Plasma creatinine medians from patients partitioned by gender and age used as a tool for assessment of analytical stability at different concentrations

Background Monthly medians of patient results are useful in assessment of analytical quality in medical laboratories. Separate medians by gender makes it possible to generate two independent estimates of contemporaneous errors. However, for plasma creatinine, reference intervals (RIs) are different by gender and also higher over 70 years of age. Methods Daily, weekly and monthly patient medians were calculated from the raw data of plasma creatinine concentrations for males between 18 and 70 years, males >70 years, females between 18 and 70 years and females >70 years. Results The medians of the four groups were all closely associated, with similar patterns. The mean of percentage bias from each group defined the best estimate of bias. The maximum half-range (%) of the bias evaluations provided an estimate of the uncertainty comparable to the analytical performance specifications: thus, bias estimates could be classified as optimum, desirable or minimum quality. Conclusions Medians by gender and age are useful in assessment of analytical stability for plasma creatinine concentration ranging from 60 to 90 μmol/L. The daily medians are valuable in rapid detection of large systematic errors, the weekly medians in detecting minor systematic errors and monthly medians in assessment of long-term analytical stability.

PSVII-16 Dietary creatine and sulfur amino acids for finishing gilts

The objective of this study was to evaluate the effects of dietary creatine and SID methionine+cysteine (Met+Cys) levels on the performance, blood parameters and gene expression of the creatine transporter (SLC6A8) in finishing gilts. Forty gilts, averaging 75.26 ± 0.87 kg of initial weight, were distributed in a randomized blocks design in a 2x2 factorial scheme, consisting of two creatine monohydrate (CMH) supplementation levels (0.00 and 0.10%) and two levels of SID Met+Cys (0.40 and 0.44%, considering 0.44% as the requirement), with 10 replicates. DL methionine was used to ensure the dietary SID Met+Cys levels. Upon reaching a mean weight of 100± 5.85, blood was collected for the determination of urea, creatinine, lactate, glucose and homocysteine plasma concentrations. Afterwards, the gilts were slaughtered for the collection of Longissimus dorsi muscle samples, for further determination of the gene expression of the creatine transporter (SLC6A8). No interactions (P > 0.05) we observed between the CMH and SID Met+Cys on the performance and gene expression of the SLC6A8 transporter, and also were not affected (P > 0.05) by the dietary levels of CMH or SID Met+Cys, individually. However, there was an interaction (P = 0.03) between SID Met+Cys and CMH levels on the plasma creatinine concentration, showing a lower (P = 0.018) concentration (6.40 mg/dL) supplementing 0.10% CMH than not supplementing (8.96 mg/dL), only at 0.44% of SID Met+Cys. There were no interactions (P > 0.05) between SID Met+Cys and CMH on the other blood parameters, and also no individual effects were observed for the studied factors. It is concluded that supplementing 0.10% CMH reduced plasma creatinine concentration only at conventionally dietary SID Met+Cys level (0.44%), not affecting other blood parameters, growth performance and the gene expression of the creatine transporter SLC6A8 of finishing gilts.

Iohexol Plasma Clearance in Animal Models: The Clear Choice for Measuring Early Renal Dysfunctio

Glomerular filtration rate is a measure of the kidney’s ability to filter blood. In animal models of early kidney failure, there is no routine method to accurately measure GFR. The expensive gold standard of GFR measurement is exogenous inulin clearance. The commonly used method, endogenous plasma creatinine concentration, is unreliable and insensitive, especially at normal levels of renal function. This study investigates the utility of iohexol, an inexpensive radio-contrast agent as a promising exogenous marker for plasma clearance kidney function evaluation in rats. Early stages of progressive kidney failure were induced with a 0.25% adenine diet in male Sprague Dawley rats (N=8) over 5 weeks. Both plasma clearance of iohexol and inulin and creatinine concentration were evaluated following weekly venous injections and blood sampling. Plasma iohexol clearance and plasma inulin clearance strongly correlate (R2=0.95). However, plasma creatinine concentration correlated weakly with iohexol(R2=0.53) and inulin(R2=0.58). Iohexol plasma clearance accurately measures changes in kidney function, especially in in comparison to creatinine analysis. The data demonstrates creatinine is an inappropriate marker for renal function in early adenine-induced CKD rat models. Ongoing analysis of this data suggests refinement of the protocol will yield a simple method for routine measure of kidney function in murine lab animals. This tool will facilitate advancement in kidney disease onset and allow for more accurate interpretation of kidney function in the various animal models.

