What Is an 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, when the filtering process isn’t functioning properly, the body filters these proteins out of the blood and into the urine.

Various diagnostic tests can 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 detects the presence and measures the amount of certain types of proteins in the urine. These proteins are known as immunoglobulins. They fall into two broad classifications: normal or abnormal.

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

The immunofixation urine test is a common test used when a doctor suspects an individual may have certain health conditions, including multiple myeloma and Waldenstrom’s macroglobulinemia. These disorders produce abnormal immunoglobulins that the immunofixation urine test can detect 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 a common screening measure to evaluate abnormal immunoglobulin levels because the results are available more quickly than they would be with other tests.

The immunoelectrophoresis-serum (IEP-serum) test provides similar results. It may take longer to obtain results from the IEP-serum test. However, the results may be more accurate.

The immunofixation urine test occurs in a healthcare setting. You will need to provide a midstream, clean-catch urine sample. This method will help prevent germs that may be near 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. If you are male, you must first clean the head of the penis using the sterile towels. If you are female, use the sterile towels to wash the area between the lips of the vulva.

After carefully cleaning 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 between one and two ounces.

When you finish collecting the sample, 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 one to two ounces. This isn’t 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. You can’t reuse the sterile towels and containers. 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 isn’t invasive and doesn’t pose any significant risks to the patient. The test shouldn’t produce any discomfort.

A negative result from the test indicates that there are no abnormal immunoglobulins present in the urine. If the test doesn’t detect abnormal immunoglobulins, you may not need to undergo any additional testing.

A positive result means that abnormal immunoglobulins were present in your urine Abnormal immunoglobulins may suggest 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 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 don’t develop any health problems. This condition is known as monoclonal gammopathy of unknown significance (MGUS).