growth.

Measurement of body composition — Body composition can be estimated by calculating body mass index (BMI; or weight/height in children younger than two years), which is correlated with fat mass. Measurement of mid-upper arm circumference is a useful index of muscle mass and is widely used in low-resource settings. Fat mass can be measured more directly using techniques such as dual-energy x-ray absorptiometry (DXA); these techniques are useful in selected clinical situations. (See "Measurement of body composition in children", section on 'Measures of body composition'.)

Effect of malnutrition on body composition — Acute malnutrition is associated with loss of fat and muscle mass; the effect on body weight depends on whether there is associated nutritional edema (kwashiorkor). The effect of acute malnutrition on body composition differs in infants and older children. In the healthy infant, approximately 25 percent of body weight is fat, 15 percent protein, and 60 percent body water [13]. As the infant becomes malnourished, the absolute amount of body fat decreases and the proportion of body fat relative to body weight decreases markedly [14]. In addition, the absolute amount of body protein decreases, although the proportion of body protein relative to body weight remains unchanged. (See "Malnutrition in children in resource-limited settings: Clinical assessment".)

In contrast with acute malnutrition, malnutrition associated with chronic disease tends to have a greater effect on lean body mass than on body fat.

INDICATIONS FOR NUTRITIONAL ASSESSMENT — A nutritional assessment is warranted if a child meets established screening criteria for increased risk of developing malnutrition, growth failure, obesity, or food insecurity [1,15]. A complete nutritional assessment combines anthropometric data with other clinical information, including the presence or absence of an underlying illness or environmental or behavioral issues, whether any nutritional deficit is acute (<3 months) or chronic (>3 months), deviations in the longitudinal tracking of weight and height (eg, on a growth chart), potential mechanisms resulting in reduced nutrient intakes relative to nutrient requirements (eg, food deprivation, hypermetabolism, malabsorption), and the effects of nutrition on the child's functional status [16]. (See "Overview of enteral nutrition in infants and children", section on 'Nutritional assessment in children'.)

Recommended growth charts — General screening guidelines for nutritional risk are based upon growth curves that are standardized for the population being measured.

●Most children – In the United States, the Centers for Disease Control (CDC) recommends using the World Health Organization (WHO) curves for infants and children <2 years [17] and the CDC growth curves for children two years and older [11,18]. Outside of the United States, many countries use WHO curves until five years of age and the growth reference varies for older children. (See "Measurement of growth in children", section on 'Recommended growth charts with calculators' and 'Society guideline links' below.)

●Specific health conditions – Special growth charts are available for children with certain health conditions; the charts are available through the following links:

•Down syndrome growth charts

•Turner syndrome (figure 2)

•Cerebral palsy (see "Cerebral palsy: Evaluation and diagnosis", section on 'Nutrition and growth')

Thresholds for detailed assessment — The following growth patterns raise concerns for undernutrition. In general, deficits in weight gain or body mass index (BMI) raise concerns about acute malnutrition (wasting), while deficits in height or height velocity raise concerns about chronic malnutrition [19]. The use of Z-scores and/or decline in Z-scores of the following parameters is recommended to identify and document pediatric undernutrition [20].

●Indicators of wasting:

•Age <2 years – Weight-for-length <15^th percentile (or weight-for-length Z-score <-1).

•Age ≥2 years:

-BMI <15^th percentile (or BMI Z-score of <-1).

-BMI that has decreased across two or more major percentile curves on the growth chart (eg, BMI that decreases from the 30^th to the 7^th percentile) or a decline by ≥1 points in weight-for-length Z-score or BMI Z-score.

●Indicators of insufficient weight velocity:

•Prepubertal child – Weight gain <1 kg/year, or weight loss of ≥5 percent of usual body weight.

•During peak pubertal growth – Weight gain <1 kg/six months, or weight loss of ≥5 percent of usual body weight.

