Platelet thrombus formation in patients with end-stage renal disease before and after hemodialysis as measured by the total thrombus-formation analysis system.

BACKGROUND: Patients with end-stage renal disease (ESRD) receiving hemodialysis (HD) often experience bleeding. However, mechanisms behind this bleeding tendency are incompletely understood but may involve platelet dysfunction. We, therefore, studied platelet-dependent thrombus formation in flowing whole blood inside a microchip coated with collagen, and its association with circulating von Willebrand factor (VWF). METHODS: Blood samples were obtained in 22 patients before and after HD. The area under the 10 min flow pressure curve in a microchip (AUC10) reflecting total platelet thrombogenicity was measured, using the Total Thrombus-formation Analysis System (T-TAS01). AUC10 < 260 indicates platelet dysfunction. VWF activity and antigen in plasma were also assayed. RESULTS: VWF levels were moderately elevated and increased further after HD (P < 0.01 or lower). In contrast, AUC10 before and after HD was < 260 in 17/22 patients and < 130 in 15/22 patients, with no statistically significant difference in pre- vs post-HD measurements, indicating reduced platelet thrombogenicity, but with some variability as 5/22 patients showed normal platelet responsiveness. AUC10 and VWF activity or antigen levels in plasma were not correlated, either before or after HD. CONCLUSIONS: Most ESRD patients display moderate-to-severe platelet dysfunction as assessed by shear-induced platelet-dependent thrombus formation with T-TAS01. HD does not influence platelet function despite HD-induced elevations in VWF. T-TAS01 should be further evaluated as a tool in the assessment of bleeding risk in patients on HD.

Combined Effect of Inter- and Intrapatient Variability in Tacrolimus Exposure on Graft Impairment Within a 3-Year Period Following Kidney Transplantation: A Single-Center Experience.

BACKGROUND AND OBJECTIVE: Tacrolimus is a cornerstone of the most immunosuppressive protocols after kidney transplantation, but its use is complicated by notable interpatient and intrapatient variability (IPV). The goal of this study was to evaluate whether or not tacrolimus IPV, or average dose-adjusted trough concentration (C0/D), during 6-12 months post-transplantation might have contributed to graft function decline in a 3-year period following kidney transplantation. After primary evaluation of individual effects of tacrolimus IPV and C0/D, the study aimed to estimate the combined effect of tacrolimus IPV and C0/D on composite endpoint (consisting of graft failure, chronic allograft dysfunction, chronic rejection, and doubling of serum creatinine concentration) in the period between 13 and 36 months after kidney transplantation. In addition, the goal was to analyze the impact of genetics on interpatient variability in tacrolimus exposure in the early and late post-transplantation periods. METHODS: The study enrolled 104 Caucasian patients and included 2541 patient examinations up to 36 months after kidney transplantation. All patients were genotyped on CYP3A5 6986A>G and ABCB1 3435C>T gene polymorphism. Patients were divided into groups based on the tacrolimus IPV tertiles and the median value of average C0/D during 6-12 months post-transplantation. RESULTS: The results showed a more pronounced decline in estimated glomerular filtration rate values within the high IPV tertile group (p = 0.018), as well as within the low C0/D group (p = 0.013) in a 3-year period after kidney transplantation. The carriers of CYP3A5*1/*3 genotype had lower C0/D compared to the CYP3A5*3/*3 carriers during the entire study period, while the results for ABCB1 were inconsistent when considering tacrolimus C0/D. Patients with high IPV/low C0/D had significantly reduced graft survival compared to the other tacrolimus IPV/C0/D combination groups (i.e., high IPV/high C0/D, low IPV/low C0/D, low IPV/high C0/D) with the hazard ratio of 3.14 in Cox analysis for reaching the composite endpoint. CONCLUSION: The findings of this study suggest that combined assessment of tacrolimus IPV and tacrolimus C0/D may categorize patients towards risk of graft deterioration in the long-term post-transplantation period.

Elevated Serum Ferritin Levels Are Predictive of Renal Function Recovery among Patients with Acute Kidney Injury.

Oxidative stress (OS) frequently contributes to the development of acute kidney injury (AKI). Iron can promote oxidative stress and tissue injury by catalyzing free reactive oxygen species (ROS) generation and increasing the steady-state concentration of these potent oxidants. The anticipated role of ferritin is to protect from OS by sequestering iron and limiting its involvement in reactions that generate ROS. In this prospective study, we aimed to investigate the association between serum ferritin levels and kidney function recovery among patients with AKI. Renal recovery was determined as a return of serum creatinine to less than 1.25 times the baseline value after 90 days of follow-up. One hundred twelve patients (72 males and 40 females, 63.68 ± 10.6 years old) were included in the final analysis. They were divided into AKI recovery (n = 76) and non-recovery groups (n = 36). Ferritin levels on admission were higher in AKI recovery group [284 (IQR 153-525) ng/mL] compared with the non-recovery group [127.4 (IQR 30-243) ng/mL], p < 0.001. Serum ferritin levels and the renal recovery significantly positively correlated (r = 0.72, p < 0.001). In multiple linear regression analysis, higher serum ferritin was associated with renal function recovery (OR 3.68, CI 2.02-3.97, p < 0.001). The optimal cut-off point of 240.5 ng/mL was determined for serum ferritin, which showed a sensitivity of 75.8% and a positive predictive value of 90%. In conclusion, serum ferritin levels on admission may be used as a prognostic marker for predicting renal recovery in AKI patients.