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Calculator: Residual renal function in hemodialysis patients (Kru)

Calculator: Residual renal function in hemodialysis patients (Kru)

ID urine volume  
Urine urea concentration  
ID period  

Important: Inputs must be complete to perform calculation.

Mean BUN  
Decimal precision  


  • U1 is the BUN just after the first dialysis of the week.
  • U2 is the BUN just prior to the second dialysis of the week.
  • ID: interdialytic; BUN: blood urea nitrogen; RRF: residual renal function.

Equations used
Mean_BUN = (U1 + U2) / 2
RRF = ID_urine_volume * Urine_urea_concentration / ID_period / Mean_BUN


  1. Daugirdas JT, Ing TS. Handbook of Dialysis, 2nd ed, Little, Brown 1994.
Only digits 0 to 9 and a single decimal point (".") are acceptable as numeric inputs. Attempted input of other characters into a numeric field may lead to an incorrect result.

Information on this page may not appear correctly if printed.

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All information contained in and produced by the EBMcalc system is provided for educational purposes only. This information should not be used for the diagnosis or treatment of any health problem or disease. THIS INFORMATION IS NOT INTENDED TO REPLACE CLINICAL JUDGMENT OR GUIDE INDIVIDUAL PATIENT CARE IN ANY MANNER. Click here for full notice and disclaimer.

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