Definition
This test measures the presence of Bence-Jones proteins (free immunoglobulin light chains) in urine.
Normally, light chains (one component of antibodies) are produced in excess of heavy chains (the other component of antibodies). Increases in free light chains (polyclonal) may occur with increased immunoglobulin synthesis or catabolism (breakdown of cells and tissues).
These light chains do not exhibit the same characteristics of Bence-Jones proteins (monoclonal free-light chains). Immunofixation is the best test for detecting free monoclonal light chains.
Alternative Names
Immunoglobulin light chains - urine; Urine Bence-Jones protein
Why the Test is Performed
This test is performed to aid in the diagnosis of disorders that can cause
protein in the urine (
proteinuria).
How the Test is Performed
Collect a "clean-catch" (midstream) urine sample. To obtain a clean-catch sample, men or boys should wipe clean the head of the penis. Women or girls should wash the area between the labia with soapy water and rinse well. As you start to urinate, allow a small amount to fall into the toilet bowl. (This clears the urethra of contaminants.) Then, in a clean container, catch about 1 to 2 ounces of urine, and remove the container from the urine stream. Give the container to the health care provider or assistant.
Infant:
Thoroughly wash the area around the urethra. Open a urine collection bag (a plastic bag with an adhesive paper on one end), and place it on your infant. For males, the entire penis can be placed in the bag and the adhesive attached to the skin. For females, the bag is placed over the labia. Place a diaper over the infant (bag and all). Check your baby frequently and remove the bag after the infant has urinated into it. For active infants, this procedure may take a couple of attempts -- lively infants can displace the bag, causing an inability to obtain the specimen. The urine is drained into a container for transport back to the health care provider
Since Bence-Jones proteins are relatively small, they can be filtered by the glomerulus (blood filtering unit of the kidney). When urine protein is elevated, and other clinical features suggest multiple myeloma, a Bence-Jones proteins test may be ordered. These proteins have an unusual thermal property that allows them to be identified. They precipitate from urine when heated to between 113 degrees and 140 degrees Fahrenheit and then re-dissolve on boiling. Definitive identification is made by immunoelectrophoresis.
How to Prepare for the Test
Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:
How the Test Will Feel
The test involves only normal urination, and there is no discomfort.
Normal Results
No presence of Bence-Jones proteins is normal.
What Abnormal Results Mean
Bence-Jones proteins are a rare finding in urine, but if present, they are usually associated with
multiple myeloma. Less commonly they are in
Waldenstrom's macroglobulinemia,
chronic lymphocytic leukemia, or
amyloidosis.
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