Comparison between creatinine-based equations for estimating total creatinine clearance in peritoneal dialysis: a multicentre study.

BACKGROUND: It is crucial to assess the adequacy of peritoneal dialysis (PD) because of its influence on patient outcome. Collecting dialysate and urine for 24 h can be rather troublesome, so a simple and inexpensive alternative method for rapidly evaluating adequacy in PD would be very useful. Our study aimed to assess the performance of 12 different creatinine (Cr)-based equations commonly used to estimate GFR in predicting total Cr clearance (totCrCL) in PD. METHODS: Four Italian dialysis centres enrolled 355 PD patients with 2916 fluid collections. To rank the equations, their accuracy (median absolute percentage error, MAPE), precision (root mean square error, RMSE), agreement (k statistics), sensitivity and specificity (area under ROC curves, AUC, where x = 1 - specificity and y = sensitivity) were calculated with reference to the measured totCrCL. RESULTS: The Gates, Virga and 4-MDRD equations showed the best global performance as concerns accuracy (MAPE = 14.1, 16.3, 15.9% respectively), precision (RMSE = 13.2, 13.3, 13.4), agreement (k = 0.425, 0.440, 0.375), sensitivity and specificity (AUC = 0.825, 0.826, 0.820), while the Cockcroft-Gault formula revealed a rather poor reliability. CONCLUSIONS: Fluid collection remains the gold standard for assessing PD adequacy. Our study ascertained how 12 Cr-based equations performed in estimating totCrCL in PD patients with a view to enabling the most accurate and precise among them to be chosen for use in approximately assessing totCrCL.

A new equation for estimating renal function using age, body weight and serum creatinine.

BACKGROUND: Many formulas have been developed to estimate glomerular filtration rate (GFR). The aim of our study was to propose a new, more reliable equation. METHODS: The study considered 530 subjects (training sample) with M/F 280/250, age 57.1 +/- 17.4, creatinine clearance (CrCl) 55.2 +/- 38.2 (range 2.1-144.0) for the development the new equation. A linear model was used to describe Cr production using serum Cr (sCr), age, and body weight (BW) as variables: (CrCl + b(4)) . sCr = b(1) - (b(2) . age) + (b(3) . BW) subsequently estimating parameter values by linear least squares, with CrCl as the dependent variable, and 1/sCr, age/sCr, BW/sCr as independent variables. CrCl = {[69.4 - (0.59 . age) + (0.79 . BW)]/sCr} - 3.0 (males) and {[57.3 - (0.37 . age) + (0.51 . BW)]/sCr} - 2.9 (females). A 229-patient renal failure validation sample with M/F 166/63, age 53.0 +/- 14.8, GFR 32.0 +/- 14.3 (range 4.3-69.8), assessed using iohexol Cl, was considered to compare the Cockcroft-Gault (C-G) and MDRD formulas with the new equation for estimating GFR. RESULTS: The mean % error in GFR estimated by the new equation (+2.3 +/- 28.3%) was better than with the C-G and MDRD formulas (+5.2 +/- 30.1% and -11.4 +/- 25.9%, respectively, p < 0.0005 and p < 0.0001), and so was the mean absolute % error, bordering on statistical significance (19.8 +/- 20.3 vs. 21.1 +/- 22.0 and 22.4 +/- 17.3, p = 0.08 and p < 0.005). The precision was also better (RMSE = 7.89 vs. 8.02 and 9.13). The Bland-Altman test showed no GFR over or underestimation trend (measured +/- predicted GFR/2 vs. % error, R2 = 0.001). CONCLUSIONS: The new equation appears to be at least as accurate as the C-G and MDRD formulas for estimating GFR.

Phenotypic and genetic heterogeneity in Dent's disease--the results of an Italian collaborative study.

BACKGROUND: Dent's disease is an inherited tubulopathy caused by CLCN5 gene mutations. While a typical phenotype characterized by low-molecular-weight (LMW) proteinuria, hypercalciuria, nephrocalcinosis, nephrolithiasis, rickets and progressive renal failure in various combinations often enables a clinical diagnosis, less severe sub-clinical cases may go under-diagnosed. METHODS: By single-strand conformation polymorphism analysis and direct sequencing, we screened 40 male patients from 40 unrelated families for CLCN5 gene mutations. Twenty-four of these patients had the prominent features of Dent's disease, including LMW proteinuria, hypercalciuria and nephrocalcinosis. RESULTS: We identified 24 mutations in the CLCN5 gene in 21/24 patients with a typical phenotype and in 3/16 patients with a partial clinical picture of Dent's disease. Overall, 10 novel CLCN5 mutations were identified (E6fsX11, W58fsX97, 267 del E, Y272C, N340K, F444fsX448, W547X, Q600X, IVS3 +2 G>C and IVS3 -1 G>A), extending the number of mutations identified so far from 75 to 85. The CLCN5 coding sequence was normal in three patients. In the group with an incomplete Dent's disease phenotype, we detected two intronic mutations and one silent substitution leading to the up regulation of an alternatively spliced isoform. CONCLUSIONS: Our data confirm the genetic heterogeneity of Dent's disease. In most classic cases, the clinical diagnosis is confirmed by genetic tests.

