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22855 Renal Failure Indices

Renal Failure Indices
Test Code: RI
Synonyms/Keywords
Fractional Excretion of Sodium, Renal Failure Index, RFI​
Test Components
Urine Creatinine and Sodium
Blood Creatinine and Sodium​
Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)		 Pediatric Minimum Volume
(no repeat)
​No
Urine​
Urine Container
10 mL​
0.5 mL ​
 ​
                               ​​​Submit either serum OR plasma, not both
​No ​Serum ​Serum Separator Tube (SST) ​Red Top Tube (RTT) ​2 mL ​0.3 mL ​
No​ ​Plasma ​Lithium-heparin Plasma Separator Tube (PST) ​Lithium or Sodium-heparin Green Top Tube (GTT) ​2 mL ​0.3 mL ​
Collection Processing Instructions
Blood specimen must be obtained within 8 hours of the urine collection. Random urine without preservative is preferred.  Specimens collected with 0.5 g sulfamic acid, 6N HCl, 33% acetic acid, or boric acid are also acceptable.
Specimen Stability Information
Specimen Type Temperature Time
Urine - No Preservative​ ​Ambient ​2 hours
Refrigerate​ 4 days​
Urine - With Preservative​ ​Refrigerate ​7 days
Serum/Plasma ​ ​ Ambient​ 5 days
Refrigerate​ 1 week
Frozen​ 2 months
Rejection Criteria
​​If either the blood or urine specimen is not available, the test cannot be performed
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
Marshfield​ Monday through Sunday​ 2-4 hours​ Modified Jaffe Kinetic Fixed Assay & ISE/Beckman AU
Test Information
When urine specimen arrives in the laboratory, check the computer for a serum sodium and creatinine order for collection within 8 hours of urine collection time. If serum tests not previously ordered, request RI-BLD and notify Hospital Phlebotomy that the blood specimen needs to collected on their next round. Results for both the Fractional Excretion of Sodium and the Renal Failure Index are reported under this test code.​
Reference Range Information
Performing Location Reference Range
Marshfield​ <1 implies pre-renal azotemia
Values >1 may indicate acute renal failure​
Outreach CPTs
CPT Modifier
(if needed)		 Quantity Description Comments
84300   ​ ​ ​  Sodium, urine  ​ ​
82570  ​ ​ ​ Creatinine, other source​ ​
84295 ​ ​ ​ Sodium, serum ​ ​
82565​ ​ ​  Creatinine, blood ​ ​
Synonyms/Keywords
Fractional Excretion of Sodium, Renal Failure Index, RFI​
Test Components
Urine Creatinine and Sodium
Blood Creatinine and Sodium​
Ordering Applications
Ordering Application Description
​Centricity ​Renal Indices/Na Exc
​Cerner ​Renal Indices/Incl Frac. Na Excre.
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)		 Pediatric Minimum Volume
(no repeat)
​No
Urine​
Urine Container
10 mL​
0.5 mL ​
 ​
                               ​​​Submit either serum OR plasma, not both
​No ​Serum ​Serum Separator Tube (SST) ​Red Top Tube (RTT) ​2 mL ​0.3 mL ​
No​ ​Plasma ​Lithium-heparin Plasma Separator Tube (PST) ​Lithium or Sodium-heparin Green Top Tube (GTT) ​2 mL ​0.3 mL ​
Collection Processing
Blood specimen must be obtained within 8 hours of the urine collection. Random urine without preservative is preferred.  Specimens collected with 0.5 g sulfamic acid, 6N HCl, 33% acetic acid, or boric acid are also acceptable.
Specimen Stability Information
Specimen Type Temperature Time
Urine - No Preservative​ ​Ambient ​2 hours
Refrigerate​ 4 days​
Urine - With Preservative​ ​Refrigerate ​7 days
Serum/Plasma ​ ​ Ambient​ 5 days
Refrigerate​ 1 week
Frozen​ 2 months
Rejection Criteria
​​If either the blood or urine specimen is not available, the test cannot be performed
Test Components
Urine Creatinine and Sodium
Blood Creatinine and Sodium​
Reference Range Information
Performing Location Reference Range
Marshfield​ <1 implies pre-renal azotemia
Values >1 may indicate acute renal failure​
For more information visit:
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
Marshfield​ Monday through Sunday​ 2-4 hours​ Modified Jaffe Kinetic Fixed Assay & ISE/Beckman AU
For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)		 Quantity Description Comments
84300   ​ ​ ​  Sodium, urine  ​ ​
82570  ​ ​ ​ Creatinine, other source​ ​
84295 ​ ​ ​ Sodium, serum ​ ​
82565​ ​ ​  Creatinine, blood ​ ​
For most current information refer to the Marshfield Laboratory online reference manual.