University Cl~ildret~'~ Ilospital. Ilci(lc~lhc~r,y, Gcrrtlro~y /F.S., ;\I.G., K.S../ ut~d hr~rcI.ar Rcscw-ch Coltrc~.Kurl.tr~rlrc, Gcrr)lunjv [..I .%.I ABSTRACT. Despite the increasing use of tetrapolar TBK, total body potassium whole-body bioelectric impedance (BI) analysis in the as-CV, coefficient of variation sessment of body composition, its usefulness in estimating RhISE, root mean square error fat-free mass (FFR.1) has not been evaluated in comparison with conventional skinfold anthropometry in children. We therefore compared I) the intraobserver and interobserver reproducibility of BI and skinfold measurements and the Within the past few years, BI analysis has gained wide use in derived FFhl estimates, and 2) the predictability of FFhI the assessment of body composition. The method appears para s calculated from measurements of total body potassium ticularly suitable for use in children, because the measurements (TBK) using ' "K spectrometry by equations based on either are fast, noninvasive, painless, and require little subject cooper-BI or skinfold measurements in 112 healthy children, ation. The BI technique is based on the difference in specific adolescents, and young adults aged 3.9 to 19.3 y. best-resistance to an electrical current between aqueous and nonfitting equation to predict TBK-derived FFhl from BI and aqueous compartments within the body. Validation studies have other potential independent predictors was developed and shown the accuracy and precision of the technique to be at least cross validated in two randomly selected subgroups of the comparable with conventional anthropometric methods such as study population by stepwise multiple regression analysis. skinfold thickness measurements in both adults and children Although the technical error associated with BI measure-(1-4). ments was much smaller than that of skinfold measure-The few studies performed so far in children suggest that the mcnts, the reproducibility of BI-derived FFhl estimates changing proportions of body fluid compartments during child-(intraobserver coefficient of variation [CV], 0.39%; inter-hood may require the use of specific pediatric prediction equaobserver CV, 1.2370) was only slightly better than that of tions (4-7). However, the validation methods used so far are FFhI estimates obtained by use of weight and two skinfold difficult to apply in smaller children or rely on a number of measurements (0.62% and 1.39%, respectively). 'l'he cross unverifiable assumptions. Densitometric underwater weighing validation procedure yielded the following best-fitting pre-and respirometric assessment of residual lung volume require diction equation: FFhI = 0.65. (height2/impedance) + full subject cooperation. In addition, the specific density of the 0.68.age + 0.15 (Rz = 0.975, root mean square error = FFM seems to change during childhood; variable-density FFM 1.98 kg, CV = 5.8%, 95% limits of agreement = -1 1.1% models have been applied but are hypothetical (4, 8). Isotope to +12.470). Conventional anthropometry, using publi...

The clinical course of 66 boys and 49 girls with autosomal recessive polycystic kidney disease recruited from departments of paediatric nephrology was investigated over a mean observation period of 4.92 years. This is a selected study group of children from departments of paediatric nephrology who in most cases survived the neonatal period, since birth clinics did not participate. The median age at diagnosis was 29 days (prenatal to 14.5 years). We observed decreased glomerular filtration rates (GFRs) in 72% (median age at onset of decrease of GFR < 2 SD, 0.6 years; range, 0-18.7 years), and 11 patients developed end-stage renal disease. Hypertension requiring drug treatment was found in 70% (median age at start of medication, 0.5 years; range, 0-16.7 years). Kidney length was above the 97th centile in 68% of patients, and kidney length did not increase with age or deterioration of renal function. Urinary tract infections occurred in 30%, growth retardation in 25%, and clinical signs of hepatic fibrosis were detected in 46%. Thirteen patients (11%) died during the observation period, 10 of them in the first year of life. There was a statistically significant sex difference in terms of a more pronounced progression in girls. The survival probability at 1 year was 94% for male patients and 82% for female patients (p < 0.05) in this study. Urinary tract infections occurred more frequently in girls (p < 0.025) and were observed earlier. In addition, more girls had impaired renal function, developed end-stage renal disease and showed growth retardation; these differences, however, were not significant. For the children in this study, however, our results indicate that the long-term prognosis in the majority of cases is better throughout childhood and youth than often stated.

We studied the long-term outcome of 64 children with biopsy-proven Schönlein-Henoch purpura (SHP) nephritis over 1-23 years of follow-up. Overall renal survival 10 years after onset was 73%. Multivariate logistic regression analysis identified initial renal insufficiency (P=0.004), nephrotic syndrome (P=0.037), and the severity of histological alterations, as defined by the proportion of glomerular crescents (P=0.051), as significant independent predictors of progressive renal failure. Four patients followed for more than 19 years showed glomerular damage after transient recovery. Eight children with crescentic nephritis associated with a rapidly progressive course and/or persistent nephrotic syndrome were treated by at least seven sessions of plasma exchange (PE) within 16 weeks of onset of purpura. During treatment serum creatinine levels dropped in each patient from a mean of 2.3 to 1.1 mg/dl, followed by a rebound increase. Repeated courses of PE in 5 patients produced comparable responses. Four patients undergoing PE reached end-stage renal disease at 1.2.-3.7 years after onset, whilst 3 finally were in preterminal renal failure (creatinine 3.2-6.1 mg/dl after 7-13.5 years), and 1 patient reached a normal glomerular filtration rate. Our experience suggests that initial renal insufficiency is the best single predictor of the further clinical course in children with SHP nephritis. Early PE appears to delay the progression in some patients with severe, rapidly progressive forms of the disease.