URR Rates

Have any of you been told that URR’s are different for daily dialysis patients and if so why? I was told that lower URRs are fine for daily dialysis while I would assume that they would be better.


home hemo 9/04
URRs of 64-64%

URR stands for Urea Reduction Ratio. The formula is simple:
(Pre BUN - Post BUN) ÷ Pre Bun) X 100 = URR%
Now consider if you dialyze daily your pre BUN number should be smaller than your pre BUN number when dialyzing three times a week because there was less time for toxins to build up between treatments.

So lets look at some numbers (can you tell I like math?)

Senario 1: Pre BUN = 80; post BUN = 20
Senario 2: Pre BUN = 50; post BUN = 20

Senario 1: (80-20)/80 x 100 = 75%
Senario 2: (50-20)/50 x 100 = 60%

If senario 1 was when an individual dialyzed 3x/week and senario 2 was after switching to 6x/week I’d say senario 2 has better numbers even though the URR is worse. I think the average weekly BUN would be a better measure of dialysis adequacy. I think the lower your average BUN the better. The ratio - URR - is a very rough measure.

I guess since I’ve never done 3x a week dialysis I expected my BUN and creatinine to be much lower than pre dialysis, and finding that they aren’t is what surprises me. Pre dialysis I had a 50’s BUN and Creatinine in the 7s, now with one day off I have BUN of 40’s and Creatinine in the 8’s and then they tell me a 60’s URR is “good”.

Anyone know why the only thing they really consider is BUN? The creatinine never seems to get in a normal range and is continually going higher yet no measurement seems to take that into account. Is creatinine less “dangerous” to you than urea nitrogen??