Peritoneal protein loss in children with nephrotic syndrome during peritoneal dialysis

Background: The passage of proteins across theglomerular filtration barrier is mainly determined by the size of theprotein. In nephrotic syndrome (NS) the glomerular permselectivity isaffected, causing proteinuria. Some authors suggest the existence of ageneralized basement membrane defect. The permeability characteristics ofthe peritoneal basement membrane in children with NS are not known.Methods: The transperitoneal transport of proteinswith a different molecular weight ({beta}2-microglobulin MW 11 800 D,albumin MW 69 000 D, IgG MW 160 000 D, and &agr;2-macroglobulin MW 820000 D) was studied in a study group (group A) consisting of six stablenephrotic children (three with glomerulosclerosis and three with congenitalnephrotic syndrome, one of them with mesangial sclerosis) and compared to acontrol group (group B) consisting of eight stable children on peritonealdialysis. After a dwell of 6 h with Dianeal 1.36% dialysate and serumsamples were collected. For each patient the dialysate to plasma (D/P)ratio of the four proteins were calculated. The D/P ratios of the nephroticpatients in group A were compared to the D/P ratios of the patients in thecontrol group B. Data were expressed as mean ±SD.Results: The values for the D/P ratios (in percentage)of {beta}2-microglobulin, albumin, IgG and &agr;2-macroglobulin ingroup A were 19.6±9.9, 2.7±1.7, 1.6±0.9,and 0.5±0.4, compared to 24.9±10.2,4.0±2.3, 2.2±1.2, and 0.7±0.3 in thecontrol group B. The ratios were plotted against MW on a double logarithmicscale. In all patients a linear relationship between molecular weight andD/P ratio of the proteins was obtained. The D/P ratios of the study groupdid no differ significantly from the control group.Conclusion: We conclude that the size selectivity ofthe capillary permeability is not affected in the peritoneal membrane inchildren with NS due to glomerulosclerosis and congenital nephroticsyndrome.