Background: Long standing GH deficiency (GHD) causes loss of muscle mass. DXA enables the measurement of LBMDXA but is accompanied with a potentially harmful X-ray exposition. BIA measures the electric resistance of the body which correlates with LBM. A comparison of both methods in children with GHD has not been performed yet.
Aim: Calculation of a regression formula for LBM using resistance and anthropometry based on LBMDXA in children with GHD.
Method: We recruited 120 prepubertal children (31 females) with GHD defined as growth failure, bone age retardation, low IGF1 and two GH test peaks <10 μg/l (mean±S.D.; age 7.68±2.96 years, peak GH 5.72±1.76 ng/ml). Height (ht), weight (wt), LBM by DXA (Lunar, DPXL/PED), resistance (R) and reactance (Xc) by BIA (BIA 2000-M) were measured before the start of GH therapy. Using multiple stepwise regression analysis we established a formula to calculate LBM based on age, height, weight, R and Xc.
Results: The best equation formula calculated was LBMBIA (kg)=233.64×ht (cm)+181.41×wt (kg)−6.89×R (Ω)−9421.74 (R=+0.98). Comparison of LBMBIA and LBMDXA by BlantAltman plot gave a mean difference of −0.075±0.923 kg within an LBMDXA range of 730 kg. In an individual patient the delta between LBMBIA and LBMDXA were up to 3 kg at an LBMDXA of 30 kg.
Conclusion: Calculation of LBM with help of anthropometry and BIA shows a good correlation with measured LBM in the total group of GHD patients, but in individual patients there is a broad variation between measured and calculated LBM.
20 - 22 Sep 2014
European Society for Paediatric Endocrinology