What causes Bence Jones protein in urine?
The Bence Jones protein is a building block of the antibodies made by cancerous tumors, so detecting it can help doctors diagnose types of cancer. Learn more about the test and results in this article.
What is the Bence Jones protein test?
The Bence Jones protein test will be used if a doctor suspects multiple myeloma.
The Bence Jones protein urine test is one of many tests that doctors can do if they suspect that someone has multiple myeloma, which is a form of blood cancer.
Healthy urine does not contain Bence Jones protein, so its presence is an indication of a health problem.
Other names for this test include urine protein electrophoresis (UPEP), urine immunofixation electrophoresis, or immunoassay for free light chains.
Why is it used?
The main use of the Bence Jones protein urine test is to diagnose and monitor multiple myeloma.
Multiple myeloma happens when the plasma cells, which make the antibodies that fight infection, start to multiply uncontrollably and release Bence Jones protein. This protein does not serve any useful function in the body.
Multiple myeloma can cause the following blood problems:
- Anemia: A shortage of red blood cells that can lead to weakness and exhaustion.
- Thrombocytopenia: A shortage of thrombocytes or blood platelets that help the blood clot. This may cause excessive bleeding or bruising.
- Leukopenia: A shortage of white blood cells, which can weaken the immune system.
Doctors have also linked the Bence Jones protein to cancers of the lymphatic system, including lymphoma and Waldenstrom macroglobulinemia.
Who has a Bence Jones protein test?
A person may be sent for a Bence Jones protein urine test if their doctor suspects they might have multiple myeloma.
The symptoms may include:
- bone pain or fracturing, particularly in the back, hips, or skull
- confusion and or dizziness
- weakness and swelling in the legs
- multiple infections
A doctor will also look for other indicators of multiple myeloma, including:
- high levels of calcium in the blood
- low levels of red or white blood cells in the blood
- low levels of platelets in the blood
How is it done?
Urine is collected over a 24 hour period and a laboratory checks for the presence of the Bence Jones protein.
The Bence Jones protein urine test is a 24-hour test. A person will need to collect all the urine they pass over a 24-hour period, as the components of urine change over the course of the day.
The healthcare team will provide a container for collection. The sample will need to be kept cool and may need to be refrigerated, depending on local weather conditions.
A person should not collect the first urine they pass on the day of the test. However, all urine passed for the next 24 hours should be collected and added to the container. A person may also be asked to write down the time each sample is collected.
The laboratory will then check the complete sample for the presence of Bence Jones protein.
It is essential for a person to let their doctor know about any medications, supplements, or vitamins they are taking, as these may affect the results.
What do the results mean?
Ordinarily, healthy urine does not contain Bence Jones protein. However, the results can vary between individuals, and many other tests are taken into account before a doctor makes a diagnosis.
Bence Jones protein may also present in a condition called monoclonal gammopathy of undetermined significance (MGUS).
MGUS refers to when plasma cells make more of one kind of protein found in white blood cells than they should but do not form a tumor or otherwise damage the body. However, if this condition progresses, it can lead to diseases such as blood cancers.
Nevertheless, high levels of the Bence Jones protein can indicate multiple myeloma. The protein has also been linked to other types of cancer, such as lymphoma and Waldenstrom macroglobulinemia.
Doctors may diagnose smouldering myeloma if they find Bence Jones protein but blood tests show normal blood counts, calcium levels, and kidney function.
Smouldering myeloma is early-stage myeloma. It does not cause symptoms but will still be monitored.
The diagnosis an individual receives after a Bence Jones protein test will determine their outlook.
While it does not usually need treatment, MGUS does place people at a higher risk of developing multiple myeloma and lymphoma.
They may also be at risk of amyloidosis, which is a buildup of certain proteins in tissues. As such, long-term monitoring is usually advised.
Likewise, anyone with smouldering myeloma will also require long-term monitoring.
If multiple myeloma is diagnosed, a Bence-Jones protein urine level can be used in conjunction with other tests to determine the stage of someone's cancer. This information will inform treatment options and the long-term outlook.