KDOQI Clinical Practice Guideline for Nutrition in Children with CKD: 2008 Update
2009; Elsevier BV; Volume: 53; Issue: 3 Linguagem: Inglês
10.1053/j.ajkd.2008.11.017
ISSN1523-6838
Autores Tópico(s)Clinical Nutrition and Gastroenterology
ResumoIntroductionRegular evaluation of nutritional status and provision of adequate nutrition are key components in the overall management of children with CKD. The traditional and predominant focus of nutritional management for children with impaired kidney function is to prevent the development of PEM and meet the patient's vitamin and mineral needs. More recently, overnutrition characterized by obesity and the long-term implications of unbalanced dietary and lifestyle practices are of increasing concern to the pediatric CKD population, and attention to this issue must be incorporated into the nutrition management scheme. Thus, the focus of nutritional care for children across the spectrum of CKD must always be centered on the achievement of the following goals:•Maintenance of an optimal nutritional status (ie, achievement of a normal pattern of growth and body composition by intake of appropriate amounts and types of nutrients).•Avoidance of uremic toxicity, metabolic abnormalities, and malnutrition.•Reduction of the risk of chronic morbidities and mortality in adulthood.This publication represents the first revision of the K/DOQI Pediatric Clinical Practice Guidelines for Nutrition in Chronic Renal Failure and is a completely revised and expanded document. The revision of the document published in 2000 was considered necessary for the following reasons:•To modify prior guideline statements based upon the availability of information published subsequent to the development of the 2000 guidelines.•To expand the target population with recommendations to address patients with CKD stages 2 to 5 and kidney transplant recipients, in addition to the dialysis population addressed in the prior publication.•To address a variety of topics not covered in the original guidelines, such as the dietary modification of sodium, potassium, fluid, calcium, and phosphorus, all of which can have a profound impact on patient outcomes.•To incorporate references to dietary recommendations, anthropometric reference values, and growth charts for the healthy population that replaced those on which the 2000 guidelines were based.•To reconcile discrepancies in recommendations for nutrient modification that exist between the pediatric nutrition guidelines and recent KDOQI guidelines on Hypertension and Dialysis Adequacy.One of the challenges for the Work Group in revising the 2000 K/DOQI Pediatric Nutrition Guidelines was the remarkable lack of published data available for the topic of nutrition in children with all stages of CKD. In addition, the quality of evidence in pediatric nephrology studies related to the issues addressed in these guidelines was frequently low due to small sample size, the lack of randomized controlled trials, and the lack of information for both short- and long-term clinical outcomes. Thus, the Work Group has generated a set of guideline recommendations to provide guidance to practitioners on the clinical aspects of nutrition management while at the same time recognizing the limited evidence that exists. These recommendations are based on available evidence, such as it exists; they also rely heavily on the opinion of the Work Group members and are graded accordingly. All submitted suggestions from physicians, nurses, and dietitians who participated in the public review of the draft recommendations were carefully reviewed and considered for incorporation into the recommendations by the Work Group Chairs and individual Work Group members. Most importantly, the absence of randomized controlled trials to support the recommendations made precludes the subsequent development of clinical performance measurements by oversight bodies on most, if not all, of the issues addressed by the guidelines.The process of revising the guidelines has also provided a unique opportunity to detect and highlight deficiencies in the scientific literature and to identify much needed areas of research for clinicians and scientists to undertake in the future. Areas of uncertainty arose for several reasons. For some issues, research in the pediatric CKD population has never been undertaken. For others, studies have provided indeterminate results, either because of small sample size or because infants, children, and adolescents were considered together, precluding the ability to relate outcomes to specific age groups. Studies that are rigorously designed to consider these issues and more and that address such topics as the role of inflammation on the nutritional status of children, the contribution of nutrition management to modification of cardiovascular risk, and the impact of frequent hemodialysis (HD) on energy, protein, and vitamin needs are required to ensure that future recommendations are truly evidence based.The charge to the Work