Which statement about URR is correct in dialysis adequacy assessment?

• A. It is often used alongside Kt/V to gauge removal of urea
• B. It measures phosphate clearance
• C. It is identical to Kt/V
• D. It has no role in contemporary dialysis adequacy assessment

Answer: (A)

Urea Reduction Ratio (URR) is a simple measure of how much urea is removed during a dialysis session. It’s calculated by comparing the urea level before the session to the level after the session and expressing the drop as a percentage of the starting value. This provides a quick sense of how effectively small-solute urea is being cleared.

In practice, URR is often used alongside Kt/V to gauge dialysis adequacy. URR gives a straightforward read on urea removal, while Kt/V adds a dose perspective by accounting for how long the session lasts, the clearance rate, and the patient’s urea distribution volume. Using both together gives a fuller picture of dialysis adequacy than either measure alone.

URR does not measure phosphate clearance; that’s a different solute with distinct kinetics. It is not identical to Kt/V, since Kt/V incorporates time and volume factors to reflect overall clearance relative to the patient’s urea distribution. And URR still has a role in contemporary assessment, though it’s interpreted alongside other metrics like Kt/V rather than used in isolation.