Is My Blood Getting Cleaned During Dialysis?

Provided by DaVita® Dietitians

Healthy kidneys work 24 hours a day, seven days a week. When kidneys stop working, dialysis does this job, but it only does some of the work. It is possible to live a long and healthy life receiving dialysis three times a week by ensuring that your blood is optimally cleaned during each treatment.

The dialysis center uses a test called urea reduction ratio, or URR, to show how well your blood is cleaned during your treatments. Every month you will see your results on your nutrition report. The goal is a score of 65 percent or better on the URR test.

How can I reach a URR of 65 percent?

Getting the right amount of dialysis can help you live a longer and healthier life. Here are some things that you can do to reach a URR of 65 percent:

  • Don’t leave your treatment early or arrive late to your appointment.
  • Try to use the restroom before treatment so you don’t have to stop in the middle of your session.
  • A catheter access may cause your results to be low, because blood flow rate is usually slower with a catheter. If possible, get a fistula or graft instead of a catheter to receive hemodialysis.
  • If your access is not working well, make an appointment to have your access checked.

There are exceptions, of course, and some causes of a low URR reading can be out of your hands. For instance, if you experience cramping or low blood pressure, your blood flow rate may decrease. This will result in less cleaning of your blood.

What happens if my blood isn’t cleaned well enough?

If you do not get enough dialysis, you may experience one or more of the following symptoms:

  • Your skin turns yellow or itches.
  • You have swelling in your feet or legs.
  • It is difficult to sleep.
  • You lose your appetite.
  • You feel short of breath.
  • You feel tired or depressed.
  • Your life can be shortened.


When you stay on your dialysis treatment for the entire time prescribed, you’re more likely to reach the URR goal of 65 percent. The URR test indicates how well your blood is being cleaned during your treatment. Arrive at your treatments on time, get a fistula or graft and be mindful of your fluid intake. Also, work with your kidney healthcare team so they can help you live a longer and healthier life on dialysis.