概述
A Bence Jones protein test is a urine test that looks for Bence Jones protein. Your healthcare team may order it with other tests to evaluate possible plasma cell disorders.
The test also may be called:
- Bence Jones urine.
- Urine light chain testing.
- Urine immunofixation.
- Urine protein electrophoresis.
The exact name depends on the testing method the lab uses.
A kappa and lambda free light chain test is related, but it is a different test that measures light chains in blood. Your care team may use blood and urine tests together because they give different information.
Bence Jones protein is a monoclonal free light chain found in urine. Monoclonal proteins (M proteins) are antibody proteins made by one group of plasma cells. An M-protein can be a whole antibody or part of an antibody. Antibodies help your immune system recognize and fight germs.
Light chains are parts of antibodies. They attach to heavy chains to make up part of an antibody.
A light chain is free if it isn't attached to a heavy chain. There are two types of light chains: kappa and lambda. A Bence Jones protein can be either type.
Kidneys filter free light chains from the blood. But if plasma cells make too much of one type of free light chain, the kidneys may not be able to filter the extra.
The extra monoclonal light chains can then pass into the urine as Bence Jones protein.
目的
Your care team may order a Bence Jones protein test to look for or monitor a monoclonal gammopathy. The condition occurs when one group of cells makes copies of the same M protein.
Conditions linked with monoclonal light chains in urine include:
A Bence Jones protein test finds protein in urine. It doesn't find tumors. A positive result doesn't, by itself, mean that you have multiple myeloma or another cancer. Bence Jones protein can be found in people with MGUS and other conditions.
A Bence Jones protein test also can help your care team check whether an M protein is affecting the kidneys. Monoclonal light chains can damage kidney structures or build up in them. This test is not a general test for every type of kidney disease.
To understand your specific condition, your care team may order a Bence Jones protein test with other tests, such as a kappa and lambda free light chain test or serum protein electrophoresis.
风险
Collecting a urine sample usually has no serious risks and causes little or no physical discomfort.
如何进行准备
There are two types of urine tests: random and 24-hour. A random urine sample is a one urine sample collected at any time of day. It can show whether a monoclonal protein is present. A 24-hour sample collects all urine over 24 hours. It may be preferred if your care team needs to measure the amount of M protein or follow it over time. Your care team or lab can tell you which type of sample you will need.
You usually do not need to change what you eat or drink before collecting the urine sample.
可能出现的情况
During the procedure
For a random test, you may provide one sample at the lab. For a 24-hour collection, you collect urine over a full 24 hours in a container provided by the lab. Your lab may recommend keeping the sample refrigerated during the collection. Follow the collection instructions from your care team or lab.
After the procedure
After collection, the urine sample goes to the lab for testing. Results may be ready in 4 to 6 days, depending on the lab and type of test.
结果
Depending on the test, your report may include:
- Whether a Bence Jones monoclonal protein was found.
- Whether the light chain is kappa or lambda.
- How much protein was measured.
What a positive result may mean
People don't typically have Bence Jones protein in their urine. A positive test means the protein was found. The result may identify whether the Bence Jones protein is a kappa or lambda light chain.
A positive result does not identify one disease by itself. Bence Jones protein may occur with a range of conditions. Your care team looks at the test result with other test results and your medical information to make a diagnosis.
What a negative result may mean
A negative result means the test did not find Bence Jones protein in the urine sample. A negative result does not rule out monoclonal gammopathy.
The Bence Jones protein test result is often only one part of an evaluation. Your care team also may use blood and other urine tests to learn more about M proteins in the body.
What happens next
Your care team may compare your urine test result with blood tests and earlier results. Your team also may repeat Bence Jones protein testing over time to monitor some monoclonal gammopathies or see how treatment is working. How often you need testing may depend on why your care team ordered the test.
Aug. 22, 2026