Contents
Contributors
Foreword
Preface
Acknowledgement
Part 1 Principles of Paediatric Dietetics
1 Nutritional Assessment, Dietary Requirements, Feed Supplementation
Introduction
Dietary principles
Dietary intake
Anthropometry
Growth charts
Evaluation of anthropometric measurements
Clinical assessment
Biochemistry and haematology
Other tests
Low birthweight and preterm infants
Infants over 2.5 kg birthweight
Fluid requirements in the first few weeks
Fluid requirements in older infants and children
Concentrating infant formulas
Nutrient-dense ready-to-feed formulas
Energy and protein modules
References
Further reading
Useful address
2 Provision of Nutrition in a Hospital Setting
Introduction
Infant and enteral feeds
Designated feed-making area
Structural design of feed-making areas
Staffing
Feed preparation
Delivery
Cleaning procedures
Microbiological surveillance
Procedures and documentation
Normal diet in a hospital setting
Modified diet in a hospital setting
Immunosuppression and ‘clean’ meal provision
Purchasing
Storage
Preparation
References
Part 2 Nutrition Support and Intensive Care
3 Enteral Nutrition
Choice of feeds
Feed thickeners
Routes of administration
Continuous versus bolus feeding
Enteral feeding equipment
Home enteral feeding
Feed administration and tolerance
Monitoring children on enteral feeds
References
Support group
Useful address
4 Parenteral Nutrition
Introduction
Nutrition support teams
Indications for parenteral nutrition in children
Considerations in paediatric parenteral nutrition
Nutrient requirements and solutions
Administration of parenteral nutrition
Delivery methods
Equipment
Weaning off parenteral nutrition
References
5 Nutrition in Critically III Children
Introduction
Assessment of nutritional status
Energy expenditure and substrate utilisation
Nutritional requirements
Early implementation of enteral nutrition
Routes and methods of enteral feeding on PICU
Immunonutrition
Probiotics
References
Part 3 Clinical Dietetics
6 Preterm Infants
Definitions
Nutritional requirements
Conditionally essential nutrients
Parenteral nutrition
Enteral nutrition
Feeding issues in special conditions
Post-discharge nutrition
Weaning onto solids
References
Further reading
Useful addresses
7 Gastroenterology
Introduction
Nutritional requirements
Fluid and dietary therapy of acute diarrhoea
Congenital chloride losing diarrhoea
Food allergy in gastroenterology
Coeliac disease
Carbohydrate intolerances
Fat malabsorption
Neonatal enteropathies and protracted diarrhoea
Modular feeds for use in intractable diarrhoea or short gut syndrome
Inflammatory bowel disease
Disorders of altered gut motility
References
Resource
Useful addresses
8 Surgery in the Gastrointestinal Tract
Introduction
Oesophageal atresia and tracheoesophageal fistula
Duodenal atresia
Hirschsprung’s disease
Exomphalos and gastroschisis
Short Bowel Syndrome
References
Useful addresses
9 The Liver and Pancreas
The liver
The pancreas
References
Useful address
10 Diabetes Mellitus
Introduction
The eating plan for a child with diabetes
Recommendations
Recommending an eating plan
Diet throughout childhood
Non-type 1 diabetes
Type 2 diabetes
Acknowledgement
References
Useful address
11 Cystic Fibrosis
Introduction
Clinical features
Diagnosis
Nutritional management
Nutritional support
Vitamin and mineral supplements
Essential fatty acid deficiency
Infant feeding in cystic fibrosis
Toddlers and behavioural feeding problems
Pancreatic enzyme replacement therapy
Dietary management of diabetes in children with CF
References
Useful address
12 The Kidney
Introduction
Acute renal failure
Chronic renal failure
Diet following renal transplantation
Nephrotic syndrome
Congenital nephrotic syndrome
Nephrogenic diabetes insipidus
Renal stones
Hypercalcaemia
Renal tubular disorders
References
13 The Cardiothoracic System
Congenital heart disease
Chylothorax
Glossary
Acknowledgements
References
Further reading
14 Food Hypersensitivity
Introduction
Important factors concerning food hypersensitivity reactions
Tests for diagnosis of food hypersensitivity
Natural history of food allergy
Dietary manipulation for food hypersensitivities
Dietary management of food hypersensitivities
Specific issues
Discussion of specific symptoms
Novel approaches in food hypersensitivity
Problems with dietary treatment in food hypersensitivity
Acknowledgements
References
Useful addresses
15 Immunodeficiency Syndromes
Introduction
B lymphocyte defects
T lymhphocyte defects
Defects in phagocytes
Defects of T and B lymphocytes
Bone marrow transplantation
HIV and AIDS
UK incidence and prevalence
Breast feeding and HIV transmission
Social problems
Diagnosis
Disease progression
Nutritional considerations
References
Useful addresses
16 Ketogenic Diets
Introduction
Efficacy
Mode of action
Indications and contraindications
Implementation
Calculating the diet
Meal distribution
Free foods
Recipes
Vitamins and minerals
Fluid requirements
Initiating the diet
Fine tuning the diet
Management of illness
Which ketogenic diet?
