Accuracy and variability of equations to estimate glomerular filtration rates in renal transplant patients receiving sirolimus and/or calcineurin inhibitor immunosuppression*

Monitoring and managing graft health in the kidney transplant recipient

Ongoing monitoring of kidney transplants is a widely accepted and practiced part of posttransplantation management. One reason to monitor is to evaluate whether the transplant is stable. The transplant community evaluates stability by checking kidney function. Despite problems with sensitivity and specificity, obtaining serial serum creatinine levels is the most common approach to assessing kidney function. Some programs supplement serial serum creatinine levels with surveillance kidney biopsies. Although not uniformly accepted as beneficial, surveillance biopsies are useful in select subsets of patients such as highly sensitized recipients. Recent biopsy studies shed light on which histopathology findings portend poor prognoses. The Long-Term Deterioration of Kidney Allograft Function Study (DeKAF) and similar studies that will prospectively evaluate therapeutic interventions should help the transplant community better define how to monitor and manage the kidney transplant optimally. In the meantime, Kidney Diseases: Improving Global Outcomes (KDIGO) provides an evidence-based approach toward monitoring and managing the kidney transplant.

Evolution of glomerular filtration rate, renal injury markers, anemia, and angiotensin blockers use after change from calcineurin inhibitors to sirolimus in transplant patients with neoplasia versus chronic allograft nephropathy

BACKGROUND

The change from calcineurin inhibitors (CNI) to sirolimus (SRL) is a safe alternative in transplant patients with neoplasia (NEO) whereas the results of conversion for chronic allograft nephropathy (CAN) are controversial, depending on the histologic score, degree of proteinuria, and glomerular filtration rate (GFR). Our aim in this study was to compare GFR, proteinuria, albuminuria, blood pressure (BP) effects, and anemia after switching to sirolimus (SRL) among renal transplant recipients with CAN versus NEO.

METHODS

Fifty-five kidney transplant recipients with conversion from CNI to SRL owing to CAN or NEO were analyzed for the variables at 6 months before, at the time of, and at 6 months and 1, 2, and 3 years after the switch to SRL.

RESULTS

There were no differences between CAN and NEO in the slope of estimated GFR (mL/min/1.73 m(2) by Cockcroft-Gault formula) at 1 year (-5.5 vs 3.7; P = .007) and at 2 years (-3.86 vs -10.3; P = .01). The values of proteinuria (mg/24 h/1.73 m(2)) before (665 ± 136 vs 329 ± 69; P = .036) as well as at 1 (1,122 ± 306 vs 863 ± 190; P = .478) and at 2 years after conversion (1,360 ± 430 vs 457 ± 154; P = .045) showed some significant differences, as did the use of both antiangiotensin agents, angiotensin-converting enzyme inhibitor and angiotensin receptor blocker at the moment of switch (35% vs 0%; P = .005) at 1 year (69% vs. 6% P = .02) and at 2 years (67% vs 28%; P = .047). There were no differences in graft survival (log rank: P = .515). By logistic regression analysis, the best covariate associated with GFR >45 mL/min at 2 years was GFR >60 mL/min at the moment of switch to SRL (odds ratio, 1.33; 95% confidence interval, 1.002-1.74).

CONCLUSIONS

The evolution of renal damage was more important in the CAN group requiring greater use of 2 angiotensin antagonists for control of proteinuria. We probably need histologic and serologic biomarkers to show which patients with CAN will show a bad evolution after the change to SRL.

Validation of plasma clearance of 51Cr-EDTA in adult renal transplant recipients: comparison with inulin renal clearance

Plasma clearance of (51)Cr-EDTA ((51)Cr-EDTA-Cl) is an alternative method to evaluate glomerular filtration rate (GFR). This study aimed to investigate the concordance between (51)Cr-EDTA-Cl and renal inulin clearance (In-Cl) in renal transplant recipients as well to determine the repeatability of (51)Cr-EDTA-Cl in kidney donors. Forty four kidney recipients and 22 kidney donors were enrolled. Simultaneous measurements of (51)Cr-EDTA-Cl and In-Cl were performed. A single dose of 3.7MBq of (51)Cr-EDTA was injected and the plasma disappearance curve was created by taking blood samples at 2, 4, 6 and 8 h after injection. Bland and Altman statistical approach was used to quantify the agreement between In-Cl and (51)Cr-EDTA-Cl and to determine the better concordance between all possibilities of measure for the (51)Cr-EDTA-Cl. The mean of In-Cl was 44.5 +/- 17.9 ml/min/1.73 m(2). There was a positive correlation between In-Cl and all possible measurements of (51)Cr-EDTA-Cl. (51)Cr-EDTA-Cl with two samples taken at 4 and 8 h or at 4 and 6 h presenting the narrow limits of agreement and a difference (bias) of 2.8 and 2.7 ml/min, respectively. Two plasma sampling for (51)Cr-EDTA-Cl was a reliable method to measure GFR compared with In-Cl and comprises a suitable method to be used in kidney transplanted patients.