Immunofixation - urine

Definition

Urine immunofixation is a laboratory technique used to identify proteins in urine.

See also: Immunofixation - blood

Alternative Names

How the test is performed

A clean-catch (midstream) urine sample is needed.

Men or boys should first wipe clean the head of the penis. Women or girls need to wash the area between the lips of the vagina 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.

For an infant, thoroughly wash the area where the urine leaves the body. Open a urine collection bag (a plastic bag with an adhesive paper on one end). For males, place the entire penis in the bag and attach the adhesive to the skin. For females, place the bag over the labia. Diaper as usual over the secured bag.

This procedure may take a couple of attempts -- lively infants can move the bag, causing the urine to be absorbed by the diaper. Check the infant frequently and change the bag after the infant has urinated into it. Drain the urine from the bag into the container provided by your health care provider.

Deliver it to the laboratory or your health care provider as soon as possible upon completion.

How to prepare for the test

No special preparation is necessary for this test.

How the test will feel

The test involves only normal urination. There is no discomfort.

Why the test is performed

This test is most often used to check the levels of certain proteins (called monoclonal immunoglobulins) associated with multiple myeloma and Waldenstrom's macroglobulinemia.

Normal Values

No presence of monoclonal immunoglobulins is normal.

What abnormal results mean

The presence of monoclonal proteins may indicate:

• Immune system disorders such as multiple myeloma or Waldenstrom's macroglobulinemia
• Cancer

What the risks are

Special considerations

Immunofixation is similar to urine immunoelectrophoresis, but it may give more rapid results.

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References

McPherson RA and Pincus MR. Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. Philadelphia, Pa: WB Saunders; 2007:845-6.

Hoffman R, Benz Jr. EJ, Shattil SJ, et al., eds. Hematology: Basic Principles and Practice. 4th ed. Philadelphia, Pa: Churchill Livingston; 2005:727-33.