The primary blood test for Wilson's disease measures ceruloplasmin levels.
Ceruloplasmin is a protein in the blood that binds and transports copper. In Wilson's disease, the body's ability to process copper is impaired, leading to copper accumulation in the liver, brain, and other organs. This often results in low levels of ceruloplasmin in the blood. However, it's important to note that low ceruloplasmin doesn't always indicate Wilson's disease, and normal levels don't always rule it out.
Here's a more detailed breakdown:
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Ceruloplasmin Test: This is the most common initial blood test. Lower-than-normal levels raise suspicion for Wilson's disease.
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Serum Copper Test: Measures the total copper level in the blood. This test is often interpreted alongside the ceruloplasmin test. Although total copper levels may be lower than normal, free copper levels are elevated.
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24-Hour Urine Copper Test: Although not strictly a blood test, this urine test is often performed in conjunction with the blood tests to measure the amount of copper excreted in the urine over a 24-hour period. Patients with Wilson's disease typically excrete higher levels of copper in their urine.
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Other Blood Tests: Liver function tests are often performed to assess liver damage, which is common in Wilson's disease. These include tests like alanine aminotransferase (ALT) and aspartate aminotransferase (AST).
Important Considerations:
- A low ceruloplasmin level can also be caused by other conditions besides Wilson's disease, such as malnutrition, Menkes disease, or nephrotic syndrome.
- Some individuals with Wilson's disease may have ceruloplasmin levels within the normal range, especially if they have liver inflammation.
- Genetic testing is often performed to confirm the diagnosis of Wilson's disease, especially if blood test results are inconclusive.
- A liver biopsy may be necessary to confirm the diagnosis and assess the extent of liver damage.
In summary, while ceruloplasmin is the primary blood test used, diagnosis of Wilson's disease typically requires a combination of blood tests, urine tests, a physical examination, and potentially genetic testing or a liver biopsy.
