Energy Requirements of Infants and Young Children with Prader-Willi Syndrome: With and Without Growth Hormone Therapy

Laura F. Goodwin, Joanna M. Ornoch, Karen Balko, Glenn Berall

North York General Hospital, Paediatic Outpatient Clinic, Toronto, Ontario, Canada

Objectives: The energy requirements of infants and young children with Prader-Willi Syndrome (PWS) are unknown. Current practice utilizes energy recommendations based on calories per centimetre of height. This method is not specific to metabolic needs. The objectives of this study were to determine the energy requirements of infants and children with PWS with or without growth hormone therapy, while considering the genetic subtype, and compare these energy requirements to age-matched children in the literature.

Methods: A retrospective chart review of patients at the North York General Hospital Paediatric Outpatient clinic under the age of seven years with genetically diagnosed PWS (n=20 patients). Data collected included age, gender, height, weight, measured resting energy expenditure (mREE), genetic diagnosis, and growth hormone treatment. Statistical analysis using SPSS 13.0 was conducted to determine if a significant difference exists between measured and predicted energy needs at p<0.05.

Results: The mREE was determined to be 44.77±9.89 kcal/kg and 6.5±1.47 kcal/cm for the total group. This is significantly lower than predictions using the current practice of calories per centimeter of height (56.22±11.52 kcal/kg, p<0.001and 8 kcal/cm, p<0.001) and the WHO standards for age-matched children (54.38±5.24 kcal/kg, p=0.001 and 7.97±1.29 kcal/cm, p<0.001). No significant difference was found in mREE (kcal/kg and kcal/cm) between males and females, and between the genetic subtypes. No significant difference was found between the two prediction methods. The pre and post GH population showed mREE of 47.3±9.3 kcal/kg (pre) and 51.7±11.5 kcal/kg (post/on). Given the small sample (n=3), we are unable to determine significance at this time.

Conclusions: The lower metabolic need suggests that infants and young children with PWS may be overfed even prior to onset of hyperphagia if the calories per centimetre standards developed in older patients are applied to this group of young children with PWS. This data also suggests that best practice for this population would include conducting basal metabolic rate testing on a regular basis as a standard method of energy requirement assessment. Through examination of mREE, energy requirements for proper growth, development and prevention and/or treatment of obesity or undernutrition in infancy and early childhood, can be determined to better guide clinicians in prescribing appropriate amounts of calories for their patients with PWS. Further studies with larger study samples are necessary to determine new standards for mREE in young children with PWS and the role of growth hormone therapy on energy requirements.