Enteral feeds
Monitoring the diet
Adverse effects
Duration and discontinuation of the diet
KetoPAG
References
17 Disorders of Amino Acid Metabolism, Organic Acidaemias and Urea Cycle Defects
History
Classification of PKU
Prevalence
Biochemistry
Genetics
Diagnosis
Clinical outcome
Non-dietary treatments
Dietary treatment
Monitoring the diet
Feeding different age groups with PKU
Maple Syrup Urine Disease
Tyrosinaemias
Tyrosinaemia type II: Richner-Hanhart syndrome
Homocystinuria
Pyridoxine responsive HCU
Pyridoxine non-responsive HCU
Treatment aims and biochemical monitoring
Dietary management of classical HCU
Management of the early diagnosed infant and child with HCU
Dietary management in later diagnosed cases
Organic Acidaemias and Urea Cycle Disorders
Disorders of propionate metabolism
Isovaleric acidaemia
Glutaric aciduria type 1
Urea cycle disorders
Arginase deficiency
Emergency Regimens
Acknowledgement
Appendix 17.1
References
Useful addresses
18 Disorders of Carbohydrate Metabolism
Glycogen storage disease type I
Galactosaemia
Galactokinase deficiency
UPD-galactose 4-epimerase deficiency
Hereditary fructose intolerance
Fructose-1,6-bisphosphatase deficiency
Acknowledgement
References
Useful addresses
19 Disorders of Fatty Acid Oxidation and Ketogenesis
Introduction
Medium chain acyl-CoA dehydrogenase deficiency
Long chain fatty acid oxidation disorders
Multiple acyl-CoA dehydrogenase deficiency
3-Hydroxy-3-methyIgIutaryI-CoA synthase deficiency
3-Hydroxy-3-methylglutaryl-CoA Iyase deficiency
AcknowIedgement
References
20 Lipid Disorders
Introduction
Hypolipoproteinaemias
Hyperlipoproteinaemias
References
Useful address
21 Peroxisomal Disorders
Peroxisomal disorders
Adult Refsum’s disease
Peroxisomal biogenesis disorders
Dietary treatment of adult Refsum’s disease
Dietary treatment of infantile Refsum’s disease
X-linked Adrenoleukodystrophy
Clinical features
Diagnosis
Treatment
Acknowledgements
References
22 Childhood Cancers
Introduction
Types of cancers seen in childhood
Aetiology of malnutrition in children with cancer
Identification of nutritional risk
Nutritional support
Nutrition and the child with cancer undergoing bone marrow transplant
Alternative diets
Vitamins and minerals
Glutamine
References
Useful addresses
23 Eating Disorders
Introduction
Eating disorders in a developmental context
Anorexia nervosa
Bulimia nervosa
Other eating difficulties associated with weight loss
Other eating difficulties associated with normal weight
Conclusions
References
Further reading
Useful address
24 Epidermolysis Bullosa
Introduction
Factors influencing nutritional status
General aims of nutrition support
Growth
Importance of early nutrition support
Weaning
Herlitz junctional EB
Non-Herlitz junctional EB
Recessive dystrophic EB
Dowling–Meara subtype of EB simplex
Vitamins
Biochemical and haematological estimations
Iron and anaemia
Zinc
Calcium and vitamin D, osteoporosis and osteopenia
Selenium and carnitine
Gastro-oesophageal reflux
Nasogastric feeding
Gastrostomy feeding
Painful defaecation with/without constipation
Dental aspects
Oesophageal dilatation and colonic interposition
References
Useful address
Useful fora, websites
25 Burns
Introduction
Assessment of injury
Metabolic response to burn injury
Aims of nutritional support
Assessment of nutritional requirements
Meeting nutritional goals
Monitoring
Case study
Acknowledgements
References
26 Autistic Spectrum Disorders
Introduction
Diagnosis and co-morbidities
Sensory issues
Causes of ASD
Treatment and management
Gastrointestinal issues and ASD
Nutritional or metabolic abnormalities in ASD
Dietetic challenges in ASD
Deal with underlying issues that may be exacerbating eating problems
Biomedical interventions: therapeutic diets for ASD
Acknowledgements
References
Further reading
Useful addresses
Resources advocating dietary interventions
Part 4 Community Nutrition
27 Healthy Eating
Introduction
Infants
Toddlers and young children under 5 years of age
Primary and secondary school children
Food safety
Controversial issues around nutrients and foods
References
Further reading and information
28 Children from Ethnic Groups and those following Cultural Diets
Introduction
Vegetarian and vegan diets
Asian diets
Afro-Caribbean diets
Chinese diets
Vietnamese diets
Somalian diets
References
29 Faltering Growth
Introduction
When does faltering growth become a cause for concern?