Group was to develop comprehensive guideline recommendations that could provide valuable assistance to all clinicians (eg, dietitians, physicians, and nurses) involved in the nutritional management of children with CKD. We believe we have accomplished that goal. Of course, the primary use of these recommendations is to complement—but not replace—clinical judgment and to recognize that this is a “living document” that requires regular modification as new information becomes available. When used in this manner, we are confident that the information contained in this document will contribute to improved clinical management and outcomes of children with CKD.Finally, the Work Group expresses its appreciation to Michael Cheung, Dekeya Slaughter-Larkem, and Donna Fingerhut of the NKF-KDOQI Management Team and to Katrin Uhlig and Ethan Balk at the Tufts Center for Kidney Disease Guideline Development and Implementation for their guidance and assistance in the development of this guideline.RecommendationsRecommendation 1: Evaluation of Growth and Nutritional Status1.1The nutritional status and growth of all children with CKD stages 2 to 5 and 5D should be evaluated on a periodic basis. (A)1.2The following parameters of nutritional status and growth should be considered in combination for evaluation in children with CKD stages 2 to 5 and 5D. (B)iDietary intake (3-day diet record or three 24-hour dietary recalls)iiLength- or height-for-age percentile or standard deviation score (SDS)iiiLength or height velocity-for-age percentile or SDSivEstimated dry weight and weight-for-age percentile or SDSvBMI-for-height-age percentile or SDSviHead circumference-for-age percentile or SDS (≤3 years old only)viiNormalized protein catabolic rate (nPCR) in hemodialyzed adolescents with CKD stage 5D.1.3It is suggested that the frequency of monitoring nutritional and growth parameters in all children with CKD stages 2 to 5 and 5D be based on the child's age and stage of CKD (Table 1). (C) In general, it is suggested that assessments be performed at least twice as frequently as they would be performed in a healthy child of the same age. (C) Infants and children with polyuria, evidence of growth delay, decreasing or low BMI, comorbidities influencing growth or nutrient intake, or recent acute changes in medical status or dietary intake may warrant more frequent evaluation. (C)Table 1Recommended Parameters and Frequency of Nutritional Assessment for Children with CKD Stages 2 to 5 and 5DMeasureMinimum Interval (mo)Age 0 to 3 yCKD 2-3CKD 4-5CKD 5DCKD 2-3CKD 4-5CKD 5DCKD 2CKD 3CKD 4-5CKD 5DDietary intake0.5-30.5-30.5-21-31-31-36-1263-43-4Height or length-for-age percentile or SDS0.5-1.50.5-1.50.5-11-31-213-63-61-31-3Height or length velocity-for-age percentile or SDS0.5-20.5-20.5-11-61-31-26666Estimated dry weight and weight-for-age percentile or SDS0.5-1.50.5-1.50.25-11-31-20.5-13-63-61-31-3BMI-for-height-age percentile or SDS0.5-1.50.5-1.50.5-11-31-213-63-61-31-3Head circumference-for-age percentile or SDS0.5-1.50.5-1.50.5-11-31-21-2N/AN/AN/AN/AnPCRN/AN/AN/AN/AN/AN/AN/AN/AN/A1⁎Only applies to adolescents receiving HD.Abbreviation: N/A, not applicable. Only applies to adolescents receiving HD. Open table in a new tab Recommendation 2: Growth2.1Identification and treatment of existing nutritional deficiencies and metabolic abnormalities should be aggressively pursued in children with CKD stages 2 to 5 and 5D, short stature (height SDS < −1.88 or height-for-age < 3rd percentile), and potential for linear growth. (A)2.2Serum bicarbonate level should be corrected to at least the lower limit of normal (22 mmol/L) in children with CKD stages 2 to 5 and 5D. (B)2.3Recombinant human growth hormone (rhGH) therapy should be considered in children with CKD stages 2 to 5 and 5D, short stature (height SDS < −1.88 or height-for-age < 3rd percentile), and potential for linear growth if growth failure (height velocity-for-age SDS < −1.88 or height velocity-for-age < 3rd percentile) persists beyond 3 months despite treatment of nutritional deficiencies and metabolic abnormalities. (B)Recommendation 3: Nutritional Management and Counseling3.1Nutrition counseling, based on an individualized assessment and plan of care, should be considered for children with CKD stages 2 to 5 and 5D and their caregivers. (B)3.2Nutritional intervention that is individualized according to results of the nutritional assessment and with consideration of the child's age, development, food preferences, cultural beliefs, and psychosocial status should be considered for children with CKD stages 2 to 5 and 5D. (B)3.3Frequent reevaluation and modification of the nutrition plan of care is suggested for children with CKD stages 2 to 5 and 5D. (C) More frequent review is indicated for infants and children with advanced stages of CKD, relevant comorbidities influencing growth or nutrient intake, evidence of inadequate intake or malnutrition, or if acute illness or adverse events occur that may negatively impact on nutritional