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Test Code CURCU Copper/Creatinine Ratio, Random, Urine


Specimen Required


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

Investigation of Wilson disease and obstructive liver disease using a random urine specimen

Profile Information

Test ID Reporting Name Available Separately Always Performed
CURC Copper/Creat Ratio, U No Yes
CRETR Creatinine, Random, U No Yes

Method Name

CURC: Triple-Quadrupole Inductively-Coupled Plasma Mass Spectrometry (ICP-MS/MS)

CRETR: Enzymatic Colorimetric Assay

Reporting Name

Copper/Creat Ratio, Random, U

Specimen Type

Urine

Specimen Minimum Volume

2 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Urine Refrigerated (preferred) 28 days
  Frozen  28 days
  Ambient  14 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

COPPER/CREATITINE:

Males:

0-17 years: Not established

≥18 years: 9-43 mcg/g creatinine

Females:

0-17 years: Not established

≥18 years: 7-72 mcg/g creatinine

 

CREATITINE:

≥18 years old: 16-326 mg/dL

Reference values have not been established for patients who are younger than 18 years.

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.

Day(s) Performed

Monday, Thursday

Report Available

2 to 5 days

Specimen Retention Time

14 days

Performing 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

82570

LOINC Code Information

Test ID Test Order Name Order LOINC Value
CURCU Copper/Creat Ratio, Random, U 13829-7

 

Result ID Test Result Name Result LOINC Value
615258 Copper/Creat Ratio, U 13829-7
CRETR Creatinine, Random, U 2161-8