Estimating glomerular filtration rate at the transition from pediatric to adult care

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Prediction of Renal Function After Living Donor Kidney Transplantation

There is no reliable method to predict the ideal expected function after a kidney transplantation. Herein we have described our experience in the living donor kidney transplant setting, comparing donor and recipient renal function (body surface area adjusted) before the LDKT, and during six months after this procedure. We determined the expected relation between donor and recipient renal function as well as its evolution over time.     

Comparing GFR Estimating Equations Using Cystatin C and Creatinine in Elderly Individuals

Current guidelines recommend reporting eGFR using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations unless other equations are more accurate, and recommend the combination of creatinine and cystatin C (eGFRcr-cys) as more accurate than either eGFRcr or eGFRcys alone. However, preferred equations and filtration markers in elderly individuals are debated. In 805 adults enrolled in the community-based Age, Gene/Environment Susceptibility (AGES)-Reykjavik Study, we measured GFR (mGFR) using plasma clearance of iohexol, standardized creatinine and cystatin C, and eGFR using the CKD-EPI, Japanese, Berlin Initiative Study (BIS), and Caucasian and Asian pediatric and adult subjects (CAPA) equations. We evaluated equation performance using bias, precision, and two measures of accuracy. We first compared the Japanese, BIS, and CAPA equations with the CKD-EPI equations to determine the preferred equations, and then compared eGFRcr and eGFRcys with eGFRcr-cys using the preferred equations. Mean (SD) age was 80.3 (4.0) years. Median (25th, 75th) mGFR was 64 (52, 73) ml/min per 1.73 m², and the prevalence of decreased GFR was 39% (95% confidence interval, 35.8 to 42.5). Among 24 comparisons with the other equations, CKD-EPI equations performed better in 9, similar in 13, and worse in 2. Using the CKD-EPI equations, eGFRcr-cys performed better than eGFRcr in four metrics, better than eGFRcys in two metrics, and similar to eGFRcys in two metrics. In conclusion, neither the Japanese, BIS, nor CAPA equations were superior to the CKD-EPI equations in this cohort of community-dwelling elderly individuals. Using the CKD-EPI equations, eGFRcr-cys performed better than eGFRcr or eGFRcys.     

The Clinical Impact of an Early Decline in Kidney Function in Patients Following Heart Transplantation

Renal dysfunction is a well-known complication following heart transplantation. We examined an early decline in kidney function as a predictor of progression to end-stage renal disease and mortality in heart transplant recipients. We performed a retrospective cohort study of 233 patients who received a heart transplant between July 1985 and July 2004, and who survived >1 month. The decline in estimated creatinine clearance (CrCl) was used to predict the outcomes of need for chronic dialysis or mortality >1-year posttransplant. The earliest time to chronic dialysis was 484 days. A 30% decline in CrCl between 1 month and 12 months predicted the need for chronic dialysis (p = 0.01), all-cause mortality (p < 0.0001) and time to first CrCl ≤30 mL/min at >1-year posttransplant (p = 0.02). A 30% decline in CrCl between 1 month and 3 months also independently predicted the need for chronic dialysis (p = 0.04) and time to first CrCl ≤ 30 mL/min at >1-year posttransplant (p = 0.01). In conclusion, an early drop in CrCl within the first year is a strong predictor of chronic dialysis and death >1-year postheart transplantation. Future studies should focus on kidney function preservation in those identified at high risk for progression to end-stage kidney disease and mortality.     

Factors Associated with Hyperhomocysteinemia After Renal Transplantation

Recent studies show that clinically stable renal transplant recipients have an increased prevalence of hyperhomocysteinemia (hyperHcy), but the mechanism of this disorder has not yet been elucidated. The aim of the present study was to evaluate the factors associated with hyperHcy after a successful renal transplantation. In 106 stable renal transplant recipients, total serum Hcy level (tHcy), folate, total protein, serum creatinine concentration, creatinine clearance, lipid status, body weight (BW), body mass index (BMI), and body fat (BF) were determined. The mean doses of cyclosporine, prednisolone, and azathioprine (mg/kg/day) were recorded. The mean serum tHcy level was significantly higher in renal transplant patients than in healthy controls (22.02 ± 8.02 versus 13.0 ± 3.3 μmol/L; p < 0.001), and the incidence of patients with hyperHcy was 82%. Comparison of the group of 20 patients with tHcy level <15 μmol/L and the group of 86 patients with tHcy level >15 μmol/L revealed that the latter was significantly older, heavier, had been longer on dialysis before renal transplantation, and had older donors and poorer renal graft function. Significant correlation was found between tHcy level and recipient age, dialysis duration, BW, creatinine clearance, serum creatinine, and folate concentration. However, multivariate analysis indicated that creatinine clearance (p = 0.025) and BW (p = 0.03) were the only determinants of elevated total Hcy level in renal transplant recipients. HyperHcy persists after successful kidney transplantation in the majority of renal transplant recipients, and its appearance is primarily associated with creatinine clearance and body weight.     

