A growing number of publications supports a biologic effect of the protein-bound uremic
retention solutes indoxyl sulfate and p-cresyl sulfate. However, the use of unrealistically high
free concentrations of these compounds and/or inappropriately low albumin concentrations
may blur the interpretation of these results. Here, we performed a systematic review,
selecting only studies in which, depending on the albumin concentration, real or
extrapolated free concentrations of indoxyl sulfate and p-cresyl sulfate remained in the …