Recognition of faltering growth
Consequences of faltering growth
Prevalence of faltering growth
Contributing factors
Management of faltering growth
Nutritional management
Behavioural management
Social services
References
Further reading
30 Feeding Children with Neurodisabilities
Introduction
National Service Framework for Children and the social context
Medical conditions
Nutritional concerns
Feeding difficulties
Nutrition screening
Nutritional assessment
Nutritional requirements
Nutritional management
Nutritional monitoring
References
Useful address
3l Obesity
Introduction
Aetiology
Definition
Consequences
Assessment
Management
Prevention
Prader–Willi syndrome
References
Useful resources and addresses
32 Prevention of Food Allergy
Introduction
Strategies during pregnancy
Infant feeding strategies
Environmental strategies
Recommendations
References
Appendix I Manufacturers of Dietetic Products
Appendix II Dietetic Products
Index
© 1994, 2001, 2007 by Blackwell Publishing
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First edition published 1994
Second edition published 2001
Third edition published 2007
1 2007
ISBN: 978-14051-3493-4
Library of Congress Cataloging-in-Publication Data
Clinical paediatric dietetics/edited by Vanessa Shaw and Margaret Lawson. — 3rd ed.
p. cm.
Includes bibliographical references and index.
ISBN-13: 978-1-4051-3493-4 (hardback : alk. paper)
ISBN-10: 1-4051-3493-3 (hardback : alk. paper)
1. Diet therapy for children. I. Shaw, Vanessa. II. Lawson, Margaret, MSc.
RJ53.D53C58 2007
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2006034442
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Contributors
Liz Allott
Senior Lecturer in Dietetic Practice,
Faculty of Health and Social Work, University of Plymouth, Peninsula Allied Health Centre, College of St Mark and St John, Derriford Road, Plymouth PL6 9BH
Sarah Almond
Senior Paediatric Dietitian,
Chailey Heritage Clinical Services, Beggars Wood Road, North Chailey, East Sussex BN8 4JN
Eleanor Baldwin
Refsum’s Research Dietitian,
Nutrition & Dietetic Department, Chelsea & Westminster Hospital, 369 Fulham Road, London SW10 9NH
Zoe Connor
Community Paediatric Dietitian, Bromley NHS PCT, St Paul’s Cray Clinic, Mickleham Road, Orpington, Kent BR5 2RJ
Katie Elwig
Chief Paediatric Dietitian,
St Mary’s Hospital, Praed Street, London W2 1NY
Marjorie Dixon
Specialist Dietitian,
Great Ormond Street Hospital for Children NHS Trust, London WC1N 3JH
Stephanie France
Former Chief Paediatric Dietitian, Kings College Hospital, Denmark Hill, London SE5 9RS
Kate Grimshaw
Research Dietitian, University Child Health, Southampton General Hospital, Tremona Road, Southampton SO16 6YD
Joanne Grogan
Senior Dietitian, Royal Liverpool Children’s NHS Trust, Eaton Road, Liverpool L2 2AP
Claire Gurry
Senior Paediatric Dietitian, Central Manchester and Manchester Children’s University Hospitals NHS Trust, Charlestown Road, Blackley, Manchester M9 7AA
Kate Hall
Freelance Dietitian, kate-hall@tiscali.co.uk
Lesley Haynes
Specialist Dietitian, Great Ormond Street Hospital for Children NHS Trust, London WC1N 3JH
David Hopkins
Specialist Dietitian, Bristol Royal Hospital for Children, Paul O'Gorman Building, Bristol BS2 8BJ
Tracey Johnson
Specialist Dietitian, The Birmingham Children’s Hospital NHS Trust, Steelhouse Lane, Birmingham B4 6NH
Alison Johnston
Lead Clinical Specialist Dietitian (Diabetes), Royal Hospital for Sick Children, Yorkhill, Glasgow G3 8SJ
Caroline King
Clinical Lead and Specialist Neonatal Dietitian, Hammersmith Hospital, Du Cane Road, London W12 0HS
Julie Lanigan
Clinical Trials Co-ordinator/Specialist Research Dietitian, Institute of Child Health, 30 Guilford Street, London WC1N 1EH
Margaret Lawson
Former Nestlé Senior Research Fellow, Institute of Child Health, 30 Guilford Street, London WC1N 1EH
Helen McCarthy
Lecturer in Dietetics, School of Biomedical Sciences, University of Ulster, Cromore Road, Coleraine BT52 1SA
Anita MacDonald
Consultant Dietitian in Inherited Metabolic Disorders, The Birmingham Children’s Hospital NHS Trust, Steelhouse Lane, Birmingham B4 6NH
Sarah Macdonald
Specialist Dietitian, Great Ormond Street Hospital for Children NHS Trust, London WC1N 3JH
Gwynneth McGrath
Senior Dietitian, The Birmingham Children’s Hospital NHS Trust, Steelhouse Lane, Birmingham B4 6NH
Rosan Meyer
Paediatric Research Dietitian, Room 252 Norfolk Place, Imperial College St Mary’s Campus, London W2 1BG
Judy More
Freelance Paediatric Dietitian, London, www.child-nutrition.co.uk
Liz Neal
Research Dietitan, Institute of Child Health, 30 Guilford Street, London WC1N 1EH
Dasha Nicholls
Consultant Child and Adolescent Psychiatrist,
Head of Feeding and Eating Disorders Service, Great Ormond Street Hospital for Children NHS Trust, London WC1N 3JH.
