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HelpTest ID CRT2F Creatinine, 24 Hour, Urine
Specimen Required
Only orderable as part of a profile. For more information see TLTE4 / Leukotriene E4, 24 Hour, Urine.
Secondary ID
618161Useful For
Normalizing urinary analytes to account for the variation in urinary concentration
Method Name
Only orderable as part of a profile. For more information see TLTE4 / Leukotriene E4, 24 Hour, Urine.
Enzymatic Colorimetric Assay
Reporting Name
Creatinine, 24 HR, USpecimen Type
UrineSpecimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | |
|---|---|---|---|
| Urine | Frozen (preferred) | 30 days | |
| Refrigerated | 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 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.
Reference Values
Only orderable as part of a profile. For more information see TLTE4 / Leukotriene E4, 24 Hour, Urine.
Normal values mg per 24 hours:
Males: 930-2955 mg/24 hours
Females: 603-1783 mg/24 hours
Reference values have not been established for patients who are younger than 18 years of age.
Cautions
The reliability of 24-hour urinary creatinine determinations is, as for all timed urine collections, very dependent on accurately collected 24-hour specimens.
Intraindividual 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.
Rifampicin, levodopa, and calcium dobesilate (eg, Dexium) cause artificially low creatinine results. According to Clinical and Laboratory Standards Institute guidelines, methyldopa, as tested, causes artificially low creatinine results.
Dicynone (etamsylate) at therapeutic concentrations may lead to falsely low results.
N-ethylglycine at therapeutic concentrations and DL-proline at concentrations greater or equal to 1 mmol/L gives falsely high results.
Day(s) Performed
Monday through Sunday
Report Available
1 dayPerforming Laboratory
Mayo Clinic Laboratories in Rochester