Urea Reduction Ratio, URR
As discussed in a previous post “Clearance, Kt/V, and Concentration…”, we will use the Kt/V metric to measure the effectiveness of dialysis. There are other methods that are used: one of these is the Urea Reduction Ratio, URR. URR is a fractional decrease in Blood Urea Nitrogen, BUN, in a single dialysis session. It is related to Kt/V.
Blood Urea Nitrogen, BUN, is the standard test, along with creatinine, for evaluating kidney function. For our evaluation of the dialyser we will measure the initial concentration, C0, and concentration at the end of a set time or set number of passes through the dialyser, C(t) or CN.
Clinicians look for Kt/V >1.2 at a minimum (goal of 1.4).
This translates to URR > 0.7 (0.75 goal)