Carolyn Patchell
Head of Dietetic Services, The Birmingham Children’s Hospital NHS Trust, Steelhouse Lane, Birmingham B4 6NH
Julie Royle
Chief Dietitian, Central Manchester and Manchester Children’s University Hospitals NHS Trust, Pendlebury, Manchester M27 4HA
Patricia Rutherford
Former Chief Dietitian, Royal Liverpool Children’s NHS Trust, Eaton Road, Liverpool, L12 2AP. Now Clinical Information Manager, Vitaflo International Ltd, 11–16 Century Building, Liverpool L3 4BL
Marian Sewell
Senior Dietitian, Great Ormond Street Hospital for Children NHS Trust, London WC1N 3JH
Vanessa Shaw
Head of Dietetics, Great Ormond Street Hospital for Children NHS Trust, London WC1N 3JH
Zofia Smith
Community Paediatric Dietitian, Parkside Community Health Centre, 311 Dewsbury Road, Beeston, Leeds LS11 5LQ
Laura Stewart
Community Paediatric Dietitian,
Royal Hospital for Sick Children, Sciennes Road,
Edinburgh EH9 1LF
Carina Venter
Senior Allergy Dietitian
(Research and Clinical), The David Hide Asthma and Allergy Research Centre, St Mary’s Hospital, Newport, Isle of Wight
Evelyn Ward
Senior Paediatric Dietitian, St James University Hospital NHS Trust, Beckett Street, Leeds LS9 7TF
Ruth Watling
Head of Dietetics, Royal Liverpool Children’s NHS Trust, Eaton Road, Liverpool L2 2AP
Fiona White
Chief Metabolic Dietitian, Central Manchester and Manchester Children’s University Hospitals NHS Trust, Pendlebury, Manchester M27 4HA
Vivien Wigg
Senior Dietitian, Great Ormond Street Hospital for Children NHS Trust, London WC1N 3JH
Sue Wolfe
Chief Paediatric Dietitian, St James University Hospital NHS Trust, Beckett Street, Leeds LS9 7TF
Foreword
It gives me great pleasure to write the foreword for the third edition of Clinical Paediatric Dietetics. This edition clearly shows the diversity of areas paediatric dietitians work within, from clinical dietetics to community nutrition. The new structure recognises the important extent of the role dietitians play in the health care of sick infants and children.
Recognition should be given to The Paediatric Group of the British Dietetic Association for their evidence based and practical approach. Vanessa and Margaret should once again be sincerely congratulated for managing contributions from almost 40 dietitians with valued input from a significant number of others – a task that would overwhelm many.
The value of this book is recognised not only by dietitians but also by many other health professionals as an excellent source of reliable information to ensure optimal nutritional care is given to sick infants and children.
Dame Barbara Clayton DBE
Honorary Research Professor in Metabolism,
University of Southampton
Honorary President, The British Dietetic Association
Preface
The aim of this manual is to provide a very practical approach to the nutritional management of a wide range of paediatric nutritional disorders that may benefit from nutritional support or be ameliorated or resolved by dietary manipulation. The text will be of particular relevance to professional dietitians, dietetic students and their tutors, paediatricians, paediatric nurses and members of the community health team involved with children requiring therapeutic diets. The importance of nutritional support and dietary management in many paediatric conditions is increasingly recognised and is reflected in new text for this edition.
The authors are largely drawn from practising paediatric dietitians around the United Kingdom, with additional contributions from academic research dietitians and a psychiatrist. The text has been reorganised for this edition and includes a thorough review of the scientific and medical literature to support practice wherever available. The major part of the text concentrates on nutritional requirements of sick infants and children in the clinical setting. Normal dietary constituents are used alongside special dietetic products to provide a prescription that will control progression and symptoms of disease whilst maintaining the growth potential of the child. There is a new section on community nutrition including healthy eating throughout childhood. We acknowledge that the distinction between clinical dietetics and nutrition in the community is rather arbitrary since many clinical conditions are dealt with in the community, and the principles of healthy eating underpin many clinical interventions.
New topics have been added: nutrition support in critical care, autistic spectrum disorders, prevention of food allergy. There has been an expansion of the range of disorders and treatments described in many chapters, e.g. gastroenterology, liver disease, gut transplantation, cardiac conditions, fatty acid oxidation defects; and new recommendations and guidelines for parenteral nutrition, feeding preterm infants and assessing children with neurodisabilities.
Arranged under headings of disorders of organ systems rather than type of diet, and with much information presented in tabular form and with worked examples, the manual is easy to use. Appendices list the many and varied special products described in the text, together with details of their manufacturers. The appendices are not exhaustive, but include the products most commonly used in the UK. The most recent information and data has been used in the preparation of this edition, but no guarantee can be given of the validity or availability at the time of going to press.
Vanessa Shaw
Margaret Lawson
Acknowledgements
We would like to thank a number of the contributors to the first edition, who were unable to contribute to the second edition, but whose work formed the basis for the following chapters:
We would like to thank a number of the contributors to the second edition, who were unable to contribute to this third edition, but whose work has formed the basis for the following chapters:
Chapter 1 Nutritional Assessment, Dietary Requirements, Feed Supplementation
Chapter 2 Provision of Nutrition in a Hospital Setting
This text provides a practical approach to the dietary management of a range of paediatric disorders. The therapies outlined in Parts 2 and 3 describe dietetic manipulations and the nutritional requirements of the infant and child in a clinical setting, illustrating how normal dietary constituents are used alongside special dietetic products to allow for the continued growth of the child while controlling the progression and symptoms of disease. Nutrition for the healthy child and nutritional care most often provided in the community setting is addressed in Part 4.
