Glomerular filtration rate estimation in renal transplant patients based on serum cystatin-C levels: Comparison with other markers of glomerular filtration rate

Estimating GFR in adult patients with hematopoietic cell transplant: comparison of estimating equations with an iohexol reference standard

BACKGROUND AND OBJECTIVES

Formal evaluation of kidney function before and after hematopoietic cell transplant is important to determine conditioning regimens, type of transplant, and medication dosing. Serum creatinine and estimating equations may not accurately assess kidney function.

DESIGN, STUDY, PARTICIPANTS, & MEASUREMENTS

Existing estimating equations for GFR were compared with an iohexol measure of GFR in a prospective cohort study of 50 patients undergoing hematopoietic cell transplant and subsequent care at the Fred Hutchinson Cancer Research Institute from 2009 to 2013. Patients underwent iohexol GFR, serum creatinine, and cystatin C determination at baseline and day 100 posthematopoietic cell transplant. Iohexol GFR measurements were compared with the CKD Epidemiology Collaboration, Inker CKD Epidemiology Collaboration cystatin C with and without serum creatinine, Modification of Diet in Renal Disease, and Cockcroft-Gault estimating equations using Bland-Altman analysis and McNemar's test. The iohexol measurements were also compared with blood samples collected simultaneously on filter paper.

RESULTS

Mean differences between iohexol GFR and eGFR on the basis of Bland-Altman analyses ranged from -20.6 to +15.4 ml/min per 1.73 m(2) at baseline and -12.7 to +12.9 ml/min per 1.73 m(2) at day 100. The CKD Epidemiology Collaboration and Modification of Diet in Renal Disease estimating equations classified 64% of patients with a GFR<90 at baseline compared with 38% by iohexol GFR (P=0.003 and P<0.01, respectively). No statistically significant differences were seen at day 100. The filter paper GFR had a mean difference of 0 at baseline and 5.9 at day 100. Additionally, 21%-37% and 57%-89% of eGFRs were within 10% and 30%, respectively, of the iohexol GFR at baseline, and 16%-34% and 72%-84% were within 10% and 30%, respectively, of the iohexol GFR at day 100; 98% of the filter paper estimates at baseline were within 30%, and 46% were within 10% of iohexol GFR.

CONCLUSIONS

The estimating equations are neither accurate nor precise in the hematopoietic cell transplant population, and clinical decision may require measurement of GFR.

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.

A meta-analysis on diagnostic value of serum cystatin C and creatinine for the evaluation of glomerular filtration function in renal transplant patients

OBJECTIVES

This meta-analysis aimed to perform a systematic review on comparing the diagnostic value of serum cystatin C and creatinine for glomerular filtration rate in renal transplant patients.

METHODS

The data was extracted into 2×2 table after the articles were assessed by the tool of QUADAS and heterogeneity analysis. The SROC curve and meta-analysis were performed by MetaDisc1.4.

RESULTS

Meta-analysis showed that the serum cystatin C had no heterogeneity (P=0.418, I2=2.2%, DOR=25.03), while creatinine heterogeneity was high (P=0.109, I2=37.5%, DOR=9.11). The values of SEN, SPE and SAUC were calculated as 0.86, 0.70 and 0.9015 for cystatin C, and 0.78, 0.73 and 0.8285 for creatinine individually. This study utilized GFR detection and subgroups analysis by cutoff. The PLR was 6.13 and the NLR was 0.12 for cystatin C, compared to SCr (3.72, 0.32). There was homogeneity among these studies using PENIA testing for cystatin C (χ2=2.61, P=0.4560, I2=0.0%.

CONCLUSIONS

There were significant correlations among cystatin C , creatinine and glomerular filtration rate (GFR). Cystatin C had more sensitivity but less specificity than creatinine for evaluation of GFR. Cystatin C had strong ability in diagnosing renal function after renal transplant and ruling out diagnostic efficacy.

Clinical Use and Pathogenetic Basis of Laboratory Tests for the Evaluation of Primary Arterial Hypertension

This review focuses on the laboratory biochemical tests that are useful in the diagnostic approach to the hypertensive patient. A "minimal" diagnostic laboratory work-up, including a small number of tests that are simple and relatively inexpensive, is first described. Because these tests provide basic information on the presence of major cardiovascular (CV) risk factors and target organ damage, and might give some clues to the presence of a secondary form of hypertension (HT), they should be performed on all patients presenting with HT. Other tests that are aimed at assessing the overall CV risk, a major determinant of prognosis that dictates the therapeutic strategy in the individual HT patient, are then discussed. They allow identification of major CV risk factors and associated clinical conditions which, if present, lead to a substantial change of therapeutic strategy. The role of C-reactive protein as a marker of atherosclerosis and its predictive value for CV events are also discussed. Finally, a section is devoted to tests that are currently confined to research purposes, such as markers of endothelial function including endothelin-1, homocysteine and genetic analysis.

