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HelpTest Code CURC Copper/Creatinine Ratio, Urine
Specimen Required
Only orderable as part of a profile. For more information see CURCU / Copper/Creatinine Ratio, Random, Urine.
Patient Preparation: High concentrations of barium are known to interfere with most metal tests. If barium-containing contrast media has been administered, the specimen should not be collected for at least 96 hours.
Supplies: Urine Tubes, 10 mL (T068)
Collection Container/Tube: Clean, plastic urine collection container with no metal cap or glued insert
Submission Container/Tube: Plastic, 10-mL urine tube or a clean, plastic aliquot container with no metal cap or glued insert
Specimen Volume: 3 mL
Collection Instructions:
1. Collect a random urine specimen.
2. See Metals Analysis Specimen Collection and Transport for complete instructions.
Useful For
Measurement of copper concentration of a part of the investigation of Wilson disease and obstructive liver disease using a random urine specimen
Method Name
Only orderable as part of a profile. For more information see CURCU / Copper/Creatinine Ratio, Random, Urine.
Inductively Coupled Plasma Mass Spectrometry (ICP-MS)
Reporting Name
Copper/Creat Ratio, USpecimen Type
UrineSpecimen Minimum Volume
2 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Refrigerated (preferred) | 28 days | |
| Ambient | 28 days | ||
| Frozen | 28 days |
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Clinical Information
The biliary system is the major pathway of copper excretion. Biliary excretion of copper requires an adenosine triphosphate (ATP)-dependent transporter protein. Variants in the gene for the transporter protein cause hepatolenticular degeneration (Wilson disease). Ceruloplasmin, the primary copper-carrying protein in the blood, is also reduced in Wilson disease. Urine copper excretion is increased in Wilson disease due to a decreased serum binding of copper to ceruloplasmin or due to allelic variances in cellular metal ion transporters.
Hypercupriuria (increased urinary copper) is also found in hemochromatosis, biliary cirrhosis, thyrotoxicosis, various infections, and a variety of other acute, chronic, and malignant diseases (including leukemia). Urine copper concentrations are also elevated during pregnancy and in patients taking contraceptives or estrogens.
Low urine copper levels are seen in malnutrition, hypoproteinemia, malabsorption, and nephrotic syndrome. Increased zinc consumption interferes with normal copper absorption from the gastrointestinal tract causing hypocupremia.
Reference Values
Only orderable as part of a profile. For more information see CURCU / Copper/Creatinine Ratio, Random, Urine.
Not applicable
Interpretation
Humans normally excrete less than 60 mcg/24 hour in the urine.
Urinary copper excretion greater than 60 mcg/24 hour may be seen in:
-Wilson disease
-Obstructive biliary disease (eg, primary biliary cirrhosis, primary sclerosing cholangitis)
-Nephrotic syndrome (due to leakage through the kidney)
-Chelation therapy
-Estrogen therapy
-Mega dosing of zinc-containing vitamins
Because ceruloplasmin is an acute phase reactant, urine copper is elevated during acute inflammation. During the recovery phase, urine copper is usually below normal, reflecting the expected physiologic response to replace the copper that was depleted during inflammation.
Cautions
No significant cautionary statements
Day(s) Performed
Monday, Thursday
Report Available
2 to 5 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
82525
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| CURC | Copper/Creat Ratio, U | 13829-7 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 615258 | Copper/Creat Ratio, U | 13829-7 |