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Test ID: CUCRU Copper/Creatinine Ratio, Random, Urine

Reporting Name

Copper/Creat Ratio, Random, U

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
CUCR Copper/Creat Ratio, U No Yes
CDCR Creatinine Conc No Yes

Specimen Type

Urine


Specimen Required


Patient Preparation: High concentrations of barium are known to interfere with most metals tests. If barium-containing contrast media has been administered, a 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 Trace Metals Analysis Specimen Collection and Transport in Special Instructions for complete instructions.


Specimen Minimum Volume

0.7 mL

Specimen Stability Information

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

Reference Values

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

Day(s) and Time(s) Performed

Monday; Continuously

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

82525-Copper Concentration

82570-Creatinine Concentration

LOINC Code Information

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

 

Result ID Test Result Name Result LOINC Value
CDCR Creatinine Conc 2161-8
32872 Copper/Creat Ratio, U 13829-7

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 in patients taking contraceptives or estrogens and during pregnancy.

 

Low urine copper levels are seen in malnutrition, hypoproteinemias, malabsorption, and nephrotic syndrome. Increased zinc consumption interferes with normal copper absorption from the gastrointestinal tract causing hypocupremia.

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.

Clinical Reference

1. Zorbas YG, Kakuris KK, Deogenov VA, Yerullis KB: Copper homeostasis during hypokinesia in healthy subjects with higher and lower copper consumption. Tr Elem Electro. 2008;25:169-178

2. Lech T, Sadlik JK: Contribution to the data on copper concentration in blood and urine in patients with Wilson's disease and in normal subjects. Biol Trace Elem Res. 2007 Jul;118(1):16-20

3. Rifai N, Horwath AR, Wittwer CT, eds: Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018

Analytic Time

1 day

Method Name

CUCR: Inductively Coupled Plasma-Mass Spectrometry (ICP-MS)

CDCR: Enzymatic Colorimetric Assay

Forms

If not ordering electronically, complete, print, and send a Gastroenterology and Hepatology Client Test Request (T728) with the specimen.

Mayo Clinic Laboratories | Gastroenterology Catalog Additional Information:

mml-gi-liver-genetic