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Copper - Deficiency Test

The copper test measures the urine level of copper, an essential trace element and a component of several metalloenzymes and proteins necessary for hemoglobin synthesis and oxidation reduction. Most copper in plasma is bound to and transported by an alpha2 globulin (plasma protein) called ceruloplasmin. When copper is unbound, the ions can inhibit many enzyme reactions, resulting in copper toxicity. Urine normally contains only a small amount of free copper

Determination of urine copper levels is frequently used to detect Wilson's disease, a rare, inborn metabolic error that is most common among people of ellstern European Jewish, southern Italian, or Sicilian ancestry.

Purpose

• To help detect Wilson's disease
• To screen infants with family histories of Wilson's disease

Patient preparation

• Explain to the patient that this test determines the amount of copper in urine.
• Inform him that no special restrictions are necessary.
• Tell him the test requires urine collection over a 24-hour period. If the specimen is to be collected at home, describe the proper collection technique.

Procedure and posttest care

• Collect the patient's urine over a 24hour period.
• Refrigerate the specimen during the collection period.

Precautions

• Tell the patient not to contaminate the urine specimen with toilet tissue or stool.

Reference values

Normal urinary excretion of copper is 15 to 60 ug/24 hours.

Abnormal findings

Elevated urine copper levels usually indicate Wilson's disease (a liver biopsy helps establish this diagnosis). Wilson's disease is marked by decreased ceruloplasmin, increased urinary excretion of copper, and accumulation of copper in the interstitial tissues of the liver and brain. Early detection and treatment (low-copper diet and Dpenicillamine) are vital to prevent irreversible changes, such as nerve tissue degeneration and cirrhosis of the liver.

Elevated copper levels may also occur in nephrotic syndromes, chronic active hepatitis, biliary cirrhosis, rheumatoid arthritis, chelation therapy, and estrogen therapy.

Interfering factors

• Contamination of the specimen with toilet tissue or stool
• Failure to refrigerate specimen