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The aim of this study was to assess body composition in children with chronic renal failure (CRF) and post renal transplantation (Tx), and to compare it to body mass index (BMI) and nutritional intake. Dietary assessment using 3-day diaries, total and regional body composition assessment by dual x-ray energy absorptiometry of 50 CRF children (29M, 21F), median age 8.9 yrs and 50 Tx children (32M, 18F), median age 12.9 yrs. BMI, percentage fat mass (%FM) and lean mass (LM) were corrected for height and expressed as SDS (HSDS). In both groups, BMIHSDS was lower than %FMHSDS and higher than LMHSDS (p<0.05). In the Tx group, there were associations on bivariate analysis between energy & protein intake and BMIHSDS & %FMHSDS (r,0.5, p<0.05), and between LMHSDS and protein intake (r,0.5, p<0.05). On multivariate analysis, there was an association between LMHSDS and time since transplantation (r,-0.4, p<0.05). Children in the CRF and Tx groups had a high percentage predicted trunk:leg FM ratio of 148% and 157%, respectively. Children with CRF and Tx have discordant body composition with a relatively high FM and low LM, which is not reflected by BMI. In addition, they appear to have an increased level of central adiposity that may predispose them to increased morbidity in later life.

The combination of poor growth and parathyroid and mineral disorders complicates the diagnosis of renal bone disease in children with chronic renal insufficiency (CRI), and the role of dual X-ray absorptiometry (DXA) is unclear. We aimed to examine the role of DXA in assessing variation in size-adjusted bone mineral content (BMC) in children with CRI and compare it with a cohort with hypoparathyroidism (HPT) and pseudo-hypoparathyroidism (PHPIa). In 29 patients with CRI (21 male) with a median age of 11 years (10th, 90th centiles 4.4, 14.6) and 10 patients with HPT and PHPIa (three male), with a median age of 13.7 years (7, 16) lumbar spine (LS) and total body (TB) BMC were measured by DXA. Age-, gender- and height-matched data allowed calculation of percentage predicted bone area for age and gender (pBAr) and percentage predicted BMC for bone area and height. In the CRI group, the median glomerular filtration rate (GFR) was 27.4 ml/min per 1.73 m2 (7.1, 69.5), and the median duration of illness was 9.3 years (2.1, 12.1). Median height standard deviation score (Ht SDS) was −1.6 (−3.0, 0.3), and, as expected, median LS and TB pBAr were low at 82% (68, 974) and 76% (63, 92), respectively. LS and TB predicted BMC (pBMC) SDS (corrected for bone size) were generally high, with a median value of 0.4 (−0.9, 1.4) and 0.4 (−0.1,0.9), respectively. Analysis of the prepubertal subset of children ( n=15) showed that median percentage predicted LS BMC for height was 104% (80, 116), whereas the median TB BMC for height was 96% (74, 108). Median Ht SDS of the HPT and PHPIa cohort was −0.3 (−2.9, 0.3) and median LS and TB pBAr were 90% (66, 100) and 91% (76, 98), respectively. Median LS and TB pBMC SDS were 0.6 (−0.4, 1.8) and 0.7 (0.3, 1.1), respectively. Median percentage predicted LS and TB BMC for height were 102% (82, 114) and 102% (92, 122). There was no relationship between pBMC SDS and duration of illness, GFR, vitamin D dose, serum intact parathyroid hormone (PTH), serum calcium/phosphate product or serum total alkaline phosphatase (ALP) in the CRI or the HPT cohort. However, one of the highest pBMC SDSs was recorded in a child with PHPIa before she started on any treatment. In children with CRI, BMC, when adjusted for co-existing growth retardation, is similar to that observed in children with hypoparathyroidism. The correct reading of BMC needs a correction for bone size. [ABSTRACT FROM AUTHOR]