C. Bocci

Serum Beta-2-Microglobulin Level and Residual Renal Function in Peritoneal Dialysis

In 32 noncirrhotic patients on peritoneal dialysis, mean serum beta 2-microglobulin (s beta 2M) was 26.58 +/- 12.32 mg/l (9.7-63.5). We found a significant correlation between s beta 2M and serum creatinine (sCr; r = 0.760), blood urea nitrogen (BUN; r = 0.573), total creatinine and BUN clearance (r = 0.623 and 0.599, respectively), 24-hour Kt/V (r = 0.638), glomerular filtration rate (r = 0.623), 24-hour urine output (r = 0.669), serum total protein (r = 0.584) (p < 0.01 for all the above r values); beta 2M peritoneal clearance and mass transfer (r = 0.414 and 0.427, respectively; p < 0.05). Our data demonstrate and confirm the contribution of residual renal function in determining s beta 2M levels and it is seemingly more important than beta 2M peritoneal clearance.

Comparison of fast peritoneal equilibration tests with 1.36 and 3.86% dialysis solutions

At present dialysis solutions with different glucose concentrations are used for the peritoneal equilibration test (PET) and Fast-PET in peritoneal dialysis (PD). We compared the results of two Fast-PETs, using 1.36 and 3.86% solutions sequentially in 30 patients on PD treatment, to obtain information on peritoneal transport (D/P-4 h) and ultrafiltration rates. Creatinine, phosphorus and urea D/P-4 h in the two Fast-PETs were not statistically different, unlike those for potassium, beta 2-microglobulin and glucose. The creatinine and phosphorus D/P-4 h values in particular proved to be uninfluenced by the different dialysis solutions. The lack of correlation between the two Fast-PET ultrafiltration values confirmed the difficulty in interpreting this parameter, above all in the case of non-homologous Fast-PETs. We obtained useful indications for comparing different Fast-PET results, but were unable to reach a decisive conclusion regarding the best of the two dialysis solutions for this test.

Correction of glucose concentration interference on Jaffé kinetic creatinine assay in peritoneal dialysis

Overestimation of creatinine measurement using the Jaffé kinetic method in peritoneal dialysis solutions, due to glucose interference, has been quantified and corrected through the elaboration of linear formulas obtained from 110 recovery and 301 biological tests. The added pure powdered creatinine and enzymatic method were considered as references after proven accuracy. Considering creatinine as well as glucose concentration interference, we obtained correction formulas from multiple regression application. All the computed formulas gave satisfactory corrections but different accuracy levels. The best model in biological samples was: Corrected CR = K1JafféCr + K2Glucose (all values in mg/dl) where K1 = 0.973 and K2 = -0.00035 (Rsq = 0.987, F ratio = 10,945, p = 0.00001). Applying formulas to biological samples there was a drop in accuracy, possibly explained by the presence of numerous unidentified substances in peritoneal dialysis biological samples that can amplify scatter. Every laboratory can reduce the error of the Jaffé kinetic assay by calculating their own correction formula in relation to the method and instrument used, because Jaffé kinetic assay gives different results with different kinetic windows. So, especially when applied to peritoneal dialysis fluid measurements, if a creatinine assay reference method is not available, the correction formula can be applied directly as given. Otherwise the method we have described can be followed with a well-structured creatinine recovery fest to identify and quantify assay interferences.

Verticillium Peritonitis in a Patient on Peritoneal Dialysis

We describe a case of peritonitis due to Verticillium spp. in a 33-year-old farmer on continuous ambulatory peritoneal dialysis (CAPD) for 3 months for end-stage renal failure due to chronic pyelonephritis. The etiologic agent was a hyaline hyphomycete which we report as a new human opportunistic pathogen. The fungus was isolated from the peritoneal fluid culture and from the tip of the catheter; identification was made on the basis of macroscopic and microscopic features. The patient had previously been admitted to our hospital for peritonitis caused by mixed enteric flora and treated for 8 days with intraperitoneal broad-spectrum antibiotic therapy. Five days after discharge he was readmitted for severe abdominal pain and cloudy drainage fluid. Two days of intraperitoneal broad-spectrum antimicrobial therapy produced no clinical improvement. Intravenous fluconazole and oral flucytosine were administered upon identifying the fungus. After another 2 days without improvement, peritoneal dialysis was discontinued and the catheter removed. Antimycotic therapy was continued for 4 days with complete resolution of the peritonitis. The patient chose to start hemodialysis and was discharged in good clinical condition.