The Performance of Three Serum Creatinine-Based Formulas in Estimating GFR in Former Kidney Donors

Studies addressing long-term consequences of living with one kidney have used serum creatinine-based formulas that have not been validated in former kidney donors. Therefore, we evaluated the performance of Cockcroft-Gault (CG), Modification of Diet in Renal Disease (MDRD) and Mayo Clinic formulas in predicting iohexol glomerular filtration rate (iGFR) after donation in 112 randomly selected former kidney donors. Mean time from donation was 12.2 +/- 8.5 years. Serum creatinine was 1.1 +/- 0.2 mg/dL and iohexol GFR was 72 +/- 12 mL/min/1.73 m(2). The majority, 83.9%, of donors had a GFR >60 mL/min. CG formula overestimated GFR by 3.35 +/- 13.6 mL/min and was within 10% of iohexol GFR in only 43.7% of cases. MDRD formula underestimated iohexol GFR by 6.45 +/- 9.5 mL/min and was within 10% of actual GFR in half of the cases. In contrast, the Mayo Clinic equation was the most biased at 14.71 +/- 12.3 mL/min and was within 10% of measured GFR in only a fifth of the cases. Only MDRD and CG formulas provide estimates of GFR in former kidney donors that are within a clinically acceptable range of actual GFR. In conclusion, the majority of former kidney donors have excellent kidney function and the MDRD formula should be the recommended GFR estimating model in this population.     

Higher Renal Allograft Function in Deceased-Donor Kidney Transplantation Rather Than in Living-Related Kidney Transplantation

Objectives

To compare the clinical outcome of kidney transplantation from living-related and deceased donors.

Change in Renal Function After Laparoscopic Donor Nephrectomy for Kidney Transplantation

Background

Laparoscopic donor nephrectomy (LDN) has become the method of choice for living-donor kidney transplantation. However, LDN may result in decreased renal function in the donor, and risk of end-stage renal failure has been reported.

Objective

To evaluate changes in renal function after LDN.

Patients and Methods

The study included 51 living donors of renal transplants between March 2002 and December 2008. Before kidney donation, we computed the initial function of the kidney preserved in the donor using 24-hour creatinine clearance (Ccr) and functional ratio as revealed at technetium 99m dimercaptosuccinic acid renal scanning. After kidney donation, serum creatinine concentration (sCr) and Ccr were calculated on postoperative day 2 and every 3 months thereafter.

Results

After LDN, mean sCr increased immediately, from 0.90 to 1.31, as did Ccr of the kidney preserved in the donor, from 58.2 to 79.6, a 36.9% increase. A greater percent increase in function was observed in younger donors and those with lower initial Ccr of the preserved kidney. Although 9.8% of donors demonstrated slightly decreased renal function of the preserved kidney at last follow-up, renal function was adequately preserved in most donors.

Conclusion

Younger donors and those with lower initial function of the preserved kidney before nephrectomy demonstrate a greater increase in function after nephrectomy. Age might be a risk factor for decreased renal function after LDN. Older potential living donors may need more careful evaluation before kidney donation.     

Long-Term Deterioration of Kidney Allograft Function

Although long-term survival after kidney transplantation is critically dependent on maintaining stable allograft function, few studies have examined renal allograft function over time. Using pooled data from 10 278 consecutive transplants at five centers, we calculated slopes of estimated glomerular filtration rates (eGFR) measured after 1, 6 and 12 months in 9515, 8861 and 7359 patients surviving > or =1, > or =6 and > or =12 months, respectively. Slopes of eGFR progressively diminished for patients transplanted during 1984-1989, 1990-1993, 1994-1998 and 1999-2002 (analysis of variance p < 0.0001 and p = 0.1245 for slopes measured after 1 and 6 months, respectively). Slopes measured after 12 months were less in the most recent era: -2.2 +/- 7.2 mL/min/1.73 m(2)/year, -2.3 +/- 6.6 mL/min/1.73 m(2)/year, -2.4 +/- 7.4 mL/min/1.73 m(2)/year and -1.4 +/- 10.9 mL/min/1.73 m(2)/year, respectively, p = 0.0058. Slopes measured after 1, 6 and 12 months each were less for transplantations during 1999-2002, after adjusting for multiple transplantation characteristics (p < 0.0001). Similarly, in Cox proportional hazards analysis, the risk (95% CI) for a 25% reduction in eGFR was 0.92 (0.85-1.01), p = 0.0736 during 1990-1994; 0.94 (0.82-1.08), p = 0.4111 during 1995-1998 and 0.78 (0.64-0.95), p = 0.0110 during 1999-2002 (compared to 1984-1989). We conclude that the rate of decline in allograft function after kidney transplantation has improved, suggesting that stable, long-term function may be achievable.     

肾移植患者血清胱抑素C与肌酐清除率相关性的研究

目的探讨肾移植患者血清胱抑素C（SCysC）浓度作为移植肾功能测定指标的可行性和临床应用价值。方法采用颗粒增强透射免疫比浊法（PETIA）分别检测39例初次肾移植患者在术前、术后1周和4周的SCysC水平,并与血清肌酐（Scr）、内生肌酐清除率（Ccr）进行比较分析。结果肾移植术前与术后,患者的SCysC与Scr、Ccr都具有很好的相关性。SCysC与Scr呈正相关（术前r=0.849;术后r=0.940）;与Ccr呈负相关（术前r=-0.857;术后r=-0.876）;按Ccr分组的统计分析结果显示：不同肾功能水平的SCysC与Ccr的相关性均较Scr与Ccr的相关性相似或更佳。当50≤Ccr〈80mL/（min.1.73m^2）时,SCysC与Ccr的相关性要明显优于Scr与Ccr的相关性（P〈0.05）。结论在肾移植患者中,SCysC浓度与Scr浓度和Ccr有较好的相关性,可成为评估移植肾功能的较理想指标。