Abstract
We have developed a charge selectivity index (CSI) for estimating the indicator of peritoneal function. The calculation formula is as follows: [CSI {glutamate (Glu)/glutamine (Gln)}: Glu D/P ratio÷Gln D/P ratio, CSI {lysine (Lys)/glutamine (Gln)}: Lys D/P ratio÷Gln D/P ratio].
Furthermore, we determined the CSI by using neutral IgG1 and acid IgG4, which had different isoelectric points despite their equal molecular weight. The formula of this measurement is as follow: [CSI (IgG4/IgG1): IgG4 D/P ratio÷IgG1 D/P ratio]. The CSI was determined in two groups. One was a group of 50 outpatients who had been enrolled in this study, in whom no episode of peritonitis was recognized within a year prior to the study (normal group). The other was a group of 16 patients who had an episode of peritonitis within the previous month (peritonitis group). Following the standard peritoneal equilibration test (PET), 2 liters of a 2.5% glucose dialysate was injected into and held in the peritoneal cavity for exactly 4 hours. Dialysate samples were collected at 0 and 4 hours. A single serum sample was obtained at the midpoint of the procedure. Peritoneal transport was estimated from the dialysate (D) to plasma (P) ratio of amino acid (Glu, Gln, Lys), IgG1, IgG4, creatinine (Cr), β2-microglobulin (β2-MG), and albumin (Alb) at 4 hours. The D/D0 glucose ratio was calculated, and then each CSI was calculated.
The results of the study were as follows: (1) D/P ratios of Glu, Gln, Lys, IgG1, IgG4, Cr, β2-MG and Alb were significantly increased in the peritonitis group. (2) CSI (Glu/Gln), CSI (Lys/Gln), and CSI (IgG4/IgG1) were significantly increased in the peritonitis group. (3) A significant correlation was obtained between the CSI (Glu/Gln) and D/D0 glucose ratios, CSI (IgG4/IgG1) and D/P ratios of Alb. (4) A significant correlation was obtained between CSI (IgG4/IgG1) and CSI (Glu/Gln), or CSI (Lys/Gln). (5) A significant correlation was obtained between CSI (Glu/Gln), CSI (Lys/Gln), CSI (IgG4/IgG1), D/P ratios of Giu, D/P ratios of Cr, D/D0 glucose ratios, and dialysis duration among the normal group.
Those CSI's indicated a new test to estimate peritoneal membrane function.
