Dialysis with high-flux membranes significantly affects plasma levels of neutrophil gelatinase-associated lipocalin

I read with interest the recent article by Schilder et al. reporting that plasma levels and the biomarker value of neutrophil gelatinase-associated lipocalin (NGAL) in critically ill patients with acute kidney injury (AKI) are not affected by continuous venovenous hemofiltration (CVVH) [1]. Recently, Honore et al. [2] commented on the data by Schilder et al., suggesting that further studies are warranted to definitely assess the membranes and the dialytic techniques that can remove NGAL from plasma and thus affect its accuracy as a marker of AKI. Our results in 31 patients on maintenance hemodialysis (MHD), published in Critical Care as part of a study that evaluated the effect of glomerular filtration rate impairment on diagnostic performance of NGAL [3], appear quite different from those found by Schilder et al. in critically ill patients who received CVVH. Patients on MHD received low-flux dialysis (23 treatments) with a polysulfone membrane (F8; Fresenius, Bad Homburg, Germany), or different high-flux membranes. High-flux dialysis treatments were performed in 13 patients by using a triacetate cellulose membrane with a surface of 1.9 m and an ultrafiltration rate (UFR) of 8474 mL/h per 100 mm Hg (N190 FH; Nipro, Osaka, Japan). The remaining eight treatments were performed as hemodiafiltration with a polyphenylene membrane with a surface of 2.0 m and a UFR of 6800 mL/h per 100 mm Hg (Phylther; Bellco, Mirandola, Italy) or as an acrylonitril