Chronic kidney disease after liver, cardiac, lung, heart-lung, and hematopoietic stem cell transplant

Patient survival after cardiac, liver, and hematopoietic stem cell transplant (HSCT) is improving; however, this survival is limited by substantial pretransplant and treatment-related toxicities. A major cause of morbidity and mortality after transplant is chronic kidney disease (CKD). Although the majority of CKD after transplant is attributed to the use of calcineurin inhibitors, various other conditions such as thrombotic microangiopathy, nephrotic syndrome, and focal segmental glomerulosclerosis have been described. Though the immunosuppression used for each of the transplant types, cardiac, liver and HSCT is similar, the risk factors for developing CKD and the CKD severity described in patients after transplant vary. As the indications for transplant and the long-term survival improves for these children, so will the burden of CKD. Nephrologists should be involved early in the pretransplant workup of these patients. Transplant physicians and nephrologists will need to work together to identify those patients at risk of developing CKD early to prevent its development and progression to end-stage renal disease.

Improved GFR estimation by combined creatinine and cystatin C measurements

Plasma creatinine may not reflect glomerular filtration rate (GFR) especially in the early stages of chronic kidney disease (CKD). Plasma cystatin C (cysC), however, has the potential to more accurately determine early GFR reduction. We sought to improve the creatinine-based GFR estimation by including cysC measurements. We derived a reference GFR from standard dual plasma sampling (99m)Tc-DTPA clearance in a training cohort of 376 randomly selected adult Chinese patients with CKD. We compared reference values to estimated GFR and applied multiple regression models to one equation based solely on cysC, and to another combining plasma creatinine (Pcr) and cysC measurements of the training cohort. The results were validated by testing an additional 191 patients. The difference, precision, and accuracy of the two estimates were compared with the modified Modification of Diet in Renal Disease (MDRD) equation for Chinese patients, and another estimate combining cysC and modified MDRD calculations. The estimated GFR combining Pcr and cysC measurements more accurately matched the reference GFR at all stages of CKD than the other equations, particularly in patients with near-normal kidney function.

Cystatin C – A Marker for Assessment of the Glomerular Filtration Rate in Patients with Cisplatin Chemotherapy

BACKGROUND

Cystatin C has recently been proposed as an ideal marker for glomerular filtration rate (GFR). In this study, cystatin C serum levels were evaluated in comparison to serum creatinine concentrations and inulin clearances in patients with normal kidney function receiving cisplatin-based chemotherapy to assess the validity of cystatin C as an alternative endogenous marker of GFR.

METHODS

Blood samples for the assessment of cystatin C, creatinine and inulin clearances were collected in patients before and after application of cisplatin in a clinical trial. Overall, 41 patients were included in the study, 35 of them were eligible receiving cisplatin in two different cisplatin-based chemotherapy schedules.

RESULTS

A 21% increase of cystatin C serum levels was demonstrated in the placebo group after application of cisplatin. Analysis of inulin clearances revealed a 23% loss of inulin clearance in patients of the placebo arm. In contrast, significant changes could not be detected by analysis of serum creatinine levels.

CONCLUSIONS

Cystatin C represents a more sensitive clinical marker than serum creatinine for the early assessment of GFR damage caused by cisplatin. Changes in cystatin C serum concentrations correlate well to GFR decrease as measured by inulin clearance.

Assessing glomerular filtration rate in renal transplant recipients by estimates derived from serum measurements of creatinine and cystatin C

BACKGROUND

Assessing glomerular filtration rate (GFR) is of importance in the surveillance of renal transplant recipients. As serum markers alone are inaccurate for estimating GFR, several equations have been developed with the aim of translating a serum value into a corresponding and more accurate GFR. The present study investigated the diagnostic characteristics of GFR estimates obtained by the simplified MDRD formula and the cystatin C based estimate described by Larsson et al.

METHODS

Prospective study in 29 stable renal transplant recipients. GFR was assessed with (125)I-Iothalamate clearance, creatinine was measured with a modified Jaffe method on Dimension RxL (Dade-Behring, Dudingen, Switzerland), cystatin C was determined by particle enhanced turbidimetric immunassay (PETIA; Dako, Glostrup, Denmark). Bias, precision and diagnostic accuracy of the two GFR estimates were assessed with Bland-Altman method and receiver-operating characteristics (ROC) analysis. The latter was performed at a GFR cut-off of 60 ml/min/1.73 m2.

RESULTS

The cystatin C based GFR estimate normalized to a body surface area of 1.73 m2 exhibited a bias of -4.7 ml/min/1.73 m2, the 95% limits of agreement were -25.5-16 ml/min/1.73 m2 with an AUC of 0.87. The MDRD estimates obtained from the original creatinine revealed biased results. Thus, non-constant recalibration of creatinine was done. Recalibrated creatinine gave an MDRD GFR estimate with a bias of 1.7 ml/min/1.73 m2. The limits of agreement were -23.1-26.4 ml/min/1.73 m2. ROC analysis revealed an AUC 0.8 and was not significantly different from the cystatin C based GFR estimate.

CONCLUSIONS

In renal transplant recipients, the cystatin C based GFR estimate exhibits similar diagnostic characteristics like the simplified MDRD formula. In contrast to cystatin C measurement, recalibration of creatinine might be necessary before implementing the simplified MDRD formula into clinical routine.