Background: There is no knowledge of the energy metabolism in the presence of X chromosome aneuploidy or structural aberrations. Recently, an abnormal muscle metabolism was observed in girls with Turner syndrome (TS).
Objective and Hypotheses: Resting energy expenditure was prospectively estimated by indirect spirometry in 92 short prepubertal girls at the start of GH therapy.
Method: The diagnoses were TS (n=23), GH deficiency (GHD) (n=41) and SGA short stature (SGA) (n=28). Mean ages were 8.2 years (TS), 7.0 years (GHD) and 6.8 years (SGA). Mean heights (Prader reference) were −2.90 SDS (TS), −3.31 SDS (GHD) and −3.68 SDS (SGA). In TS, karyotypes were 45,X (n=15), 45,X/46,XX (n=3), 46,X,i(Xq) (n=1) and other X chromosome abnormalities (n=4). GHD was defined by growth failure, bone age retardation, low IGF1 and two GH test peaks <10 μg/l. SGA was defined by birth length or weight <−2 SDS and an actual height <−2.5 SDS. Spirometry (Vmax Encore 229) was performed under fasting conditions in the morning in a lying position. Body composition was measured by DXA simultaneously in 36 girls (TS, n=9).
Results: Girls with TS had significantly higher resting energy expenditure (mean±S.D.; 1114±215 kcal/day) than the other girls (820±169 kcal/day) (P<0.0001). In multiple linear regression analysis, the presence of TS was a strong independent predictor of resting energy expenditure (P<0.001) besides age (P<0.001) and BMI (P=0.034). GHD was no predictor (P=0.822). Mean lean body mass (DXA) was 15.2 kg (69%) in TS, 13.2 kg (73%) in GHD and 12.2 kg (81%) in SGA.
Conclusion: In short girls with TS the resting energy expenditure is significantly increased in comparison to short girls with GHD or SGA. The underlying mechanisms are unknown. High lean body mass and altered muscle metabolism in TS may play a role.
20 - 22 Sep 2014
European Society for Paediatric Endocrinology