Urea reduction ratio

The urea reduction ratio (URR), is a dimensionless numberused to quantify hemodialysistreatment adequacy.

It is defined as:

<math>URR = \frac{U_{pre}-U_{post}}{U_{pre}} \times 100% </math>

Where:

• U_pre is the pre-dialysis urealevel
• U_post is the post-dialysis urea level

In the standard thrice hemodialysis schedule a URR of 65% is considered the minimum acceptable. URR has been correlated with survival for thrice weekly dialysis.

The URR decreases if dialysis is done more frequently, as the mass removed is spread over more dialysis sessions. A lower URR under these conditions does not necessarily mean that the dialysis is inadequate.

The numeratorof the URR definition is the removal of urea in the dialysis session, if the urea produced during the dialysis is ignored. In steady state, if the generation of urea is a constant, the URR is proportional to 1/U_pre.

See also

• Clearance
• Hemodialysis
• Hemodialysis product
• Kt/V
• Standardized Kt/V
• Time-averaged concentration(TAC)

External links

• Hemodialysis Dose and Adequacy- a description of URR and Kt/V from the Kidney and Urologic Diseases Clearinghouse.

Calculators

• Kt/V calculator- medindia.com
• TAC calculator- medindia.com
• Nephrology Calculator- does various renal calculations.

This article is licensed under the GNU Free Documentation License.
It uses material from the http://en.wikipedia.org/wiki/Urea+reduction+ratio Wikipedia article Urea reduction ratio.