The following principles are relevant to the treatment of all infants and children and provide the basis for many of the therapies described later in the text.
Assessment and monitoring of nutritional status should be included in any dietary regimen, audit procedure or research project where a modified diet has a role. There are a number of methods of assessing specific aspects of nutritional status, but no one measurement will give an overall picture of status for all nutrients. There are several assessment techniques, some of which should be used routinely in all centres while others are still in a developmental stage or are suitable only for research. Figure 1.1 outlines the techniques that can be used for nutritional assessment.
For children over the age of 2 years food intake is assessed in the same way as for adults: using a recall diet history, a quantitative food diary over a number of days, a weighed food intake over a number of days or a food frequency questionnaire [1]. For most clinical purposes an oral history from the usual carers (or from the child if appropriate) will provide sufficient information on which to base recommendations. As well as assessing the range and quantity of foods eaten it is also useful to assess whether the texture and presentation of food is appropriate for the age and developmental level of the child. For instance, does the child use an infant feeding bottle or a cup; is the child able to self-feed or need a lot of help; is the food of normal consistency, as eaten by the family, or is it a smooth purée, chopped or mashed?
The assessment of milk intake for breast fed infants is difficult and only very general estimations can be made. Infants can be test-weighed before and after a breast feed and the amount of milk consumed can be calculated. This requires the use of very accurate scales (±1–2 g) and should be carried out for all feeds over a 24-hour period as the volume consumed varies throughout the day. Test-weighing should be avoided if at all possible as it is disturbing for the infant, engenders anxiety in the mother and is likely to compromise breast feeding. Studies have shown that the volume of breast milk consumed is approximately 770 mL at 5 weeks and 870 mL at 11 weeks [2]. In general, an intake of 850 mL is assumed for infants who are fully breast fed and over the age of 6 weeks, with additional intake from food at the appropriate weaning age. Estimation of food intake is particularly difficult in infants, as it is not possible to assess accurately the amount of food wasted through, for example, spitting or drooling.
Conversion of food intake into nutrient values for young children may involve the use of manufacturers’ data if the child is taking proprietary infant foods and/or infant formula. The composition of breast milk varies and food table values may be inaccurate by up to 20% because of individual variation.
Assessment of the adequacy of an individual calculated nutrient intake for sick and for healthy infants and children is discussed in the section on Dietary Reference Values (see p. 10).
Measurement of weight and height or length is critical as the basis for calculating dietary requirements as well as monitoring the effects of dietary intervention. Other anthropometric measurements are summarised in Table 1.1.
Head circumference
Head circumference is a useful measurement in children under the age of 2 years, particularly where it is difficult to obtain an accurate length measurement. After this age head growth slows and is a less useful indicator of somatic growth. A number of genetic and acquired conditions will affect head growth (e.g. neurodevelopmental delay) and measurement of head circumference will not be a useful indicator of nutritional status in these conditions. Head circumference is measured using a narrow, flexible, non-stretch tape. Details of a suitable disposable paper tape are available from the Child Growth Foundation (see p. 20). Measurement should be made just above the eyes to include the maximum circumference of the head, with the child supported in an upright position and looking straight ahead.
Weight
Measurement of weight is an easy and routine procedure using an electronic digital scale or a beam balance. Ideally, infants should be weighed nude and children wearing just a dry nappy or pants, but if this is not possible it is important to record whether the infant is weighed wearing a nappy, and the amount and type of clothing worn by older children. For weighing infants up to 10 kg, scales should be accurate to 10 g; for children up to 20 kg, accuracy should be ±20 g and over 20 kg it should be about 50–200 g. A higher degree of accuracy is required for the assessment of sick children than for routine measurements in the community. Frequent weight monitoring is important for the sick infant or child and hospitalised infants should be weighed daily if there are problems with fluid balance, otherwise on alternate days; children over the age of 2 years in hospital should be weighed at least weekly. Recommendations for the routine measurement of healthy infants where there are no concerns about growth are given in Table 1.2 [3]. If there are concerns about weight gain that is too slow or too rapid, measurement of weight should be carried out more frequently.
