Time-averaged concentration estimation of uremic toxins with different removal kinetics: a novel approach based on intradialytic spent dialysate measurements


 
 
 Kt/Vurea is the most used marker to estimate dialysis adequacy; however, it does not reflect the removal of many other uremic toxins, and a new approach is needed. We have assessed the feasibility of estimating intradialytic serum time-averaged concentration (TAC) of various uremic toxins from their spent dialysate concentrations that can be estimated non-invasively online with optical methods.
 
 
 
 Serum and spent dialysate levels and total removed solute (TRS) of urea, uric acid (UA), indoxyl sulfate (IS) and β2-microglobulin (β2M) were evaluated with laboratory methods during 312 hemodialysis sessions in 78 patients with 4 different dialysis treatment settings. TAC was calculated from serum concentrations and evaluated from TRS and logarithmic mean concentrations of spent dialysate (Mln D).
 
 
 
 Mean intradialytic serum TAC values of urea, UA, β2M and IS were 10.4±3.8 mmol/L, 191.6±48.1 µmol/L, 13.3±4.3 mg/L and 82.9±43.3 µmol/L, respectively. These serum TAC values were similar and highly correlated to those estimated from TRS: 10.5±3.6 mmol/L (R2 = 0.92), 191.5±42.8 µmol/L (R2 = 0.79), 13.0±3.2 mg/L (R2 = 0.59), and 82.7±40.0 µmol/L (R2 = 0.85) and from Mln D 10.7±3.7 mmol/L (R2 = 0.92), 191.6±43.8 µmol/L (R2 = 0.80), 12.9±3.2 mg/L (R2 = 0.63), and 82.2±38.6 µmol/L (R2 = 0.84), respectively.
 
 
 
 Intradialytic serum TAC of different uremic toxins can be estimated non-invasively from their concentration in spent dialysate. This sets the stage for TAC estimation from online optical monitoring of spent dialysate concentrations of diverse solutes and for further optimization of estimation models for each uremic toxin.
