Urea Reduction Ratio [URR]

URR is used to measure how effective a haemodialysis treatment is. It is based on tests of blood urea, by measuring the levels before and after treatment, to show how much has been removed. Kt/V is another test of haemodialysis effectiveness: some units use URR, some use Kt/V, some use both.

In the UK the agreed target URR is a minimum of 65%. This applies to someone receiving dialysis three times each week. If your own kidneys are still working a bit, a slightly lower URR may be acceptable.

Lower values are associated with shorter survival on dialysis. Of course other things affect how long you will live too - another important one is not gaining too much fluid between treatments. A single low value is nothing to get too worried about if all other values are over 65%.

Causes of low URR include

How to improve URR and/or dialysis dose - possibilities include


More information about URR and Kt/V from the NIDDK (USA) - detailed and thorough


This page created 20th July 2005, last modified July 9, 2015, on the PatientView website