Close attention to nutrition and growth is essential in caring for children with cystic fibrosis (CF). Growth and nutritional status should be monitored as part of routine CF care. Children with CF should achieve growth and nutritional status comparable with that of well-nourished children without CF. Children with CF are at risk for nutritional deficiencies. Optimal nutritional and growth status may be difficult to attain in this population given risk of insufficient caloric intake and likelihood of increased caloric expenditure. Various methods to attain optimal nutritional status may be used, including oral supplementation, behavioral treatment, pharmacotherapy, and enteral nutrition.
Key points
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Close monitoring of nutrition and growth is essential to the care of children with cystic fibrosis (CF). Growth and nutrition should be assessed at every visit to the CF care center.
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Body mass index (BMI) percentile is the most commonly used marker of nutritional status. Nutritional status is directly associated with pulmonary function.
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It is recommended that children with CF achieve growth and nutritional status comparable with that of well-nourished children without CF. Specifically, this means weight-for-length greater than the 50th percentile in children less than 2 years of age and BMI greater than the 50th percentile in children older than 2 years.
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Barriers to attaining and maintaining nutritional status include decreased caloric intake, gastrointestinal dysfunction, increased caloric expenditure, and psychosocial issues.
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Methods used to optimize nutritional status include intensive dietary and behavioral counseling, use of oral supplements, and enteral tube feedings.
Importance of adequate nutrition and growth
Close attention to nutrition and growth is integral to the care of patients with cystic fibrosis (CF). The Cystic Fibrosis Foundation (CFF) recommends that children with CF achieve nutritional status comparable with that of healthy children. Growth and nutritional status should be assessed at every visit. Despite multiple advances in the digestive care of patients with CF, appropriate nutritional status remains difficult to attain. In this article the authors discuss the assessment of growth and nutrition, nutritional goals and challenges, and optimization of nutritional status.
Dr Dorothy Andersen wrote the original reference to CF as a new entity in 1938. She described CF causing early death in infants because of extreme malnutrition. Autopsies revealed destruction of the pancreas, and eventually the role of maldigestion as a cause of malnutrition in CF was understood. Dr Harry Shwachman encouraged patients to follow a low-fat or fat-free diet to minimize the symptoms of steatorrhea, resulting in worsening malnutrition and a characteristic physical appearance including a swollen abdomen, lack of subcutaneous fat and muscle mass, and overall wasting. Later, comparisons of 2 large CF programs with differing approaches to dietary fat restriction showed that those on a high-fat diet had better growth and survival contributing to the current recommendations for a high-calorie, fat-unrestricted diet. Important advances in the nutritional management of patients with CF include the development of pancreatic enzyme replacement therapy, the availability of nutritional supplements, and the use of enteral tube feedings.
Body mass index (BMI) and BMI percentile for age are important measures of nutritional status in children with CF. It is recommended that height and weight be measured and BMI calculated by dividing the weight in kilograms by the height in meters squared at least every 3 months ( Table 1 ). The 2000 edition of the growth charts issued by the Centers for Disease Control and Prevention (CDC) should be used to compare each patient’s BMI percentile to age- and sex-matched norms. The goal is a weight-for-length at or greater than the 50th percentile in children less than 2 years of age and a BMI at or greater than the 50th percentile for children older than 2 years, meaning that nutritional status is comparable with that of well-nourished healthy children. The rationale for this goal is that an association exists between lung function, generally measured by forced expiratory volume in 1 second (FEV 1 ) percent predicted, and nutritional status ( Fig. 1 ).
| At Diagnosis | Every 3 mo Birth to 24 mo | Every 3 mo | Annually | |
|---|---|---|---|---|
| Head circumference | x a | x | — | — |
| Weight (to 0.1 kg) | x | x | x | — |
| Length (to 0.1 cm) | x | x | — | — |
| Height (to 0.1 cm) | x | — | x | — |
| Midarm circumference (to 0.1 cm) | x | — | — | x |
| TSF (to 1.0 mm) | x b | — | — | x |
| Midarm muscle area, mm 2 (calculated from MAC and TSF) | x b | — | — | x |
| Midarm fat area, mm 2 (calculated from MAC and TSF) | x b | — | — | x |
| Biological parents height c | x | — | — | — |
| Pubertal status, female | — | — | — | x d |
| Pubertal status, male | — | — | — | x e |
| 24-hour diet recall | — | — | — | x |
| Nutritional supplement intake f | — | — | — | x |
| Anticipatory dietary and feeding behavior guidance | — | x | x g | x |
a If less than 24 months of age at diagnosis.
b Only in patients more than 1 year of age.
c Record in centimeters and sex-specific height percentile; note patients’ target height percentile on all growth charts.
d Starting at 9 years of age, annual pubertal self-assessment form (patients or parent and patient) or physician examination for breast and pubic hair Tanner stage determination; annual question as to menarchal status. Record month and year of menarche on all growth charts.
e Starting at 10 years of age, annual pubertal self-assessment form (patients or parent and patient) or physician examination for genital development and pubic hair Tanner stage determination.
f A review of enzymes, vitamins, minerals, oral or enteral formulas, herbal, botanical, and other complementary and alternative medicine products.
g Routine surveillance may be done informally by other team members, but the annual assessment and every 3 monthly visits in the first 2 years of life and every 3 monthly visits for patients at nutritional risk should be done by the center dietician.
