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Background: Transplant patients have an increased incidence of lymphoproliferative disorders. The development of a sensitive immunoassay for serum free light chain (sFLC) determination has improved the diagnosis of monoclonal gammapathy. However, metabolism of FLC largely depends on renal function which could lead to misinterpretation of results. The aim of this study was to assess polyclonal FLC in kidney transplant recipients in relation to markers of renal function., Materials and Methods: 97 renal transplant patients (median transplantation follow-up of 2.2 years) were included in this study. Kappa FLC, lambda FLC and cystatin C were measured by particle-enhanced turbidimetric immunoassay (PETIA) using kits from a Binding Site (Birmingham, UK) SPAPLUS(®) analyzer. Glomerular filtration rate was measured using urinary clearance of (99m)Tc-DTPA and estimated using CKD-EPI creatinine 2009, CKD-EPI cystatin C 2012 and CKD-EPI creatinine-cystatin C 2012., Results: Serum kappa FLC was 22.38 [6.39-68.91] mg/L and serum lambda FLC was 15.66 [7.29-50.81] mg/L. Both levels of kappa and lambda were correlated with renal function. Median κ/λ ratio was 1.34 [0.57 to 2.67] leaving 19.6% of renal transplant patients outside the normal reference range [0.26-1.65]. However, using a reference interval normalized by renal function [0.37-3.1], none of our patients was classified as abnormal., Conclusion: κ/λ ratio should be cautiously analyzed in renal transplantation and renal function, estimated by creatinine/cystatin C equations should be taken into account., (© 2013.)

Background: The potential use of cystatin C has recently emerged to evaluate kidney function following transplantation. Analytical performance of a particle-enhanced turbidimetric immunoassay (PETIA) using Dako Cytomation Cystatin C reagents on an Olympus AU640(®) analyzer was evaluated. Clinical relevance was determined by comparison with a reference method in a kidney transplant cohort., Methods: Repeatability and reproducibility were carried out for four levels of cystatin C. Linearity was done by successive dilution of plasma samples with high level of cystatin C. Comparison study was performed against the particle-enhanced nephelemetry immunoassay (PENIA) using Siemens reagents on BNII(®) system. Values of the glomerular filtration rate (GFR) estimated from several predictive cystatin C- and creatinine-based equations were compared to the GFR measured by isotopic method ((99m)Tc-DTPA). These predictive algorithms were analyzed with respect to bias, precision and accuracy., Results: Total intra-assay and inter-assay variation coefficients were below 4% at the four levels tested. Values obtained with Dako-PETIA on AU640(®) were correlated with the Siemens-PENIA method (Dako-Olympus=0.88 Siemens+0.17). The cystatin C alone and the creatinine-cystatin C combined equation allowed reliable assessment of GFR in our population of renal transplants. The cystatin C-based or the combined equation moderately improved determination of GFR (about 10% compared to 175MDRD for classification into the correct K/DOQI CKD stages)., Conclusions: The use of algorithms based on cystatin C and creatinine could provide a reliable estimate of the GFR in kidney transplantation. Standardization of cystatin C assays could further improve the predicting value of cystatin C in transplantation.

Background: The potential use of cystatin C was recently assessed in kidney transplantation. A new particle-enhanced turbidimetric immunoassay (PETIA) that uses sheep antibodies (Binding Site human cystatin C immunoassay) has been developed. Analytical performance of this new assay was evaluated. Clinical relevance was determined by comparison with a reference method in a cohort of kidney transplant patients., Methods: First, the analytical performance of the Binding Site cystatin C kit was tested on SPA(PLUS)® and Hitachi® analyzers. Second, a comparison study was performed using SPA(PLUS)® analyzer against two other cystatin C methods (the Siemens-PENIA method on BNII® and the Dako-PETIA application on Olympus AU640®). Third, the glomerular filtration rate (GFR) was estimated using several predictive cystatin C- and creatinine-based equations and compared to GFR measured by an isotopic method (⁹⁹(m)Tc-DTPA). These predictive algorithms were analyzed with respect to bias, precision and accuracy., Results: Total intra-assay and inter-assay coefficients of variation were below 5%. Values obtained with the SPA(PLUS)® correlated with the Siemens-PENIA and the Dako-PETIA methods. The creatinine and cystatin C-based equation allowed reliable assessment of GFR in our population of renal transplantation., Conclusions: The use of algorithms based on cystatin C and creatinine could provide a reliable estimate of GFR in kidney transplantation.

Background: New ID-MS traceable creatinine kits including enzymatic creatinine (e-creat) and compensated Jaffe (j-creat) has been developed by Olympus., Methods: Analytical performances of these reagents were tested on an AU 640 analyzer. A comparison study was performed against the method used in our laboratory (Randox creatinine enzymatic). Values of the glomerular filtration rate estimated (eGFR) from ID-MS traceable equation were compared to the GFR measured (mGFR) by a reference isotope method in a kidney transplant cohort., Results: Total intra- and inter-assay variation coefficients were below 4%. Creatinine values were correlated with the Randox enzymatic method (e-creat = 0.98 Randox - 0.48 and j-creat = 0.99 Randox - 1.44, r2 = 0.98). Values of eGFR obtained with both e-creat and j-creat were well correlated to mGFR in our population of renal transplants., Conclusions: The new ID-MS traceable methods improved estimation of GFR by predictive equations. However, the limitation of the Jaffe method in specific populations such as paediatric and elderly patients needs further investigations.

