Changes in body composition of children with chronic renal failure on growth hormone

Body composition is altered in children with chronic renal failure (CRF) and contributes to the significant growth failure seen in these children. Recombinant human growth hormone (rhGH) has been used in the past several years to improve the somatic growth of children with CRF. To determine if the growth achieved in these children occurs concomitantly with body compositional changes, seven prepubertal (n = 6) and pubertal (n = 1) children with chronic renal insufficiency (n = 4) and end-stage renal disease (n = 3) underwent measurements of total body fat (FM), fat free mass (FFM), bone mineral density (BMD), total bone mineral mass (TBBM), total body water (TBW), and total body potassium (TBK) before and 6 months after initiation of subcutaneous recombinant human growth hormone (rhGH) at 0.35 mg/kg per week. The techniques used included dual-energy X-ray absorptiometry (for measurement of FM, BMD, and TBBM), total body potassium counting (for measurement of TBK), and deuterated water for assessment of TBW. Significant increases in both height and weight were seen following 6 months of rhGH therapy. These increases were accompanied by significant reductions in FM (4.4 ± 1.4 kg vs. 3.6 ± 1.2 kg, P = 0.002) and percentage fat (18.6 ± 3.9% vs. 14.5 ± 3.4%, P = 0.04), while FFM (17.9 ± 3.0 kg vs. 20.7 ± 3.6 kg, P = 0.04) increased significantly as did TBBM (776 ± 171 g vs. 844 ± 177 g, P = 0.001). Increases in TBK, a measure of body cell mass, were also seen. No difference in total BMD was observed. Thus, growth in CRF is occurring with repletion of the FFM and TBBM compartments. Despite these improvements, no change was observed in the body mass index (BMI). Measurement of BMI alone does not define the compartmental catabolic losses in FFM.