PERITONEAL PROTEIN LOSS IN CHILDREN WITH NEPHROTIC SYNDROME DURING PERITONEAL-DIALYSIS

Background. The passage of proteins across the glomerular filtration b arrier is mainly determined by the size of the protein. In nephrotic s yndrome (NS) the glomerular permselectivity is affected, causing prote inuria. Some authors suggest the existence of a generalized basement m embrane defect. The permeability characteristics of the peritoneal bas ement membrane in children with NS are not known. Methods. The transpe ritoneal transport of proteins with a different molecular weight (beta (2)-microelobulin MW 11 800 D, albumin MW 69 000 D, IgG MW 160 000 D, and alpha(2)-macroglobulin MW 820 000 D) was studied in a study group (group A) consisting of six stable nephrotic children (three with glom erulosclerosis and three with congenital nephrotic syndrome, one of th em with mesangial sclerosis) and compared to a control group (group B) consisting of eight stable children on peritoneal dialysis. After a d well of 6 h with Dianeal 1.36% dialysate and serum samples were collec ted. For each patient the dialysate to plasma (D/P) ratios of the four proteins were calculated. The D/P ratios of the nephrotic patients in group A were compared to the D/P ratios of the patients in the contro l group B. Data were expressed as mean +/- SD. Results. The values for the D/P ratios tin percentage) of beta(2)-microglobulin, albumin, IgG and alpha(2)-macroglobulin in group 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 the control group B. The ratios were plotted against MW on a double logarithmic scale. In all patients a li near relationship between molecular weight and D/P ratio of the protei ns was obtained. The D/P ratios of the study group did not differ sign ificantly from the control group.Conclusion. We conclude that the size selectivity of the capillary permeability is not affected in the peri toneal membrane in children with NS due to glomerulosclerosis and cong enital nephrotic syndrome.