status. (C)3.4Nutritional management, coordinated by a dietitian who ideally has expertise in pediatric and renal nutrition, is suggested for children with CKD stages 2 to 5 and 5D. (C) It is suggested that nutritional management be a collaborative effort involving the child, caregiver, dietitian, and other members of the multidisciplinary pediatric nephrology team (ie, nurses, social workers, therapists, and nephrologists). (C)Recommendation 4: Energy Requirements and Therapy4.1Energy requirements for children with CKD stages 2 to 5 and 5D should be considered to be 100% of the EER for chronological age, individually adjusted for PAL and body size (ie, BMI). (B) Further adjustment to energy intake is suggested based upon the response in rate of weight gain or loss. (B)4.2Supplemental nutritional support should be considered when the usual intake of a child with CKD stages 2 to 5 or 5D fails to meet his or her energy requirements and the child is not achieving expected rates of weight gain and/or growth for age. (B)4.3Oral intake of an energy-dense diet and commercial nutritional supplements should be considered the preferred route for supplemental nutritional support for children with CKD stages 2 to 5 and 5D. (B) When energy requirements cannot be met with oral supplementation, tube feeding should be considered. (B)4.4A trial of intradialytic parenteral nutrition (IDPN) to augment inadequate nutritional intake is suggested for malnourished children (BMI-for-height-age < 5th percentile) receiving maintenance HD who are unable to meet their nutritional requirements through oral and tube feeding. (C)4.5A balance of calories from carbohydrate and unsaturated fats within the physiological ranges recommended as the AMDR of the DRI is suggested when prescribing oral, enteral, or parenteral energy supplementation to children with CKD stages 2 to 5 and 5D. (C)4.6Dietary and lifestyle changes are suggested to achieve weight control in overweight or obese children with CKD stages 2 to 5 and 5D. (C)Recommendation 5: Protein Requirements and Therapy5.1It is suggested to maintain dietary protein intake (DPI) at 100% to 140% of the DRI for ideal body weight in children with CKD stage 3 and at 100% to 120% of the DRI in children with CKD stages 4 to 5. (C)5.2In children with CKD stage 5D, it is suggested to maintain DPI at 100% of the DRI for ideal body weight plus an allowance for dialytic protein and amino acid losses. (C)5.3The use of protein supplements to augment inadequate oral and/or enteral protein intake should be considered when children with CKD stages 2 to 5 and 5D are unable to meet their protein requirements through food and fluids alone. (B)Recommendation 6: Vitamin and Trace Element Requirements and Therapy6.1The provision of dietary intake consisting of at least 100% of the DRI for thiamin (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), biotin (B8), cobalamin (B12), ascorbic acid (C), retinol (A), α-tocopherol (E), vitamin K, folic acid, copper, and zinc should be considered for children with CKD stages 2 to 5 and 5D. (B)6.2It is suggested that supplementation of vitamins and trace elements be provided to children with CKD stages 2 to 5 if dietary intake alone does not meet 100% of the DRI or if clinical evidence of a deficiency, possibly confirmed by low blood levels of the vitamin or trace element, is present. (C)6.3It is suggested that children with CKD stage 5D receive a water-soluble vitamin supplement. (C)Recommendation 7: Bone Mineral and Vitamin D Requirements and Therapy7.1Calcium7.1.1In children with CKD stages 2 to 5 and 5D, it is suggested that the total oral and/or enteral calcium intake from nutritional sources and phosphate binders be in the range of 100% to 200% of the DRI for calcium for age. (C)7.2Vitamin D7.2.1In children with CKD stages 2 to 5 and 5D, it is suggested that serum 25-hydroxyvitamin D levels be measured once per year. (C)7.2.2If the serum level of 25-hydroxyvitamin D is less than 30 ng/mL (75 nmol/L), supplementation with vitamin D2 (ergocalciferol) or vitamin D3 (cholecalciferol) is suggested. (C)7.2.3In the repletion phase, it is suggested that serum levels of corrected total calcium and phosphorus be measured at 1 month after initiation or change in dose of vitamin D and at least every 3 months thereafter. (C)7.2.4When patients are replete with vitamin D, it is suggested to supplement vitamin D continuously and to monitor serum levels of 25-hydroxyvitamin D yearly. (C)7.3Phosphorus7.3.1In children with CKD stages 3 to 5 and 5D, reducing dietary phosphorus intake to 100% of the DRI for age is suggested when the serum parathyroid hormone (PTH) concentration is above the target range for CKD stage and the serum phosphorus concentration is within the normal reference range for age. (C)7.3.2In children with CKD stages 3 to 5 and 5D, reducing dietary phosphorus intake to 80% of the DRI for age is suggested when the serum PTH level is above the target range for CKD stage and the serum phosphorus