Sign in →

Test ID RCTUR Creatinine, Random, Urine


Specimen Required


Supplies: Urine Tubes, 10 mL (T068)

Container/Tube: Plastic, 10-mL urine tube

Specimen Volume: 6 mL

Collection Instructions:

1. Collect a random urine specimen.

2. No preservative.


Forms

If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.

Secondary ID

610603

Useful For

Calculation of creatinine clearance, a measure of renal function, when used in conjunction with serum creatinine

 

Normalization of urinary analytes by creatinine concentration to account for the variation in urinary concentrations between subjects

Method Name

Enzymatic Colorimetric Assay

Reporting Name

Creatinine, Random, U

Specimen Type

Urine

Specimen Minimum Volume

1 mL

Specimen Stability Information

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

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 of the filtered creatinine is excreted in the urine. Renal tubular secretion of creatinine also contributes to a small proportion of excreted creatinine. Although most excreted creatinine is derived from an individual's muscle, 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, for the most part, in the urine only comes 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

≥18 years old: 16-326 mg/dL

 

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

Cautions

Twenty-four-hour specimens are preferred for determining creatinine clearance.

 

Intra-individual variability in creatinine excretion may be due to differences in muscle mass or amount of ingested meat.

 

Acute changes in glomerular filtration rate, before a steady state has developed, will alter the amount of urinary creatinine excreted.

Day(s) Performed

Monday through Sunday

Report Available

1 to 3 days

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

NY State Approved

Yes