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HelpTest Code CRE2 Creatinine, Urine
Specimen Required
Only orderable as part of a profile. For more information see:
-ALBR / Albumin, Random, Urine
-RALB / Albumin, Random, Urine.
Supplies: Sarstedt 5 mL Aliquot Tube (T914)
Container/Tube: Plastic tube
Specimen Volume: 5 mL
Collection Instructions:
1. Collect a random urine specimen.
2. No preservative.
Useful For
Normalization of 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:
ALBR / Albumin, Random, Urine
RALB / Albumin, Random, Urine.
Enzymatic Colorimetric Assay
Reporting Name
CreatinineSpecimen Type
UrineSpecimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Refrigerated (preferred) | 30 days | |
| Ambient | 30 days | ||
| Frozen | 30 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 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 (GFR). 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
Only orderable as part of a profile. For more information see:
ALBR / Albumin, Random, Urine
RALB / Albumin, Random, Urine.
Not applicable
Interpretation
Decreased creatinine clearance indicates decreased glomerular filtration rate. This can be due to conditions such as progressive renal 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 commonly seen during pregnancy or in patients with diabetes mellitus, before diabetic nephropathy has occurred. It also may occur with large dietary protein intake.
Cautions
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.
Method Description
The 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)
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
82570
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| CRE2 | Creatinine | 2161-8 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| CRE2 | Creatinine | 2161-8 |
Day(s) Performed
Monday through Sunday