Accessible online at: www.karger.com/journals/nef Dear Sir, Our efforts to increase the efficiency of the dialysis process have, so far, focussed on what happens within the dialyser. Augmenting such parameters as blood and dialysis fluid flowrates and dialyser surface area enhances small solute clearance. [1, 2] The hitherto neglected aspect is that the real membrane exchange area is not within...