concentration exceeds the normal reference range for age. (C)7.3.3After initiation of dietary phosphorus restriction, it is suggested that serum phosphorus concentration be monitored at least every 3 months in children with CKD stages 3 to 4 and monthly in children with CKD stage 5 and 5D. (C) In all CKD stages, it is suggested to avoid serum phosphorus concentrations both above and below the normal reference range for age. (C)Recommendation 8: Fluid and Electrolyte Requirements and Therapy8.1Supplemental free water and sodium supplements should be considered for children with CKD stages 2 to 5 and 5D and polyuria to avoid chronic intravascular depletion and to promote optimal growth. (B)8.2Sodium supplements should be considered for all infants with CKD stage 5D on peritoneal dialysis (PD) therapy. (B)8.3Restriction of sodium intake should be considered for children with CKD stages 2 to 5 and 5D who have hypertension (systolic and/or diastolic blood pressure ≥ 95th percentile) or prehypertension (systolic and/or diastolic blood pressure ≥ 90th percentile and < 95th percentile). (B)8.4Fluid intake should be restricted in children with CKD stages 3 to 5 and 5D who are oligoanuric to prevent the complications of fluid overload. (A)8.5Potassium intake should be limited for children with CKD stages 2 to 5 and 5D who have or are at risk of hyperkalemia. (A)Recommendation 9: Carnitine9.1In the opinion of the Work Group, there is currently insufficient evidence to suggest a role for carnitine therapy in children with CKD stage 5D.Recommendation 10: Nutritional Management of Transplant Patients10.1Dietary assessment, diet modifications, and counseling are suggested for children with CKD stages 1 to 5T to meet nutritional requirements while minimizing the side effects of immunosuppressive medications. (C)10.2To manage posttransplantation weight gain, it is suggested that energy requirements of children with CKD stages 1 to 5T be considered equal to 100% of the EER for chronological age, adjusted for PAL and body size (ie, BMI). (C) Further adjustment to energy intake is suggested based upon the response in rate of weight gain or loss. (C)10.3A balance of calories from carbohydrate, protein, and unsaturated fats within the physiological ranges recommended by the AMDR of the DRI is suggested for children with CKD stages 1 to 5T to prevent or manage obesity, dyslipidemia, and corticosteroid-induced diabetes. (C)10.4For children with CKD stages 1 to 5T and hypertension or abnormal serum mineral or electrolyte concentrations associated with immunosuppressive drug therapy or impaired kidney function, dietary modification is suggested. (C)10.5Calcium and vitamin D intakes of at least 100% of the DRI are suggested for children with CKD stages 1 to 5T. (C) In children with CKD stages 1 to 5T, it is suggested that total oral and/or enteral calcium intake from nutritional sources and phosphate binders not exceed 200% of the DRI (see Recommendation 7.1). (C)10.6Water and drinks low in simple sugars are the suggested beverages for children with CKD stages 1 to 5T with high minimum total daily fluid intakes (except those who are underweight, ie, BMI-for-height-age < 5th percentile) to avoid excessive weight gain, promote dental health, and avoid exacerbating hyperglycemia. (C)10.7Attention to food hygiene/safety and avoidance of foods that carry a high risk of food poisoning or food-borne infection are suggested for immunosuppressed children with CKD stages 1 to 5T. (C)Recommendation 1: Evaluation of Growth and Nutritional StatusIntroductionNormal growth and development are major goals of pediatric CKD management. Because adequate nutritional status is important in achieving these goals, careful monitoring of nutritional status is essential. Nutritional status is a complex concept that cannot be adequately summarized by a single measurement. Multiple measures, considered collectively, are required to give a complete and accurate picture of nutritional status. Growth parameters are particularly important in children and should be accurately measured using calibrated equipment and standardized techniques (see Appendix 1).1.1The nutritional status and growth of all children with CKD stages 2 to 5 and 5D should be evaluated on a periodic basis. (A)1.2The following parameters of nutritional status and growth should be considered in combination for evaluation in children with CKD stages 2 to 5 and 5D. (B)iDietary intake (3-day diet record or three 24-hour dietary recalls)iiLength- or height-for-age percentile or standard deviation score (SDS)iiiLength or height velocity-for-age percentile or SDSivEstimated dry weight and weight-for-age percentile or SDSvBMI-for-height-age percentile or SDSviHead circumference-for-age percentile or SDS (≤3 years old only)viiNormalized protein catabolic rate (nPCR) in hemodialyzed adolescents with CKD stage 5D.1.3It is suggested that the frequency of monitoring nutritional and growth parameters in all children with CKD stages 2 to 5 and 5D