What Is the Immunofixation Urine Test?

Protein in the urine can be a sign of serious health complications. The kidneys are responsible for filtering waste products and extra fluid out of the blood and into the urine, while leaving proteins in the blood. However, proteins are filtered out of the blood with waste products and show up in the urine when the filtering process is impaired.

Various diagnostic tests can be used to determine the type and the amount of protein in the urine. The test results will help your doctor determine an appropriate diagnosis and treatment.

The immunofixation-urine test or urine immunofixation test is used to detect the presence and measure the amount of certain types of proteins in the urine. These proteins are called immunoglobulins. They are broadly classified as normal or abnormal.

Abnormal immunoglobulins in the urine suggest the presence of disease. An example of an abnormal immunoglobulin is monoclonal protein or M protein.

Why Is the Test Ordered?

The immunofixation-urine test is typically ordered when a doctor suspects an individual may have certain health conditions, including multiple myeloma and Waldenstrom’s macroglobulinemia. These disorders produce abnormal immunoglobulins that can be detected in the urine.

Symptoms of multiple myeloma include:

  • increased bruising and bleeding of the gums or from the nose
  • fatigue, paleness, and shortness of breath due to anemia
  • fevers of unknown origin and repeated infections
  • bone pain, especially in the spine, ribs, skull, and pelvis
  • unexplained bone damage and fractures
  • symptoms of high levels of calcium in the blood, including muscle aches/weakness, joint pain, heart arrhythmias, constipation, nausea, vomiting, and changes in mental status

Symptoms of Waldenstrom’s macroglobulinemia include:

  • bleeding of the gums
  • blurred vision
  • dizziness
  • fatigue
  • easy bruising of the skin
  • headache
  • changes in mental status
  • numbness or tingling in the hands or feet
  • unexplained rash

The immunofixation-urine test is often used as a screening measure to evaluate abnormal immunoglobulin levels because the results are available more quickly than they would be with other tests.

Similar results can be obtained from the immunoelectrophoresis-serum (IEP-serum) test. It may take longer to obtain results from the IEP-serum test. However, the results may be more accurate.

How Is the Test Administered?

The immunofixation-urine test is administered in a healthcare setting. You will be required to provide a midstream, clean-catch urine sample. This method will help prevent germs that may be around or in the urethra from entering the sample container.

Your doctor or nurse will supply you with a clean-catch urine kit. The kit will include sterile towels for cleaning and a sterile-catch container with a lid. Men or boys must first clean the head of the penis using the sterile towels. Women and girls must use the sterile towels to wash the area between the lips of the vulva.

Once you have carefully cleaned yourself, you will urinate a small amount into the toilet bowl and then stop the flow of urine. This will clear the urethra of contaminants. Then you will collect the remaining urine in the sterile cup. The total volume of the urine sample should be 1 to 2 ounces.

Once the sample has been collected, you will place the lid on the cup and either leave it in a box marked for samples or take it to your doctor or nurse. The individual who gave you the clean-catch kit will tell you what to do with the sample. The doctor or nurse will then send the urine sample to the lab for evaluation.

The clean-catch urine procedure can be awkward, and you may find your first sample is less than the required 1 to 2 ounces. This is not unusual. You can complete more than one clean-catch procedure to acquire the needed sample volume.

You must ask for a new sterile clean-catch kit for each attempt to collect urine. The sterile towels and containers cannot be reused. Repeat all the steps of the clean-catch urine procedure as you collect more urine.

The immunofixation-urine test requires only normal urination. The test is not invasive and does not pose any significant risks to the patient. The test should not produce any discomfort.

Understanding Your Results

A negative result from the test indicates that there are no abnormal immunoglobulins present in the urine. If abnormal immunoglobulins are not detected, you may not be required to undergo any additional testing.

Abnormal immunoglobulins may suggest the presence of a serious health issue such as multiple myeloma or Waldenstrom’s macroglobulinemia. The presence of abnormal immunoglobulins also may be an indication of other types of cancer.

The immunofixation-urine test is only one of several diagnostic tests that will need to be completed to confirm your diagnosis. The detection of abnormal immunoglobulins may not indicate an underlying health condition for some patients. A small percentage of individuals have low levels of abnormal immunoglobulins in their bodies. These individuals do not develop any health problems. This condition is known as monoclonal gammopathy of unknown significance (MGUS).