BMI is the most widely accepted measure of nutritional status in patients with CF. In the past, percentage of ideal body weight was often used; however, BMI is a more accurate measure of nutritional status. Even so, it is essential to remember that some children with short stature may have a BMI at or greater than the 50th percentile but still have suboptimal nutritional status. In fact, it is thought that height is related to lung volume; therefore, the importance of achieving adequate linear growth cannot be overstated.
The 2002 consensus report on nutrition for pediatric patients with CF notes that extra attention should be paid to nutrition and growth at 3 specific times: the first 12 months after diagnosis, the first 12 months of life for infants diagnosed prenatally or at birth, and the peripubertal growth period. The establishment of a pattern of normal growth (ie, similar to children without CF) during early childhood sets the stage for continued growth for the remainder of childhood and adolescence. As more and more patients are diagnosed prenatally or at birth (see section on newborn screening and diagnosis), increasing emphasis is being placed on the care of toddlers and preschoolers. New guidelines that pertain to all aspects of care in this age group are forthcoming and are discussed later. In addition, recent research based on data from the CF Patient Registry has shown the importance of early childhood nutrition for pulmonary health and overall outcomes later in life. One important study demonstrated that greater weight at 4 years of age is associated with greater height, better pulmonary function, fewer complications of CF, and better survival through 18 years of age.
Importance of adequate nutrition and growth
Close attention to nutrition and growth is integral to the care of patients with cystic fibrosis (CF). The Cystic Fibrosis Foundation (CFF) recommends that children with CF achieve nutritional status comparable with that of healthy children. Growth and nutritional status should be assessed at every visit. Despite multiple advances in the digestive care of patients with CF, appropriate nutritional status remains difficult to attain. In this article the authors discuss the assessment of growth and nutrition, nutritional goals and challenges, and optimization of nutritional status.
Dr Dorothy Andersen wrote the original reference to CF as a new entity in 1938. She described CF causing early death in infants because of extreme malnutrition. Autopsies revealed destruction of the pancreas, and eventually the role of maldigestion as a cause of malnutrition in CF was understood. Dr Harry Shwachman encouraged patients to follow a low-fat or fat-free diet to minimize the symptoms of steatorrhea, resulting in worsening malnutrition and a characteristic physical appearance including a swollen abdomen, lack of subcutaneous fat and muscle mass, and overall wasting. Later, comparisons of 2 large CF programs with differing approaches to dietary fat restriction showed that those on a high-fat diet had better growth and survival contributing to the current recommendations for a high-calorie, fat-unrestricted diet. Important advances in the nutritional management of patients with CF include the development of pancreatic enzyme replacement therapy, the availability of nutritional supplements, and the use of enteral tube feedings.
Body mass index (BMI) and BMI percentile for age are important measures of nutritional status in children with CF. It is recommended that height and weight be measured and BMI calculated by dividing the weight in kilograms by the height in meters squared at least every 3 months ( Table 1 ). The 2000 edition of the growth charts issued by the Centers for Disease Control and Prevention (CDC) should be used to compare each patient’s BMI percentile to age- and sex-matched norms. The goal is a weight-for-length at or greater than the 50th percentile in children less than 2 years of age and a BMI at or greater than the 50th percentile for children older than 2 years, meaning that nutritional status is comparable with that of well-nourished healthy children. The rationale for this goal is that an association exists between lung function, generally measured by forced expiratory volume in 1 second (FEV 1 ) percent predicted, and nutritional status ( Fig. 1 ).
| At Diagnosis | Every 3 mo Birth to 24 mo | Every 3 mo | Annually | |
|---|---|---|---|---|
| Head circumference | x a | x | — | — |
| Weight (to 0.1 kg) | x | x | x | — |
| Length (to 0.1 cm) | x | x | — | — |
| Height (to 0.1 cm) | x | — | x | — |
| Midarm circumference (to 0.1 cm) | x | — | — | x |
| TSF (to 1.0 mm) | x b | — | — | x |
| Midarm muscle area, mm 2 (calculated from MAC and TSF) | x b | — | — | x |
| Midarm fat area, mm 2 (calculated from MAC and TSF) | x b | — | — | x |
| Biological parents height c | x | — | — | — |
| Pubertal status, female | — | — | — | x d |
| Pubertal status, male | — | — | — | x e |
| 24-hour diet recall | — | — | — | x |
| Nutritional supplement intake f | — | — | — | x |
| Anticipatory dietary and feeding behavior guidance | — | x | x g | x |
a If less than 24 months of age at diagnosis.
