RESUMO
OBJECTIVE: The 2H dilution technique is the reference method to estimate total body water for body composition assessment. The aims of the present study were to establish the total body water technique at the Kuwait Institute for Scientific Research and assess body composition of Kuwaiti children. DESIGN: The isotope ratio mass spectrometer was calibrated with defined international reference water standards. A non-random sampling approach was used to recruit a convenience sample of Kuwaiti children. A dose of 2H2O, 1-3 g, was consumed after an overnight fast and 2H enrichment in baseline and post-dose urine samples was measured. Total body water was calculated and used to estimate fat-free mass. Fat mass was estimated as body weight minus fat-free mass. SETTING: The total body water study was implemented in primary schools. SUBJECTS: Seventy-five boys and eighty-three girls (7-9 years). RESULTS: Measurements of the isotope ratio mass spectrometer were confirmed to be accurate and precise. Children were classified as normal weight, overweight or obese according to the WHO based on BMI-for-age Z-scores. Normal-weight and overweight girls had significantly higher percentage body fat (median (range): 32·4 % (24·7-39·3 %) and 38·3 % (29·3-44·2 %), respectively) compared with boys (median (range): 26·5 % (14·2-37·1 %) and 34·6 % (29·9-40·2 %), respectively). No gender difference was found in obese children (median 46·5 % v. 45·6 %). CONCLUSIONS: The establishment of a state-of-the-art stable isotope laboratory for assessment of body composition provides an opportunity to explore a wide range of applications to better understand the relationship between body size, body composition and risk of developing non-communicable diseases in Kuwait.