Background The estimated glomerular filtration rate (eGFR) measured at 1 year is the usual benchmark applied in kidney transplantation (KT). However, acting on earlier eGFR values could help in managing KT during the first post-operative year. We aimed to assess the prognostic value for long-term graft survival of the early (3 months) quantification of eGFR and proteinuria following KT. Methods The 3-, 6- and 12-month eGFR using the Modified Diet in Renal Disease equation (eGFRMDRD) was determined and proteinuria was measured in 754 patients who underwent their first KT between 2000 and 2010 (with a mean follow-up of 8.3 years) in our centre. Adjusted associations with graft survival were estimated using a multivariable Cox model. The predictive accuracy was estimated using the C-index and net reclassification index. These same analyses were measured in a multicentre validation cohort of 1936 patients. Results Both 3-month eGFRMDRD and proteinuria were independent predictors of return to dialysis (all P < 0.05) and there was a strong correlation between eGFR at 3 and 12 months (Spearman's ρ = 0.76). The predictive accuracy of the 3-month eGFR was within a similar range and did not differ significantly from the 12-month eGFR in either the derivation cohort [C-index 62.6 (range 57.2–68.1) versus 66.0 (range 60.1–71.9), P = 0.41] or the validation cohort [C-index 69.3 (range 66.4–72.1) versus 71.7 (range 68.7–74.6), P = 0.25]. Conclusion The 3-month eGFR was a valuable predictor of the long-term return to dialysis whose predictive accuracy was not significantly less than that of the 12-month eGFR in multicentre cohorts totalling >2500 patients. Three-month outcomes may be useful in randomized controlled trials targeting early therapeutic interventions. [ABSTRACT FROM AUTHOR]

Summary: Numerous studies have reported a weekend effect on outcomes for diseases treated at hospitals. No study has been conducted in France for kidney transplantation. We therefore performed a cohort‐based study to evaluate whether outcomes of kidney transplant recipients display a weekend effect. Data were extracted from the French DIVAT cohort. Patients aged 18 years and older, transplanted with a single kidney from deceased donors between 2005 and 2017 were studied. Linear regression, logistic regression, and cause‐specific Cox model were used. Among the 6652 studied patients, 4653 patients were transplanted during weekdays (69.9%) versus 1999 during weekends (30.1%). The only statistically significant difference was the percentage of patients with vascular surgical complication(s) at 30 days: 13.3% in the weekend group versus 16.2% in the weekday group 0.79 (95% CI: 0.68; 0.92). We did not observe other significant differences for the other outcomes: patient or graft survival, the risk of acute rejection episodes, the 30‐day percentage of urological complications, and the 1‐year estimated glomerular filtration rate. Our study highlights a small protective weekend effect with less post‐surgery vascular complications compared to weekdays. This paradox might be explained by a different handling of weekend transplantations. [ABSTRACT FROM AUTHOR]

Background: The potential use of cystatin C has recently emerged to evaluate kidney function following transplantation. Analytical performance of a particle-enhanced turbidimetric immunoassay (PETIA) using Dako Cytomation Cystatin C reagents on an Olympus AU640® analyzer was evaluated. Clinical relevance was determined by comparison with a reference method in a kidney transplant cohort. Methods: Repeatability and reproducibility were carried out for four levels of cystatin C. Linearity was done by successive dilution of plasma samples with high level of cystatin C. Comparison study was performed against the particle-enhanced nephelemetry immunoassay (PENIA) using Siemens reagents on BNII® system. Values of the glomerular filtration rate (GFR) estimated from several predictive cystatin C- and creatinine-based equations were compared to the GFR measured by isotopic method (99mTc-DTPA). These predictive algorithms were analyzed with respect to bias, precision and accuracy. Results: Total intra-assay and inter-assay variation coefficients were below 4% at the four levels tested. Values obtained with Dako-PETIA on AU640® were correlated with the Siemens-PENIA method (Dako-Olympus=0.88 Siemens+0.17). The cystatin C alone and the creatinine-cystatin C combined equation allowed reliable assessment of GFR in our population of renal transplants. The cystatin C-based or the combined equation moderately improved determination of GFR (about 10% compared to 175MDRD for classification into the correct K/DOQI CKD stages). Conclusions: The use of algorithms based on cystatin C and creatinine could provide a reliable estimate of the GFR in kidney transplantation. Standardization of cystatin C assays could further improve the predicting value of cystatin C in transplantation. [ABSTRACT FROM AUTHOR]