Normalization of urinary analytes to account for the variation in urinary concentrations between individuals when using random urine collections
Only orderable as part of a profile. For more information see:
ALBR / Albumin, Random, Urine
RALB / Albumin, Random, Urine.
Enzymatic Colorimetric Assay
Urine
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.
1 mL
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability. |
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Urine | Refrigerated (preferred) | 30 days | |
Ambient | 30 days | ||
Frozen | 30 days |
Normalization of urinary analytes to account for the variation in urinary concentrations between individuals when using random urine collections
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.
Only orderable as part of a profile. For more information see:
ALBR / Albumin, Random, Urine
RALB / Albumin, Random, Urine.
Not applicable
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.
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.
1. Meeusen J, Rule A, Voskoboev N, Baumann N, Lieske J: Performance of cystatin C-creatinine-based estimated glomerular filtration rate equations depends on patient characteristics. Clin Chem. 2015 Oct;61(10):1265-1272. doi:10.1373/clinchem.2015.243030
2. Newman DJ, Price CP: Renal function and nitrogen metabolites. In: Burtis CA, Ashwood ER, eds. Tietz Textbook of Clinical Chemistry. 3rd ed. WB Saunders Company; 1999:1204-1270
3. Kasiske BL, Keane WF: Laboratory assessment of renal disease: clearance, urinalysis, and renal biopsy. In: Brenner BM, ed. The Kidney. 6th ed. WB Saunders Company; 2000:1129-1170
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)
Monday through Sunday
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.
82570
Test Id | Test Order Name | Order LOINC Value |
---|---|---|
CRE2 | Creatinine | 2161-8 |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
CRE2 | Creatinine | 2161-8 |