Measurement | Derived indices | Comments |
Head circumference | Head circumference for age | Easy to measure; useful up to the age of 2 years; useful as proxy for length increase; does not normally change rapidly Affected by medical condition; may not indicate nutritional status |
Weight | Weight for age | Easy to measure; useful on a day to day basis |
Weight for age z score | Does not differentiate between lean tissue, oedema and body fat | |
Length/height | Length/height for age | Not easy to measure accurately – needs more than one person to measure; does not change rapidly |
Length/height for age z score | ||
Height age | Best overall indicator of nutritional wellbeing | |
Weight for stature | Useful for children with low height age | |
Body mass index (W/H2) | BMI indicates relative weight for height, but does not differentiate between lean and fat tissue | |
Body mass index z score | ||
Mid arm circumference | Mid arm circumference for age | Easy to measure; useful up to the age of 5 years |
Mid arm circumference z score | Less likely to be affected by water retention or fat deposition than body weight | |
Skinfold thickness (SFT) | Triceps SFT for age | Difficult to measure accurately; unpleasant procedure for children Usually triceps only are used in children Distinguishes between lean and fat tissue |
Waist circumference | Waist circumference for age | Easy to measure, although requires removal of clothes Distinguishes between high weight due to muscle bulk and that due to fat |
Hip circumference | Waist : hip ratio | Easy to measure No standards for children |
Height
Height or length measurement requires a stadiometer or length-board. Details of suitable equipment, which may be fixed or portable, are available from the Child Growth Foundation. Measurement of length using a tape measure is too inaccurate to be of use for longitudinal monitoring of growth, although an approximate length may be useful as a single measure (e.g. for calculating body mass index). Under the age of about 2 years supine length is measured; standing height is usually measured over this age or whenever the child can stand straight and unsupported. When the method of measurement changes there is likely to be a difference in length, and measurements should be made by both methods on one occasion when switching from supine length to standing height. Measurement of length is difficult and requires careful positioning of the infant, ensuring that the back, legs and head are straight, the heels are against the footboard, the shoulders are touching the baseboard and the crown of the head is touching the headboard. Two people are required to measure length – one to hold the child in position and one to record the measurement. Positioning of the child is also important when measuring standing height and care should be taken to ensure that the back and legs are straight, the heels, buttocks, shoulder blades and back of head are touching the measurement board and that the child is looking straight ahead.
Source: After Health for all Children [3].
Weight | Length/Height | Head Circumference |
Birth 2 months | Birth 6–8 weeks if birthweight <2.5 kg or if other cause for concern | Birth or neonatal period 6–8 weeks |
3 months | ||
4 months | ||
8 months | ||
Additional weights at parent’s request, not more frequently than 2 weekly under the age of 6 months, monthly 6–12 months 12–15 months | No other routine measurement of length/height | No other routine measurement of head circumference |
School entry | School entry |
Sick infants should be measured every month and older children whenever they attend a clinic. Healthy infants have a length measurement at birth (although this is notoriously inaccurate) and no further height checks are recommended until the pre-school check [3]. Whenever there are concerns about growth or weight gain a height measurement should be made more often, although there is little point in measuring height more frequently than every 3 months.
Body mass index
A body mass index (BMI) measurement can be calculated from the weight and height measurements: BMI = weight (kg)/height (m)2. This provides an indication of fatness or thinness. In adults, body fatness is largely unrelated to age and high BMI measurements are related to health risks. In children, the amount and distribution of body fat is dependent on age, and does not appear to be related to health. At the extremes of centiles, BMI does not differentiate well between heaviness resulting from lean tissue (e.g. high muscle mass) and weight resulting from excess fat deposition, and further interpretation is necessary.
Proxy measurements for length/height
In some cases it is difficult to obtain length or height measurements (e.g. in very sick or preterm infants and in older children with scoliosis). A number of proxy measurements can be used which are useful to monitor whether longitudinal growth is progressing in an individual, but there are no recognised centile charts as yet and indices such as BMI cannot be calculated. In adults, arm span is approximately equivalent to height, but body proportions depend upon age and this measurement is not generally useful. Measurements of lower leg length or knee–heel length have been used and are a useful proxy for growth. For infants and small children, a kneemometer has been developed which displays knee–heel length digitally [4]. For older children knee–heel length is measured with the child in a supine position (if possible) with the knee bent at a 90° angle using a caliper with a blade at either end. One blade is fitted under the heel of the foot and the other onto the knee, immediately behind the patella, using the outside surface of the leg. Total leg length is rarely measured outside specialist growth clinics and is calculated as the difference between measured sitting height and standing height. A number of other measures have been used in children with cerebral palsy as a proxy for height, but numbers are too small for reference standards to be established [5]. Formulas for calculating height from proxy measurements are further discussed in Chapter 29.
Supplementary measurements
The measurement of weight and length or height forms the basis of anthropometric assessment. However, these measurements on their own do not indicate whether weight increments are due to lean and fat tissue, or whether weight gained is merely fat. Supplementary measurements that can be used include mid upper arm circumference (MUAC). This is a useful measurement in children under the age of 5 years, as MUAC increases fairly rapidly up until this age. Age related standards exist for children over the age of 1 year [6]. Increases in MUAC are more likely to comprise muscle and less likely to be affected by oedema than body weight. In order to fully differentiate between lean and fat, measurement of triceps skinfold thickness (TSF or SFT) is necessary. This can be an unpleasant procedure for young children, who are afraid of the skinfold caliper and may not remain still for long enough for accurate measurements to be taken. The equipment and technique are identical to those used in adults and the measurement is subject to the same observer error. Skinfold thickness is not used as a routine anthropometric measure but provides valuable data in research studies. Reference data for children over the age of 1 year are available [6] and the World Health Organization (WHO) will publish reference norms for children aged 1–5 in the near future. Arm muscle and arm fat area can be calculated and compared to reference data [6]. A calculation of arm fat and muscle area is shown in Table 1.3.