Systolic and diastolic function in renal replacement therapy: a cross-sectional study.

BACKGROUND: Heart disease is the main cause of death among uremic patients (pts). Our study aimed to assess left ventricular (LV) systolic and diastolic function in all of our pts on renal replacement therapy (RRT), investigating any differences between hemodialysis (HD), peritoneal dialysis (PD) and transplantation (TX) pts. METHODS: All pts on RRT at our nephrology unit were enrolled in the study and evaluated once over a period of 6 months: 125 pts were studied: 61 pts on HD, 30 pts on PD and 34 TX pts. Systolic and diastolic function indexes were compared between HD, PD and TX pts. All comparisons were corrected for the effects of age, gender and time on treatment. RESULTS: HD pts suffered from worse systolic function, with a lower mean fractional shortening and ejection fraction (EF), than TX pts. Twenty percent of HD pts had an EF value <55%. PD pts showed worse diastolic function than TX pts and >80% of them suffered from pathological diastolic indexes. The proportion of hypertensive pts was TX 88.2%, PD 86.7% and HD 50.8%. The percentage of pts with LV hypertrophy (LVH) was TX 55.9%, PD 53.3% and HD 36.1%. CONCLUSIONS: TX pts had better systolic and diastolic function than HD and PD pts, despite having more hypertension and LVH.

Aspergillus fumigatus peritonitis in ambulatory peritoneal dialysis: a case report and notes on the therapeutic approach.

Aspergillus peritonitis is a rare disease in continuous peritoneal dialysis. It is a severe form of peritonitis, which is frequently lethal. We report a case of Aspergillus fumigatus peritonitis in a female patient on automated peritoneal dialysis (APD), who was successfully treated with intravenous amphotericin B and the removal of the peritoneal catheter. As delayed treatment has an increased mortality rate, it is mandatory to remove the catheter and to start intravenous treatment with amphotericin B empirically.

Comparison of peritoneal equilibration test with 2.27% and 3.86% glucose dialysis solution.

BACKGROUND: The standard Peritoneal Equilibration Test (PET) uses a 2.27% glucose dialysis solution in peritoneal dialysis (PD). A more hypertonic solution (3.86%) has recently been proposed to obtain further information about ultrafiltration (UF). AIM: To compare results in terms of peritoneal solute transport (4h-dialysate-to-plasma ratio, 4h-D/P) between 2.27% and 3.86% PET. DESIGN: 23 patients on PD were randomized to form two groups, A and B. A 2.27% dextrose 2-L exchange was used in group A, followed on the same day by a 3.86% dextrose 2-L exchange, both with a 4-hour dwell (2.27% and 3.86% PET); in group B, the same treatment was administered in reverse. 4h-D/P of urea, creatinine and sodium at time 0, 60, 120 and 240 minutes and net UF were calculated for each PET and compared. RESULTS: No significant statistical differences were found for the usual peritoneal transport indexes, 4h-D/P of urea and creatinine, between 2.27% and 3.86% PET, which produced almost identical results. The creatinine 4h-D/P were 0.67+/-0.09 vs. 0.66+/-0.10 (p= NS) and the urea 4h-D/P 0.91+/-0.04 vs. 0.90+/-0.04 (p= NS). The sodium D/P was lower at all times during the 3.86% PET: D/P60= 0.92+/-0.05 vs. 0.88+/-0.03, D/P120= 0.91+/-0.02 vs. 0.87+/-0.03, D/P240= 0.92+/-0.02 vs. 0.88+/-0.04 (p< 0.0001). The net UF was 478 +/- 175 vs. 936 +/- 233 mL respectively (p< 0.0001). CONCLUSION: Our study suggests that a 3.86% PD solution could be used for PET instead of the 2.27% solution in order to assess peritoneal solute transport, as well as UF, while obtaining almost identical results as the 2.27% solution.