BACKGROUND AND OBJECTIVES: Cystatin C is a 13.3 kD middle molecule of similar size to β2-microglobulin and a marker of GFR in CKD. This study aimed to determine cystatin C kinetics in hemodialysis to understand whether blood concentrations may predict residual renal function and middle-molecule clearance.
DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Cystatin C removal and rebound kinetics were studied in 24 patients on high-flux hemodialysis or hemodiafiltration. To determine whether cystatin C concentrations are predictable, an iterative two-pool mathematical model was applied.
RESULTS: Cystatin C was cleared effectively, although less than β2-microglobulin (reduction ratios ± SD are 39% ± 11 and 51% ± 11). Cystatin C rebounded to 95% ± 5% of predialysis concentration by 12 hours postdialysis. The two-pool kinetic model showed excellent goodness of fit. Modeled extracellular cystatin C pool volume is smaller than that predicted, comprising 25.5% ± 9.2 of total body water. Iterated parameters, including nonrenal clearance, showed wide interindividual variation. Modeled nonrenal clearance was substantially higher than renal clearance in this population at 25.1 ± 6.6 ml/min per 1.73 m(2) body surface area.
CONCLUSIONS: Plasma cystatin C levels may be used to measure middle-molecule clearance. Levels rebound substantially postdialysis and plateau in the interdialytic period. At low GFR, nonrenal clearance predominates over renal clearance, and its interindividual variation will limit use of cystatin C to predict residual renal function in advanced kidney disease.
|Number of pages||8|
|Journal||Clinical Journal of the American Society of Nephrology (CJASN)|
|Early online date||1 May 2014|
|Publication status||Published - 7 Jul 2014|
- Body Surface Area
- Body Water
- Cystatin C
- Extracellular Fluid
- Glomerular Filtration Rate
- Kidney Diseases
- Middle Aged
- Models, Biological
- Molecular Weight
- Predictive Value of Tests
- Renal Dialysis