Measurement of the waist circumference can help distinguish between a high weight for age that is caused by high body lean tissue or high body fat. In general, children with a high weight for height or high BMI who have a high muscle bulk (usually resulting from sports training) will have a low waist circumference centile, while overweight and obese children will have a high waist centile. The waist : hip ratio in children has not proved to be a useful predictor of obesity in pre-pubertal children [7], and reference data do not exist at present for European children.
Measurements should be regularly plotted on the relevant centile chart using a dot rather than a cross or a circle. All children in the UK are issued with a growth centile chart as part of the personal child health record that is held by parents and completed by health care professionals whenever the child is weighed or measured. UK centile charts are available for weight, length/height, head circumference and BMI and the standard ones in use are based on the UK 1990 data [8]. These data were based on a cohort of infants who were largely formula fed during the first 6 months of life. The growth of breast fed infants differs from that of artificially fed infants, and breast fed infants tend to be longer and leaner at age 3 months [9]. Centile charts for fully breast fed infants are available from the Child Growth Foundation, and can be used for both breast and formula fed infants; however, they are based on a very small cohort of 120 infants who had solids introduced at a mean age of 15 weeks and only 40% were still receiving breast milk at 1 year of age. The WHO has produced growth charts based on a sample size of 8440 children for longitudinal and cross-sectional study from ethnically diverse populations across the globe [10]. These children were raised in optimal conditions including exclusive or predominant breast feeding for at least 4 months, introduction of complementary foods by 6 months of age and continued partial breast feeding to at least 12 months of age. These charts may be more suitable than the standard UK 1990 charts for infants and children who are recent immigrants to the UK.
Age related centile charts for BMI have been developed [11] and indicate how heavy the child is relevant to their height and age. Waist circumference centile charts are also available for British children over the age of 3 years [12]. Some medical conditions have a significant effect on growth, and where sufficient data exist, for instance in Down’s syndrome, Turner’s syndrome and sickle cell disease, separate growth charts have been developed for these conditions [13], and are available from the Child Growth Foundation.
There are a number of problems associated with accurate plotting on charts that can lead to inaccuracies in monitoring. Charts may give time increments in months or may require the decimal age to be calculated using the decimal age calendar on the centile charts, and it is important to check which type of chart is being used. In a clinic or a centre where a number of people are involved in plotting measurements, agreement should be reached over whether values that fall between centiles should be rounded up or rounded down. Variations in procedures can result in relatively large errors, particularly in infants, and deviations from centiles can be missed. When assessing height it is important to take parental height into consideration, and the genetic height potential for the child can be approximately estimated using the mid-parental height +7 cm for boys, and the mid-parental height –7 cm for girls. This calculation is not appropriate if either parent is not of normal stature. The UK 1990 growth charts give example calculations for adult height potential. (For definitions of obesity and failure to thrive see Chapters 29 and 31.)
It is difficult to assess progress or decide upon targets where a measurement falls outside the centile lines: either <0.4th centile or >99.6th centile. Amended weight charts showing up to ±5 standard deviations for monitoring children with slow weight gain are available [14]; details from the Child Growth Foundation. ‘Thrive lines’ have also been developed to aid interpretation of infants with either slow or rapid weight gain. The 5% thrive lines define the slowest rate of normal weight velocity in healthy infants. If an infant is growing at a rate parallel to or slower than a 5% thrive line, weight gain is abnormally slow. The 95% thrive lines define the most rapid rate of normal weight gain in healthy infants and weight gain that parallels or is faster than the 95% thrive line is abnormally rapid [14]. Thrive lines are in the form of an acetate sheet which overlays either the standard A4 weight centile charts or charts in the personal child health record. Acetates are available from the Child Growth Foundation.
There are a number of methods of overcoming problems in plotting onto charts, which involve converting the weight and height into a finite proportion of a reference or standard measurement. Calculation of the standard deviation score (SDS) or z score for length/height, weight and BMI gives a numerical score indicating how far away from the 50th centile for age the child’s measurements falls. A child on the 0.4th centile will have a SDS of –2.65 SD. A child on the 99.6th centile will have a SDS of +2.65 SD, while a measurement that falls exactly on the 50th centile will have a z score of 0. Because of the distribution of the data, calculation of z scores by hand is extremely laborious. A computer software program is available from the Child Growth Foundation that will calculate z scores from height, weight and age data. The z score is also used when comparing groups of children of different genders or ages, when a comparison of the measurements themselves would not be useful.
The calculation of height for age, height age and weight for height are useful when assessing nutritional status initially or when monitoring progress in children who are short for their chronological age. Table 1.4 shows examples of calculations for these measurements. Calculation of height age is necessary when determining nutrient requirements for children who are much smaller (or larger) than their chronological age (see p. 12).
A number of methods of classification of malnutrition have been used in developing countries. The Waterlow classification [15] may be of use when assessing children in the UK with severe failure to thrive. An adaptation of the classification is shown in Table 1.5. The WHO defines malnutrition as moderate if the weight for age z score is less than –0.2 and severe if the weight for age z score is less than –0.3 [16].
Source: After Waterlow [15].