be based on the child's age and stage of CKD (Table 1). (C) In general, it is suggested that assessments be performed at least twice as frequently as they would be performed in a healthy child of the same age. (C) Infants and children with polyuria, evidence of growth delay, decreasing or low BMI, comorbidities influencing growth or nutrient intake, or recent acute changes in medical status or dietary intake may warrant more frequent evaluation. (C)Rationale1.1: The nutritional status and growth of all children with CKD stages 2 to 5 and 5D should be evaluated on a periodic basis. (A)1.2: The following parameters of nutritional status and growth should be considered in combination for evaluation in children with CKD stages 2 to 5 and 5D. (B)Because of the high prevalence of growth retardation in children with CKD, nutrition has always been a primary focus of pediatric CKD care. Early studies emphasized the importance of adequate energy intake in maintaining normal growth in pediatric CKD. However, no study demonstrated a growth advantage to a caloric intake greater than about 75% of the RDA,2-4 which corresponds approximately to 100% of the EER in children older than 3 months. Interestingly, the prevalence of undernutrition in children with CKD is unknown. This is likely due, in part, to an inadequate definition of undernutrition in this population. In children with CKD, the prevalence of undernutrition has been demonstrated to vary widely—from 2% to 65%—depending on the definition used.5 In the general population, the World Health Organization (WHO) has defined undernutrition as weight-for-age, height-for-age, and weight-for-height 2 SDs or greater less than the Centers for Disease Control and Prevention (CDC) reference median,6 in recognition of the fact that long-term undernutrition may lead to wasting (low weight-for-height) and/or stunting (low height-for-age). However, this definition may be inappropriate in children with CKD. Whereas stunting can be reasonably attributed solely to long-term undernutrition in otherwise healthy children, the multifactorial cause of stunting in children with CKD makes it a poor choice as a definition of undernutrition in this group. In the CKD population, anthropometric definitions of undernutrition are complicated; consideration must be given to the appropriateness of measures for both age and height of the child.Body composition has yet to be well characterized in pediatric CKD. Few high-quality studies are available in which measures of body composition were adequately adjusted for height and appropriately compared with a healthy reference population.7-12 Of these, lean mass deficits were observed in some studies,11 but not others.7 Fat mass appears to be increased relative to height in children with CKD.11 Preliminary evidence in small numbers of children suggests that use of growth hormone may result in lower fat mass and higher lean mass for height.11Interpretation of many prior studies of nutrition and growth in pediatric CKD is difficult because most studies considered infants and older children together as a uniform group. There are reasons to believe that infants younger than 2 to 3 years behave very differently from older children. At a theoretical level, there are 2 main considerations. First, a much larger proportion of the daily energy requirement is devoted to growth in infants compared with older children. Second, growth is driven primarily by nutrition during infancy, whereas growth hormone and sex hormones have a dominant influence during childhood and adolescence, respectively.13-16 On a practical level, there is evidence to support the notion that infants and older children behave differently. Inadequate spontaneous calorie intake has been clearly demonstrated in infants with CKD17-19; energy intakes for older children usually are normal relative to body size.9 In studies separating children by age, weight-for-height indices, and BMI-for-age, z scores were low in younger children, but normal in older children.10,12 Lean mass deficits were also more likely in younger than older children.7,8,10 Routine calorie and/or protein supplementation have been shown to improve growth in infants with CKD.17-19 However, there is no clear evidence that routine nutritional supplements have a similar effect in older children.Because of these differences between infants and older children, the present recommendations emphasize the importance of considering the age of the child when planning nutritional monitoring and interventions.Historically, the main focus of malnutrition in children with CKD has been undernutrition; there is some evidence that obesity is beginning to be a problem in the CKD population.20-22Dietary IntakeIt is suggested that dietary intake be assessed regularly by a skilled registered dietitian by means of a 3-day diet diary. Three 24-hour recalls may be preferable in adolescents. Dietary intake data provide useful information about the quantity and quality of nutrients ingested. The 