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Test Code CRTFR Creatinine, Random, Urine


Specimen Required


Only orderable as part of a profile. For more information see:

-RLTE4 / Leukotriene E4, Random, Urine.

-TIUCR / Titanium/Creatinine Ratio, Random, Urine

 

Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Container/Tube: Plastic, 5-mL tube

Specimen Volume: 5 mL

Collection Instructions:

1. Collect a random urine specimen.

2. No preservative.


Secondary ID

618560

Useful For

Normalizing urinary analytes to account for the variation in urinary concentrations between individuals when using random urine collections

Method Name

Only orderable as part of a profile. For more information see:

-RLTE4 / Leukotriene E4, Random, Urine.

-TIUCR / Titanium/Creatinine Ratio, Random, Urine

 

Enzymatic Colorimetric Assay

Reporting Name

Creatinine, Random, U

Specimen Type

Urine

Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Urine Frozen (preferred) 30 days
  Refrigerated  30 days
  Ambient  14 days

Reject Due To

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Clinical Information

Creatinine is formed from the metabolism of creatine and phosphocreatine, both of which are principally found in muscle. Thus, the amount of creatinine produced is, in large part, dependent upon the individual's muscle mass and tends not to fluctuate much from day-to-day.

 

Creatinine is not protein bound and is freely filtered by glomeruli. All filtered creatinine is excreted in the urine. Renal tubular secretion of creatinine contributes a small proportion of excreted creatinine. Although most excreted creatinine is derived from an individual's muscle mass, dietary protein intake, particularly of cooked meat, can contribute to urinary creatinine levels.

 

The renal clearance of creatinine provides an estimate of glomerular filtration rate. Since creatinine in the urine only comes mainly from filtration, the concentration of creatinine reflects overall urinary concentration. Therefore, creatinine can be used to normalize other analytes in a random urine specimen.

Reference Values

Only orderable as part of a profile. For more information see:

-RLTE4 / Leukotriene E4, Random, Urine.

-TIUCR / Titanium/Creatinine Ratio, Random, Urine

 

≥18 years old: 16-326 mg/dL

Reference values have not been established for patients who are younger than 18 years of age.

Interpretation

Decreased creatinine clearance indicates decreased glomerular filtration rate. This can be due to conditions, such as progressive kidney disease, or result from adverse effect on renal hemodynamics that are often reversible, including certain drugs or from decreases in effective renal perfusion (eg, volume depletion or heart failure).

 

Increased creatinine clearance is often referred to as "hyperfiltration" and is most frequently seen during pregnancy or in patients with diabetes mellitus before diabetic nephropathy has occurred. It may also occur with large dietary protein intake.

Method Description

This enzymatic method is based on the determination of sarcosine from creatinine with the aid of creatininase, creatinase, and sarcosine oxidase. The liberated hydrogen peroxide is measured via a modified Trinder reaction using a colorimetric indicator. Optimization of the buffer system and the colorimetric indicator enables the creatinine concentration to be quantified both precisely and specifically.(Package insert: Creatinine plus ver 2. Roche Diagnostics; V15.0, 03/2019)

Day(s) Performed

Monday through Sunday

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

82570

LOINC Code Information

Test ID Test Order Name Order LOINC Value
CRTFR Creatinine, Random, U 2161-8

 

Result ID Test Result Name Result LOINC Value
CRTFR Creatinine, Random, U 2161-8