Acute malnutrition (wasting) | Chronic malnutrition (stunting ± wasting) |
Weight for height | Height for age |
80–90% standard – grade 1 | 90–95% standard – grade 1 |
70–80% standard – grade 2 | 85–90% standard – grade 2 |
<70% standard – grade 3 | <80% standard – grade 3 |
Clinical assessment of the child involves a medical history and a physical examination. The medical history will identify medical, social or environmental factors that may be risk factors for the development of nutritional problems. Such factors include parental knowledge and money available for food purchase, underlying disease, changes in weight, food allergies and medications. Clinical signs of poor nutrition, revealed in the physical examination, only appear at a late stage in the development of a deficiency disease and absence of clinical signs should not be taken as indicating that a deficiency is not present. Typical physical signs associated with poor nutrition that have been described in children in western countries are summarised in Table 1.6. Physical signs represent very general changes and may not be caused by nutrient deficiencies alone. Other indications such as poor weight gain and/or low dietary intake are needed in order to reinforce suspicions, and a blood test should be carried out to confirm the diagnosis.
Food and nutrient intake, anthropometric measurements and clinical examination and history form the basis of routine nutritional assessment. None of these are diagnostic tests and can only predict which nutrients may be deficient and which children need further investigation. If a nutrient deficiency (or excess) is suspected as a result of the first line assessment tools, then confirmation using other objective measures should be sought.
Methods of confirming suspicion of a nutritional problem include analysis of levels of nutrients or nutrient-dependent metabolites in body fluids or tissues, or measuring functional impairment of a nutrient-dependent metabolic process.
Assessment | Clinical sign | Possible nutrient(s) |
Hair | Thin, sparse Colour change – ‘flag sign’ Easily plucked |
Protein and energy, zinc, copper |
Skin | Dry, flaky | Essential fatty acids B vitamins |
Rough, ‘sandpaper’ texture | Vitamin A | |
Petechiae, bruising | Vitamin C | |
Eyes | Pale conjunctiva | Iron |
Xerosis | Vitamin A | |
Keratomalacia | ||
Lips | Angular stomatitis Cheilosis | B vitamins |
Tongue | Colour changes | B vitamins |
Teeth | Mottling of enamel | Fluorosis (excess fluoride) |
Gums | Spongy, bleed easily | Vitamin C |
Face | Thyroid enlargement | Iodine |
Nails | Spoon shape, koilonychia | Iron, zinc, copper |
Subcutaneous tissue | Oedema | Protein, sodium |
Over-hydration | ||
Depleted subcutaneous fat | Energy | |
Muscles | Wasting | Protein, energy, zinc |
Bones | Craniotabes | Vitamin D |
Parietal and frontal bossing | ||
Epiphyseal enlargement Beading of ribs |
The most commonly used tissue for investigation is the blood. Whole blood, plasma, serum or blood cells can be used, depending on the test. Tests may be static (e.g. levels of zinc in plasma) or may be functional (e.g. the measurement of the activity of glutathione peroxidase, a selenium-dependent enzyme, as a measure of selenium status). Although an objective measurement is obtained from a blood test, there are a number of factors that can affect the validity of such biochemical or haematological investigations. Age specific normal ranges need to be established for the individual centre unless the laboratory participates in a regional or national quality control scheme. Recent food intake and time of sampling can affect levels and it may be necessary to take a fasting blood sample for some nutrients. Physiological processes such as infection, disease or drugs may alter normal levels. Contamination from exogenous materials such as equipment or endogenous sources such as sweat or interstitial fluid is important for nutrients such as trace elements, and care must be taken to choose the correct sampling procedure. A fuller review of the subject is given by Clayton & Round [17]. A summary of some biochemical and haematological measurements is given in Table 1.7.
Urine is often used for adult investigations, but many tests require the collection of a 24-hour urine sample and this is difficult in babies and children. The usefulness of a single urine sample for nutritional tests is limited and needs to be compared with a standard metabolite, usually creatinine. However, creatinine excretion itself is age dependent and this needs to be taken into consideration. Hair and nails have been used to assess trace element and heavy metal status in populations, but a number of environmental and physiological factors affect levels and these tissues are not routinely used in the UK. Tissues that store certain nutrients, such as the liver and bone, would be useful materials to investigate, but sampling is too invasive for routine clinical use.
A number of other tests that are indicative of nutritional status may provide useful information but are not available routinely. Measurement of body composition using isotope dilution or imaging techniques is particularly useful for the clinical dietitian as most methods of assessment do not indicate whether growth consists of normal ratios of fat and protein or whether excess amounts of adipose tissues are being accumulated. Body composition measurements are described by Ruxton et al. [18]. The use of bioimpedance (BIA) in assessing body composition in adults has increased since the development of relatively inexpensive and user friendly equipment (‘Body Fat Analysers’). However, this method assumes a constant state of hydration, which has shown not to be true for obese individuals. In addition the method has not been validated for use in children and young people under the age of 18 years [19].
Tests that are not routinely carried out but that may be useful research tools are summarised in Table 1.8.
The 50th centile birthweight for infants in the UK is 3.5 kg. There is some weight loss during the first 5–7 days of life while feeding on full volumes of milk is established; birthweight is normally regained by the 10th to 14th day. Thereafter, average weight gain is as follows:
Increase in length during the first year of life: 25 cm.