●Indicators of insufficient linear growth:

•Any age – Height-for-age <10^th percentile, or height Z-score of <-3.

•Age two years through mid-puberty – Height velocity <5 cm/year.

Note that a low weight-for-age but with normal weight-for-height or BMI percentiles is not usually caused by undernutrition, and such children should not be labeled as having weight faltering. The child may have short stature unrelated to nutritional issues. A clinical evaluation to determine the cause of short stature, which may include a nutritional component, is discussed separately. (See "Diagnostic approach to children and adolescents with short stature" and "Causes of short stature".)

●Indicators of excessive weight gain – The following growth patterns raise concerns for overweight or obesity in children between 2 and 18 years of age (table 3) (see "Definition, epidemiology, and etiology of obesity in children and adolescents", section on 'Definitions'):

•Overweight is defined as a BMI ≥85^th to <95^th percentile for age.

•Obesity is defined as a BMI ≥95^th percentile for age.

•Severe obesity is usually defined as a BMI ≥120 percent of the 95^th percentile for age (or a BMI ≥35 kg/m² if this is lower) (figure 3A-B) [21]. This corresponds to approximately ≥99^th percentile.

•A child whose BMI has increased by two or more major percentile curves is at risk for becoming overweight or obese (eg, BMI that increases from the 40^th to the 80^th percentile) [22].

A child whose parents have obesity also is at risk for developing obesity because of shared genetic and environmental influences. The clinician should monitor the child's growth and provide anticipatory guidance to encourage healthy eating and exercise patterns.

SPECIAL POPULATIONS — In addition to the above criteria, other children may be at risk for nutritional disorders because of hospitalization, medical conditions (eg, recurrent febrile illness or malignancy), dietary habits, feeding behavior, or activity levels. Nutritional assessment should be performed prospectively in these children to allow early intervention when a high-risk situation is identified.

Hospitalized children — Nutritional disorders are particularly common in hospitalized children.

●The prevalence of malnutrition was between 6.1 and 14 percent among children hospitalized children in the United States and Europe and 32 percent among those hospitalized in Turkey [23].

●In another study, 296 children admitted to a medical or surgical ward were studied prospectively [24]. During the inpatient stay (mean length seven days), weight loss occurred in 65 percent of patients and was greater than 2 percent of admission weight in 45 percent.

Acute malnutrition is most likely to occur in infants and toddlers or in adolescents, the age groups most frequently hospitalized [25]. Chronic malnutrition is more evenly distributed across all age groups. Adolescents are at greatest risk for obesity.

Children diagnosed with gastrointestinal disease, followed by renal or cardiac disease, are at greatest risk for chronic malnutrition [26] (see "Growth failure and pubertal delay in children with inflammatory bowel disease"). Children and adults who are hospitalized for severe burns have unusually high metabolic needs because of the hypermetabolic response to this type of injury. The nutritional assessment and management of these patients is discussed in detail in separate topic reviews. (See "Overview of nutrition support in burn patients".)

The more complex the patient's medical or surgical problem, the greater the likelihood the child is in need of nutritional assessment and intervention. Unfortunately, the complexity of the illness often correlates inversely with the amount of attention given to preventing nutritional depletion or excess early in the patient's course of illness. Tools to assist in the global nutritional assessment of hospitalized children are described separately. (See "Overview of enteral nutrition in infants and children", section on 'Global nutritional assessment'.)

Recurrent febrile illness — A febrile illness initiates a catabolic response that results in negative body nutrient balance because of the increased urinary loss of body proteins, minerals, and vitamins [27]. Negative nutrient balance persists until the febrile illness resolves. However, up to three weeks may be required to replenish the depleted body stores. Failure to pay attention to brief episodes of nutritional depletion can lead to a vicious cycle in which the nutritional status of the child worsens with each repeated illness and makes him or her more vulnerable to subsequent infections.

