Estimation of renal function in adult kidney transplant recipients by equations

Clinical Accuracy of Average Creatinine and Cystatin-C-Based Estimated GFR in Japanese Living Renal Transplantation Donors

OBJECTIVE

To evaluate the clinical accuracy of several estimated glomerular filtration rates (eGFR) using cystatin-C to measure renal function in Japanese renal donors.

METHODS

In total, 61 healthy, potential renal donors were assessed. The average age was 42.7 years (range: 27-67). We evaluated the GFR based on the 24-hour creatinine clearance (Ccr) using 24-hour urine collection, eGFR based on serum creatinine (eGFRcr), and cystatin-C (eGFRcys) levels using an equation developed by the Japanese Society of Nephrology, the average of the eGFRcr and eGFRcys (eGFRave) rates, and an eGFR based on a combination of serum creatinine and cystatin-C values using an equation developed by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI). The association between Ccr and each eGFR was evaluated using Pearson's r and the Bland-Altman plot.

RESULTS

Pearson's correlation coefficient analysis revealed a significant correlation between the Ccr and the eGFRcr (r = 0.62, P < .0001), eGFRave (r = 45, P = .0003), and eGFRcr-cys (r = 0.451, P = .0014). The Bland-Altman study suggested that each eGFR had a low level of agreement with the Ccr because the latter was higher than each eGFR. On the other hand, the eGFRave had the highest level of agreement with CCr × 0.715.

CONCLUSIONS

The eGFRave may provide a simple and useful method of evaluating renal function in living renal transplant donors.

Evaluation of renal function by cystatin C in renal transplant recipients

OBJECTIVES

We evaluated cystatin C concentration as a marker of glomerular filtration rate in renal transplant recipients, and its correlation with creatinine-based glomerular filtration rate by urinary creatinine clearance, and the Cockroft-Gault and Modification of Diet in Renal Disease formulas.

MATERIALS AND METHODS

In this cross-sectional study, we measured serum cystatin C levels and its correlation with serum creatinine, creatinine clearance, and glomerular filtration rate using the Cockroft-Gault formula and Modification of Diet in Renal Disease formulas.

RESULTS

One hundred two recipients between June and December 2012, were examined. The mean subject age was 31.87 ± 8.37 years; the male:female ratio was 4.3:1. Mean serum creatinine concentration was 141.44 ± 43.31 mol/L (1.60 ± 0.49 mg/dL) and serum cystatin C 122.09 ± 38.95 nmol/L (1.63 ± 0.52 mg/L). Serum cystatin C was significantly correlated with serum creatinine (r=0.90; P<.001), creatinine clearance (r=0.77; P<.001), and the Cockroft-Gault (r=0.73; P<.001) and the Modification of Diet in Renal Disease formulas (r=0.82; P<.001). We assessed the correlation among serum cystatin C with serum creatinine, creatinine clearance, the Cockroft-Gault and Modification of Diet in Renal Disease at 1, 2-3, 4-5, and more than 5 years after transplant. The correlation between serum cystatin C and serum creatinine ranged from 0.8 to 1.0; cystatin C and creatinine clearance ranged from 0.8 to 0.85; serum cystatin C and the Cockroft-Gault Formula ranged from 0.7 to 0.8; and serum cystatin C and the Modification of Diet in Renal Disease formulas ranged from 0.8 to 0.84.

CONCLUSIONS

Our results show that serum cystatin C is a reliable marker for estimating glomerular filtration rate among renal transplant recipients. This test can determine the glomerular filtration rate of renal transplant recipients on follow-up. Further studies are required to establish serum cystatin C as a standard test for monitoring glomerular filtration rate in transplanted patients.

Serum Cystatin C in Estimating Glomerular Filtration Rate

Using serum cystatin C in estimating glomerular filtration rate (GFR) has in recent times been recommended. A number of simple formulas for calculating GFR have been derived specifically from serum cystatin C concentrations. The purpose of this study was to assess the significance of cystatin C and of the two most frequently applied of these formulas in estimating glomerular filtration rate compared to serum creatinine and its derived formulas for estimating glomerular filtration rate from creatinine concentrations. The study included 74 patients: 59 were in various stages of chronic renal insufficiency (divided into two subgroups: I with GFR ≥ 60 mL/min/1.73m2and II with GFR<60 mL/min/1.73m2) and 15 on hemodialysis. A control group of 30 healthy participants was also included in the study. Serum values of cystatin C ranged from: 0.86 ± 0.16 mg/L in subgroup I, and 1.77 ± 0.79 mg/L in subgroup II, to 6.9 ± 1.83 mg/L in patients on hemodialysis. The correlation between the two formulas derived from cystatin C and the clearance of creatinine, as well as the Cockcroft and Gault's formula, was significant, while one of the formulas derived from cystatin C did not show a significant correlation with MDRD. It was concluded that serum cystatin C is a significant marker in estimating glomerular filtration rate, especially in the advanced stages of chronic renal insufficiency.