Bence-Jones Protein (Urine)
Does this test have other names?
Urine protein electrophoresis, immunofixation electrophoresis, immunoassay for free light chains
What is this test?
The Bence-Jones protein urine test is used mainly to diagnose and monitor multiple myeloma, a blood cancer. An abnormal Bence-Jones test result is also linked with malignant lymphomas, which are cancers of the lymphatic system.
Multiple myeloma is a cancer of the plasma cells. These are immune system cells that produce specialized molecules called antibodies to help fight infectious germs. Because most plasma cells live in bone marrow, multiple myeloma tumors are usually, but not always, found in bone.
The bone marrow is where blood cells are produced. Because multiple myeloma crowds out bone marrow, it can cause several kinds of blood deficiencies:
Anemia, a shortage of red blood cells, which can lead to weakness and exhaustion
Thrombocytopenia, a shortage of blood platelets called thrombocytes, which are necessary for forming blood clots. This condition therefore causes excessive bleeding or bruising.
Leukopenia, a shortage of white blood cells that can lead to a weakening of the immune system
Healthy plasma cells are one kind of blood cell that can be crowded out by multiple myeloma. Instead of a variety of plasma cells producing antibodies to fight a variety of infections, myeloma tumors produce "monoclonal" antibodies. Monoclonal means they are all of one kind, making them ineffective and even harmful. Not only do they not fight infections, but they also can damage the kidneys. These monoclonal proteins are made up of two light chains and two heavy chains. Bence-Jones proteins are the light chain part of these monoclonal antibodies. They show up in the urine in many of cases of multiple myeloma.
Myeloma cells also produce chemical signals that tell osteoclasts, or cells that break down bone, to work overtime. Multiple myeloma can thus weaken bones and lead to fractures. The breakdown of bone material can also lead to higher-than-normal levels of calcium in the blood. High blood calcium, a condition called hypercalcemia, can cause many problems. These range from excessive thirst and urination to dehydration, kidney problems, and, in extreme cases, coma.
Why do I need this test?
You might have a Bence-Jones protein test and other procedures to check for multiple myeloma if you have some of these symptoms:
Bone pain, or even fracturing, especially in the back, hips, or skull
High blood calcium, likely caused by the breakdown of bone
Low counts of red or white blood cells or platelets in the blood
Nervous system problems, including pain, numbness, or weakness. These can be caused by bones deteriorating and pinching nerves or by myeloma-produced toxins that damage nerves.
Stroke-like symptoms, confusion, and dizziness. These symptoms should be brought to a doctor's attention immediately. They can also be symptoms of multiple myeloma because the myeloma cells sometimes produce chemicals that cause the blood to become thicker. This can limit blood flow to the brain.
Weakness and swelling of the legs, which can be caused by kidney damage resulting from myeloma
An increased vulnerability to infections, which may stem from myeloma's impact on the immune system
What other tests might I have along with this test?
The investigation of multiple myeloma often requires a variety of tests. In addition to the test to check for Bence-Jones proteins in your urine, a health care provider may order blood tests and also tests on bone and bone marrow. Possible blood tests include:
Complete blood count, or CBC. This checks the numbers of red blood cells, white blood cells, and platelets in the blood.
Chemistry profile. This checks your levels of albumin, blood urea nitrogen, calcium, creatinine, and lactate dehydrogenase. These levels can provide doctors with information about kidney function and the extent to which multiple myeloma has spread.
Beta-2 microglobulin and C-reactive protein. The levels of these proteins help find out how multiple myeloma has spread.
Quantitative immunoglobulin testing. This checks levels of various kinds of antibodies.
Serum protein electrophoresis, or SPEP. This checks the levels of various proteins in the blood. In particular, this test can detect the presence of "M protein," another name for the large number of abnormal monoclonal antibodies being produced.
Immunofixation electrophoresis, or IFE. This test also looks at proteins that come from abnormal antibodies.
Possible tests on bone and bone marrow include:
X-rays can be used to check for bone damage. Other imaging techniques, such as MRI, CT, and/or PET, may be used to look at bones for damage and also to see the number and size of myeloma tumors.
A bone marrow sample may be taken so that the cells in the marrow can be directly looked at for multiple myeloma.
What do my test results mean?
Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.
You usually have no Bence-Jones proteins in your urine. The presence of Bence-Jones proteins in urine can be a sign of multiple myeloma or another rare condition called Waldenstrom's macroglobulinemia. Approximately 50 to 80 percent of people with multiple myeloma have Bence-Jones proteins in their urine.
This protein can also be present if you have monoclonal gammopathy of undetermined significance, or MGUS. In this condition, your plasma cells produce more of one kind of antibody than they should, but they don't form a tumor or make enough antibodies to do damage. MGUS doesn't generally require treatment, but if you have MGUS, you are at higher risk of developing multiple myeloma. You are also at higher risk for lymphoma, a cancer affecting white blood cells, or amyloidosis, the buildup of certain proteins in tissues. For these reasons, you should be watched by a doctor.
If you have been diagnosed with multiple myeloma, a Bence-Jones protein urine level can also be used as one of several ways to find out the stage of the cancer. That is, how far it has progressed. The other factors used in staging are your calcium level, hemoglobin level, and X-ray findings.
The Bence-Jones proteins are also found in some people with lymphoma.
How is this test done?
The lab may measure the amount of Bence-Jones protein in a 24-hour urine sample. To do this test, you will need to collect all the urine you pass during a 24-hour period. You will collect it in a container that your doctor or the lab gives you.
Urine protein electrophoresis, or UPEP, tests the levels of various proteins in the urine, including Bence-Jones proteins. This test does not require a 24-hour sample, just a small sample placed in a collection cup at the lab.
What might affect my test results?
If your doctor uses a test strip to look for Bence-Jones proteins, it may not detect them. The best way to find these proteins is to use electrophoresis or an immunoassay. Also, talk with your doctor to find out whether any of the medications you are taking might affect your test results.
How do I get ready for this test?
You don't need to prepare for this test.