Malignancy — The prevalence of malnutrition among pediatric cancer patients varies widely. Malnutrition is present at diagnosis of cancer in more than 50 percent of children in resource-limited settings [28]. In resource-abundant settings, the prevalence of malnutrition ranges from less than 10 percent in children with acute lymphoblastic leukemia to 50 percent in children with advanced neuroblastoma [29,30]. Furthermore, nutritional status at diagnosis is a predictor of outcomes and quality of life [31,32]. Cancer treatment can contribute to malnutrition in the short term by inducing anorexia, mucositis, emesis, and/or diarrhea [33]. Serial measurements of height, weight, and food intake, as well as measurement of serum albumin and prealbumin, should be standard practice in the care of children with cancer [34,35].

Children with acute lymphoblastic leukemia are at risk for nutritional problems at diagnosis, during treatment, and in long-term follow-up. At diagnosis and during treatment, they tend to have low rates of undernutrition (typically less than 10 percent) [29,30]. However, they often gain weight excessively during and after therapy and have increased risk of obesity and short stature [36]. The mechanisms for this association have not been established but may include reduced habitual physical activity and effects of chemotherapy and/or cranial radiotherapy. (See "Acute lymphoblastic leukemia/lymphoblastic lymphoma: Outcomes and late effects of treatment in children and adolescents", section on 'Obesity'.)

Cancer treatment can have long-term effects on growth through a variety of mechanisms, including disruption of hypothalamic-pituitary function causing growth hormone deficiency and/or central hypothyroidism. (See "Endocrinopathies in cancer survivors and others exposed to cytotoxic therapies during childhood".)

Developmental disability — Children with motor and cognitive dysfunction are predisposed to feeding disorders. In one study, nutrition evaluation was performed in 79 children with moderate to severe motor or cognitive dysfunction who were referred for diagnosis and treatment of feeding or nutritional problems [37]. The primary diagnoses included cerebral palsy with intellectual disability, prematurity, chromosomal abnormality, central nervous system malformation, congenital infection, pervasive developmental delay, perinatal asphyxia, and fetal alcohol syndrome. The following findings were reported:

●Energy intake at the time of entry into the study, determined by dietary recall and three-day food records, was approximately 80 percent of the recommended daily allowance.

●Gastroesophageal reflux with or without aspiration was present in 44 of 79 patients, oropharyngeal dysphagia in 21, and aversive feeding behaviors in 14.

●After approximately two years of therapy based upon diagnosis (eg, medical treatment of gastroesophageal reflux, feeding therapy, gastrostomy tube placement), energy intake increased to 123 percent of the recommended daily allowance.

The assessment and management of nutritional problems in children with cerebral palsy are discussed in a separate topic review. (See "Cerebral palsy: Overview of management and prognosis", section on 'Growth and nutrition'.)

Paradoxically, there is also a high prevalence of obesity among some populations of children and adults with intellectual disability, particularly those with less severe disabilities and certain specific disorders such as Down syndrome [38-40]. The rates of obesity also vary depending on the country and the clinical setting in which the affected individual lives. In the United States, individuals living in smaller settings (families and group homes) have higher rates of obesity than those living in larger institutions [39]. Nutritional management of individuals with Down syndrome is discussed separately. (See "Down syndrome: Management", section on 'Obesity prevention'.)

Food insecurity — Food insecurity refers to reduced access to foods with sufficient variety or nutritional quality because of lack of money and other resources [41]. Families at risk for food insecurity can be screened for it by asking if the following statements describe their household [42]:

●"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."

Identifying children who live in households with food insecurity is important because they are at risk for nutritional disorders including obesity and are also likely to be sick more often, recover from illness more slowly, and be hospitalized more frequently. (See "Screening tests in children and adolescents", section on 'Screening for poverty'.)

