Sex differences in the long-term outcome after a severe thermal injury

We have recently shown that during the acute phase, postburn female pediatric burn patients had significantly increased levels of anabolic hormones with an associated decreased hypermetabolism leading to a significant shorter intensive care unit stay compared with male patients. The aim of the present study was to determine possible differences between girls and boys in body composition, hypermetabolism, and hormone pattern in the long term. Sixty-two children (1-16 years old) who sustained a severe thermal injury (≥40% total body surface area) were included into the study. Patients were further divided into girls (n = 22) and boys (n = 40). Patient demographics, nutritional support, and mortality were noted. Resting energy expenditure (REE) was measured by indirect calorimetry, body composition by dual-energy x-ray absorptiometry (Hologic Inc, Waltham, Mass) at discharge, 3, 6, 9, 12, 18, and 24 months after burn. In addition, blood was drawn at the same time points, and serum hormones were measured. There were no significant differences between girls and boys for demographics, nutritional intake, or concomitant injuries. Predicted REE was significantly decreased in girls at discharge, 6, 12, and 18 months postburn (P < 0.05). Dual-energy x-ray absorptiometry scan showed that girls had improved change in bone mineral content and percent fat compared with boys (P < 0.05). There were no differences in changes in height, body weight, lean body mass, and total fat between groups. Girls had significantly higher levels of insulinlike growth factor 1, insulinlike growth factor binding protein 3, free thyroxine index, T4, and insulin when compared with boys (P < 0.05). No differences were found for T3 uptake, osteocalcin, cortisol, growth hormone, and parathyroid hormone (PTH) between groups. Data indicate that girls have a reduced REE associated with changes in bone content and endogenous anabolic hormones.