An experimental estimate of the maintenance energy requirement in children with cystic fibrosis.

ABSTRACT

OBJECTIVE: To determine experimentally the maintenance energy requirement MER of children with Cystic Fibrosis (CF). DESIGN: Paired energy balance studies were undertaken on eight children with CF during an infection exacerbation, each child was his own control. SETTING: Paired energy balance (EB) studies at home over three days. SUBJECTS: Children known (from clinic records) to be susceptible to frequent infections were contacted. Four eligible children volunteered and completed two studies. INTERVENTION Energy intake was estimated by weighted dietary inventory during days 1-3 and 16-18 of convalescence and obligatory energy losses determined by analysis of synchronous faecal and urinary collections using bomb calorimetry and urea concentration respectively Resting energy expenditure (EE) was determined using the DeltatrakTM100 Metabolic Monitor Apparent energy balance (B) was calculated by difference between metabolizable energy intake ME and EE such that B = ME - EE. RESULTS: The linear relationship between B (y) and ME (x) is given by y = 0.85x - 206.6 (1) when B = 0, ME = MER with a value of 243.1kJ/kg/24h(95% CL 136.9 and 410.3kJ/kg/24h). CONCLUSION: When MER = 243.1 + 167.2 - 106.2kJ/kg/24h and ME = 93% of gross energy (GE), a GE intake of 261kJ/kg/24h(95% CL of 440kJ/kg/24h) meets the MER, and negative EB is avoided. Agreement with previous estimates of MER suggests no enhancement of MER in CF.