The presence of multiple micronutrient deficiencies in the absence of an energy-deficit diet is often described as "hidden hunger." In particular, iron, zinc, iodine, and vitamin A deficiencies can occur in the absence of a deficit in energy intake as a result of consuming an energy-dense but micronutrient-poor diet [42,43]. (See "Micronutrient deficiencies associated with protein-energy malnutrition in children" and "Iron deficiency in infants and children <12 years: Screening, prevention, clinical manifestations, and diagnosis" and "Zinc deficiency and supplementation in children".)

Other — Additional children at risk for nutritional disorders are those who are [44]:

●Taking medications

●Anemic

●Allergic or intolerant to certain foods

●On a special diet or formula (prescribed or self-imposed)

●Receiving alternative or complementary therapies that include dietary modification (eg, a gluten-free diet), if done without guidance to ensure a balanced diet

●Using supplemental foods or vitamins

●Difficult to feed or have dental problems

●Not ambulatory

●Sedentary or overly active

●Tube fed (via gastrostomy, jejunostomy, or nasogastric tube)

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: Pediatric malnutrition" and "Society guideline links: Poor weight gain in infants and children".)

SUMMARY AND RECOMMENDATIONS

●Categories of nutritional disorders – Pediatric malnutrition can present in three forms: undernutrition, overnutrition, and food insecurity. Each of these conditions can have short- and long-term effects on growth, morbidity, and mortality. Identifying children with or at risk for nutritional problems is an important part of preventive medical care. (See 'Epidemiology of nutritional disorders' above.)

●Normal growth patterns – Serial measurements of weight and height are a valuable screen for nutritional problems when compared with expected growth rates for healthy children. The most rapid growth rates in healthy children occur during early infancy and adolescence (table 2). (See 'Normal patterns of growth' above.)

●Undernutrition – Acute malnutrition is associated with loss of fat and muscle mass; the effect on body composition differs in infants compared with older children. As the infant becomes malnourished, weight loss occurs, the absolute amount of body fat decreases, and the proportion of body fat relative to body weight decreases markedly. In the older child with chronic disease, the absolute amount of lean body mass generally is reduced to a much greater extent than body fat. (See 'Effect of malnutrition on body composition' above.)

The following growth patterns raise concerns for undernutrition. In general, deficits in weight gain or body mass index (BMI) raise concerns about acute malnutrition, while deficits in height or height velocity raise concerns about chronic malnutrition. However, a low weight-for-age but with normal weight-for-height or BMI percentiles is not usually caused by undernutrition. (See 'Thresholds for detailed assessment' above.)

•Indicators of wasting:

-Age <2 years – Weight-for-length <15^th percentile (or weight-for-length Z-score <-1).

-Age ≥2 years – BMI <15^th percentile (or BMI Z-score of <-1), or BMI that has decreased across two or more major percentile curves on the growth chart.

•Indicators of insufficient weight velocity:

-Prepubertal child – Weight gain <1 kg/year, or weight loss of ≥5 percent of usual body weight.

-During peak pubertal growth – Weight gain <1 kg/six months, or weight loss of ≥5 percent of usual body weight.

•Indicators of insufficient linear growth:

-Any age – Height-for-age <10^th percentile, or height Z-score of <-1.3.

-Age ≥2 years through mid-puberty – Height velocity <5 cm/year.

●Overnutrition – Nutritional assessment also is indicated for children who have overweight or obesity, those whose BMI percentile is increasing rapidly, and those whose parents have obesity (table 3). The clinician should monitor the child's growth and provide anticipatory guidance to encourage healthy eating and exercise patterns. (See 'Thresholds for detailed assessment' above.)

●Food insecurity – Food insecurity refers to reduced access to foods with sufficient variety or nutritional quality because of lack of money and other resources. Food insecurity is a risk factor for nutritional disorders including obesity and is also associated with other adverse health outcomes. (See 'Food insecurity' above.)

●Other indications for nutritional assessment – In addition to concerns raised by abnormal growth patterns or food insecurity, nutritional assessment is indicated in many hospitalized children and in children with chronic disorders, depending on the degree of disability and the clinical setting. (See 'Special populations' above.)