Sieving coefficient inaccuracies during hemodiafiltration in patients withhyperbilirubinemia

Hemodiafiltration has assumed an important role in the supportive therapy o f critically ill patients. The viability of the filter used for hemodiafilt ration can be monitored by estimating the sieving coefficient of small mole cules such as creatinine and/or urea. We report on three patients with seve re hyperbilirubinemia whose creatinine sieving coefficient was spuriously e levated as a result of discordance in the accuracy of creatinine measuremen t in plasma and ultrafiltrate respectively. This discordance was a conseque nce of lack of bilirubin clearance during hemodiafiltration. As a result, w hile the plasma creatinine determination by the kinetic Jaffe method was ne gatively influenced by the hyperbilirubinemia, the ultrafiltrate creatinine was not. This report is the first to document the lack of bilirubin cleara nce during hemodiafiltration and its impact on the calculation of sieving c oefficient based on creatinine. The use of urea as the solute for determini ng the sieving coefficient allows for an accurate estimate and provides a v alid means of monitoring this parameter in the setting of hyperbilirubinemi a.