Repeated measurements of renal function in evaluating its decline in cats

Objectives The aim of this study was to describe the variability in renal function markers in non-azotaemic and azotaemic cats, and also the rate of change in the markers. Methods Plasma creatinine concentration and its reciprocal, glomerular filtration rate (GFR) and urine specific gravity (USG) were studied as markers of renal function in client-owned cats. GFR was determined using a corrected slope-intercept iohexol clearance method. Renal function testing was performed at baseline and a second time point. The within-population variability (coefficient of variation; CV%) was determined at the baseline time point. Within-individual variability (CV%) and rate of change over time were determined from the repeated measurements. Results Twenty-nine cats were included in the study, of which five had azotaemic chronic kidney disease. The within-individual variability (CV%) in creatinine concentration was lower in azotaemic cats than in non-azotaemic cats (6.81% vs 8.82%), whereas the within-individual variability in GFR was higher in azotaemic cats (28.94% vs 19.98%). The within-population variability was greatest for USG (67.86% in azotaemic cats and 38.00% in non-azotaemic cats). There was a negative rate of change in creatinine concentration in azotaemic and non-azotaemic cats (–0.0265 and –0.0344 µmol/l/day, respectively) and a positive rate of change of GFR in azotaemic and non-azotaemic cats (0.0062 and 0.0028 ml/min/day, respectively). Conclusions and relevance The within-individual variability data suggest creatinine concentration to be the more useful marker for serial monitoring of renal function in azotaemic cats. In contrast, in non-azotaemic cats, GFR is a more useful marker for serial monitoring of renal function. The majority of cats with azotaemic CKD did not have an appreciable decline in renal function during the study.

Clinical Course and Outcomes of Late Kidney Allograft Dysfunction

Background.This study is provided to increase the efficiency of the treatment of kidney transplant recipients by predicting the development of the late allotransplant dysfunction.Methods. 330 patients who have lived for more than one year with functioning kidney allograft were evaluated. To predict the subsequent duration of the well-functioning of allotransplant the prognostic significance of 15 baseline clinical and sociodemographic characteristics on the results of the survey one year after transplantation was investigated. The result was considered to be positive in constructing the regression prognostication model if recipient lived more than 3 years from the time of transplantation.Results. It was established that more late start of renal allograft dysfunction after transplantation correlates with the more time it takes till complete loss of allograft function. Creatinine and hemoglobin blood concentration and the level of proteinuria one year after transplantation within created mathematical model allow predicting the loss of kidney transplant function three years after the transplantation. Patients with kidney transplant dysfunction are advised to renew the program hemodialysis upon reaching plasma creatinine concentration 0.5–0.7 mmol/L.Conclusion. Values of creatinine, hemoglobin, and proteinuria one year after transplantation can be used for subsequent prognostication of kidney transplant function.

Relation between MicroRNA Expression in Peritoneal Dialysis Effluent and Peritoneal Transport Characteristics

Background:The role of microRNAs (miRNAs) in peritoneal transport is uncertain.Methods:We studied 82 new peritoneal dialysis (PD) patients, 22 prevalent patients without ultrafiltration problem, and 6 patients with documented ultrafiltration problem. Peritoneal transport was determined by standard peritoneal equilibration test (PET). RNA was extracted from the PD effluent after PET, and intra-peritoneal expression of miRNA targets were quantified.Results:There were significant difference in the PDE expressions of miR-15a and miR-21. There were modest inverse correlations between ultrafiltration volume and PDE expression of miR-17 (r= −0.198,p= 0.041) and miR-377 (r= −0.201,p= 0.041). There was an inverse correlations between dialysate-to-plasma creatinine concentration at 4 hours and PDE expression of miR-192 (r= −0.199,p= 0.040); while mass transfer area coefficient of creatinine correlated with PDE expression of miR-192 (r= −0.191,p= 0.049) and miR-377 (r= 0.201,p= 0.041). Amongst 7 randomly selected patients who had repeat PET after one year, there was a significant correlation between baseline PDE expression of miR-377 and change in ultrafiltration volume (r= −0.852,p= 0.015).Conclusion:The miRNA expression in PDE, including miR-15a, miR-17, miR-21, miR-30, miR-192, and miR-377, correlated with peritoneal transport characteristics. Our result suggests that miRNA may play a role in the regulation of peritoneal membrane function.