Application of Cystatin C Reduction Ratio to High-Flux Hemodialysis as an Alternative Indicator of the Clearance of Middle Molecules

Background/Aims: Although high-flux (HF) dialyzers with enhanced membrane permeability are widely used in current hemodialysis (HD) practice, urea kinetic modeling is still being applied to indicate the adequacy of both low-flux (LF) and HF HD. In comparison with urea (molecular weight, 60 Da) and ??2-microglobulin (??2MG, 12 kDa), cystatin C (CyC, 13 kDa) is a larger molecule that has attractive features as a marker for assessing solute clearance. We postulated that CyC might be an alternative for indicating the clearance of middle molecules (MMs), especially with HF HD. Methods: Eighty-nine patients were divided into LF and HF groups. Using single pool urea kinetic modeling, the urea reduction ratio (URR) and equilibrated Kt/Vurea (eKt /Vurea) were calculated. The serum CyC concentrations were measured using particle-enhanced immunonephelometry. As indices of the middle molecular clearance, the reduction ratios of ??2MG and CyC were calculated. Results: The ??2MG reduction ratio (??2MGRR) and CyC reduction ratio (CyCRR) were higher in the HF group compared to the LF group. However, the URR and eKt/Vurea did not differ between the two groups. The CyCRR was significantly correlated with the eKt/Vurea and ??2MGRR (r = 0.47 and 0.69, respectively, both p < 0.0001). Conclusions: Compared to the LF dialyzer, the HF dialyzer removed CyC and ??2MG more efficiently. Unlike the ??2MGRR, the CyCRR was correlated with the eKt/Vurea and ??2MGRR. This study suggests a role for the CyCRR as an alternative indicator of the removal of MMs

Measuring Residual Renal Function in Hemodialysis Patients without Urine Collection

This is the peer reviewed version of the following article: Wong, J., Kaja Kamal, R. M., Vilar, E. and Farrington, K. (2017), 'Measuring Residual Renal Function in Hemodialysis Patients without Urine Collection', Seminars in Dialysis, Vol. 30 (1): 39–49, which has been published in final form at doi: 10.1111/sdi.12557. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. © 2016 Wiley Periodicals, Inc.Many patients on hemodialysis retain significant residual renal function (RRF) but currently measurement of RRF in routine clinical practice can only be achieved using inter-dialytic urine collections to measure urea and creatinine clearances. Urine collections are difficult and inconvenient for patients and staff, and therefore RRF is not universally measured. Methods to assess RRF without reliance on urine collections are needed since RRF provides useful clinical and prognostic information and also permits the application of incremental hemodialysis techniques. Significant efforts have been made to explore the use of serum based biomarkers such as cystatin C, β-trace protein and β2 -microglobulin to estimate RRF. This article reviews blood-based biomarkers and novel methods using exogenous filtration markers which show potential in estimating RRF in hemodialysis patients without the need for urine collection.Peer reviewedFinal Accepted Versio