2 most practical and clinically feasible ways to determine usual daily intake are the prospective 3-day dietary diary and the retrospective 24-hour dietary recall. From either of these, daily intake of calories, macronutrients (carbohydrate, protein, and fat), vitamins, and minerals can be estimated. Each of the methods has its own limitations. Dietary diaries have been shown to give unbiased estimates of energy intake in normal-weight children younger than 10 years; however, underreporting is common in adolescents.23,24 Twenty-four–hour recalls may be better suited to adolescents. The most important limitation of the 24-hour recall method is its poor ability to capture the day-to-day variability in dietary intake. Children may be even more susceptible to this limitation than adults because they tend to have more day-to-day variability.25 It may be useful to obtain three 24-hour recalls to more completely evaluate the food-intake pattern. One weekend day should be included in a 3-day diet diary and as 1 of three 24-hour recalls. Despite their limitations, dietary recall interviews conducted by a skilled pediatric registered dietitian or dietary diaries completed by the patient and/or parent as instructed by a registered dietitian provide useful general information about the pattern of food intake. Information about dietary intake allows the treating team to evaluate the adequacy of a patient's intake before significant adverse changes in body composition result.Poor intake is expected in infants with CKD and should prompt immediate initiation of nutritional supplements if there is any evidence of inadequate weight gain or growth. When spontaneous intake is low in a poorly growing older child, consideration also must be given to the possibility that the poor intake is a result of the poor growth, rather than the cause. Spontaneous calorie intake increased by almost 12% in a study of 33 children with CKD during treatment with rhGH.26Length- or Height-for-Age Percentile or SDSLength (infants < 2 years) or height (children > 2 years) should be measured regularly, plotted on the length- or height-for-age curves, and the percentile and/or SDS should be calculated (Appendix 2, Table 32). Growth retardation is common in CKD.2,3,12,27,28 The impact of CKD on growth depends on both the degree of kidney impairment and age of the child. Normal growth can be divided into 3 phases: infancy (dominated by nutrition), childhood (dominated by growth hormone), and puberty (dominated by sex hormones).13 The infancy phase normally is replaced by the childhood pattern between 6 and 12 months of age. In CKD, onset of the childhood phase frequently is delayed until 2 to 3 years of age or interrupted by a transient resumption of the infancy pattern.13 CKD also results in a delay in the onset of pubertal growth, as well as a shorter pubertal growth spurt.29 Together, these alterations to the normal pattern of growth may lead to severe short stature. The typical CKD growth pattern is characterized by decreased growth velocity during infancy, followed by normal growth velocity during childhood and impaired growth velocity again during adolescence.16 However, growth velocity also may be low during the childhood phase in children with CKD stages 4 or 5.3,30 Numerous factors may influence growth in CKD, including acidosis,31 disturbances in the growth hormone axis,32 and poor nutritional intake.2 Nutritional intake has its greatest influence during the infancy phase of growth.16Length (infants) should be measured by using a length board, and height (older children), by using a wall-mounted stadiometer, preferably by the same well-trained person at each assessment. Calculating the SDS or plotting the child's height on the normal growth chart to determine the percentile allows comparison with healthy children. In 2000, the CDC published revised North American growth reference charts for infants and children up to 20 years of age (Figure 11, Figure 12, Figure 13, Figure 14).33 In 2006, the WHO released new growth standards for children from birth to 5 years of age (Figure 1, Figure 2, Figure 3, Figure 4, Figure 5, Figure 6, Figure 7, Figure 8, Figure 9, Figure 10).34 These growth standards are distinguished from the CDC reference charts in 2 important ways. First, the children contributing to the WHO Growth Standards were specifically selected to represent children growing under ideal conditions: they had nonsmoking mothers, were from areas of high socioeconomic status, and received regular pediatric health care, including immunizations. A subset of 882 infants, all breastfed for at least 4 months, provided longitudinal data for 24 months. Second, the study population was of broad ethnic diversity; participants were recruited from Brazil, Ghana, India, Norway, Oman, and the United States. Importantly, ethnicity had very little impact on growth, indicating that the growth standards reflect a reasonable expectation for gro
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