Resting energy expenditure in children with phenylketonuria.

Reports have suggested that children with phenylketonuria (PKU) weigh more compared with reference data. We found lower body protein and bone mineral density in children with PKU. These children may have a predisposition becoming overweight because of an alteration in body composition, which may lower resting energy expenditure (REE). REE was measured in 30 (15 males, 15 females) children with PKU (aged 9.6 +/- 2.9 y) and in 65 (23 males, 42 females) control children (aged 11.2 +/- 3.1 y). There was a comparable range in body fat within each group (control group: 11-34%; PKU group: 10-34%). The mean REE was similar between the male and female children with PKU (5300 +/- 757 and 4703 +/- 1024 kJ/24 h, respectively) and the control subjects (5306 +/- 969 and 5164 +/- 701 kJ/24 h, respectively). The children with PKU had an REE similar to that predicted from control data (males 102.1 +/- 7.8% of predicted and females 100.2 +/- 8.5% of predicted). This study found no evidence of a reduced REE or of increased weight in children with PKU.