b Only in patients more than 1 year of age.
c Record in centimeters and sex-specific height percentile; note patients’ target height percentile on all growth charts.
d Starting at 9 years of age, annual pubertal self-assessment form (patients or parent and patient) or physician examination for breast and pubic hair Tanner stage determination; annual question as to menarchal status. Record month and year of menarche on all growth charts.
e Starting at 10 years of age, annual pubertal self-assessment form (patients or parent and patient) or physician examination for genital development and pubic hair Tanner stage determination.
f A review of enzymes, vitamins, minerals, oral or enteral formulas, herbal, botanical, and other complementary and alternative medicine products.
g Routine surveillance may be done informally by other team members, but the annual assessment and every 3 monthly visits in the first 2 years of life and every 3 monthly visits for patients at nutritional risk should be done by the center dietician.
BMI is the most widely accepted measure of nutritional status in patients with CF. In the past, percentage of ideal body weight was often used; however, BMI is a more accurate measure of nutritional status. Even so, it is essential to remember that some children with short stature may have a BMI at or greater than the 50th percentile but still have suboptimal nutritional status. In fact, it is thought that height is related to lung volume; therefore, the importance of achieving adequate linear growth cannot be overstated.
The 2002 consensus report on nutrition for pediatric patients with CF notes that extra attention should be paid to nutrition and growth at 3 specific times: the first 12 months after diagnosis, the first 12 months of life for infants diagnosed prenatally or at birth, and the peripubertal growth period. The establishment of a pattern of normal growth (ie, similar to children without CF) during early childhood sets the stage for continued growth for the remainder of childhood and adolescence. As more and more patients are diagnosed prenatally or at birth (see section on newborn screening and diagnosis), increasing emphasis is being placed on the care of toddlers and preschoolers. New guidelines that pertain to all aspects of care in this age group are forthcoming and are discussed later. In addition, recent research based on data from the CF Patient Registry has shown the importance of early childhood nutrition for pulmonary health and overall outcomes later in life. One important study demonstrated that greater weight at 4 years of age is associated with greater height, better pulmonary function, fewer complications of CF, and better survival through 18 years of age.
Assessment of growth and nutritional status
The frequency at which growth parameters should be assessed is described in Table 1 . Growth is measured in children with CF by the same standards that are used for healthy children. For children less than 2 years of age, the World Health Organization’s growth standards are used to track weight, recumbent length, head circumference, and weight-for-length. For patients greater than 2 years of age, weight, height, and BMI are tracked using the CDC standard curves. Given the importance of height, growth velocity should be interpreted based on the child’s genetic potential for height. This velocity may be estimated using a variety of methods, including the midparental target height prediction.
In addition to anthropometrics, other components of the clinical evaluation may be used to assess nutritional status. Pubertal development is often delayed in patients with CF and can be due to poor nutrition (see section on endocrine disorders). Pubertal status may be assessed by patient or parent report or by physical examination with Tanner staging. Bone health may be evaluated by history, physical examination, laboratory, or radiologic studies (see section on endocrine disorders). Laboratory monitoring of nutritional status is discussed later ( Table 2 ).
| Nutrient | How Often to Monitor | |||
|---|---|---|---|---|
| At Diagnosis (Including At Newborn Screen) | Annually | Other | Test | |
| Beta carotene | — | — | At physician’s discretion | Serum levels |
| Vitamin A | x | x | — | Vitamin A (retinol) |
| Vitamin D | x | x | — | 25-OH vitamin D |
| Vitamin E | x | x | — | α-tocopherol |
| Vitamin K | x | — | Monitor in patients with hemoptysis, hematemesis, and/or liver disease | PIVKA-II (preferably) or prothrombin time |
| Essential fatty acids | — | — | Consider checking in infants or those with FTT | Triene/tetraene |
| Calcium/bone status | — | — | Age >8 y if risk factors are present a | Calcium, phosphorus, ionized PTH, DEXA scan |
| Iron | x | x | Consider in-depth evaluation for patients with poor appetite | Hemoglobin, hematocrit |
| Zinc | — | — | Consider 6-mo supplementation trial and follow growth b | — |
| Sodium | — | — |
| Serum sodium; spot urine sodium if total body sodium depletion suspected |
| Protein stores | x | x | Check in patients with nutritional failure or those at risk | Albumin |
a Risk factors for poor bone health include candidate for organ transplant, after transplantation, end-stage lung disease, bone fracture associated with low-impact activity, chronic steroid use, delayed pubertal development, nutritional failure.
b Particularly in infants not adequately growing despite adequate caloric intake and pancreatic enzyme replacement therapy.
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