What Is Urine Immunofixation?

Medically Reviewed by Carmelita Swiner, MD on July 07, 2023
Written by WebMD Editorial Contributors
4 min read

Urine immunofixation is a test that measures proteins in your urine. It specifically looks for monoclonal protein, or M-protein, which shouldn’t be there in most cases.‌

Doctors will be able to find out if you have conditions such as multiple myeloma or primary amyloidosis through urine immunofixation. Read on to learn more about this test, what it can tell you, and more.

Urine immunofixation is a test that looks for abnormal proteins in urine. In particular, it looks for an abnormal protein known as M-protein.

An M-protein is a kind of abnormal immunoglobulin created by plasma cells, which are a type of white blood cells. Immunoglobulins are antibodies created and used by your body to destroy invaders such as viruses and bacteria.‌

M-proteins in your urine can be a sign of serious health problems, such as multiple myeloma.‌

Urine immunofixation uses electricity to push proteins from your urine sample through a kind of gel. This process is known as electrophoresis. The lab will also treat the gel so that it only keeps certain proteins in a process known as immunofixation. After this, the lab will do a stain test to see what kinds of proteins show up as bands or peaks.

Urine immunofixation typically requires a 24-hour urine sample.‌

You don’t need to do anything to prepare for this test, but you should tell your doctor about your medical history and all the medications, herbs, supplements, and vitamins you’ve been taking before you collect your urine. 

Be sure to include any illegal drugs and over-the-counter (not prescribed) medicine that you’re using. It is very important to be honest and upfront with this information. Your doctor needs to know what to expect in your urine in order to get the best test results.‌

Follow these steps to gather a 24-hour urine sample:‌

  1. Tell your healthcare provider if you’re pregnant or think you may be.
  2. Tell your healthcare provider about any medications, herbs, and supplements you’re taking.
  3. Prepare a cold place to store the urine while collecting it, such as a refrigerator.
  4. Choose a 24-hour period to do the urine collection at home, so you won’t have to move your urine from place to place.
  5. When gathering the urine samples, don’t use the urine from the first time you urinate. Flush this and note the time, since this will be the starting point of the 24-hour collection.
  6. All urine samples collected in the next 24 hours must be saved and stored in a cold place.
  7. 24 hours after the start time, try urinating to finish the process. However, it’s alright if you can’t.
  8. Once the collection process is finished, take the urine containers to the lab as soon as possible.

You should take this test if your doctor believes you have a health condition such as:

Primary amyloidosis. This is what it is called when an abnormal protein builds up in cells and organs. This tissue is known as amyloid and is made of antibody protein. Amyloid can damage organs such as your brain, lungs, heart, and kidneys by gathering in them.‌

Multiple myeloma. This is a type of cancer that forms in white blood cells known as plasma cells. As abnormal plasma cells build up in your bone marrow, you may grow bone tumors. 

Multiple myeloma prevents your bone marrow from making different blood cells. Symptoms include:

  • Shortness of breath
  • Fatigue or extreme exhaustion
  • Unusual bruising or bleeding
  • Bone pain
  • Unusual bone fractures

Waldenstrom macroglobulinemia. This is another type of cancer that begins in your white blood cells. It causes your bone marrow to produce too many white blood cells, leading to the production of a protein that accumulates in your blood. 

This will impact your blood circulation and cause complications. Symptoms include:

  • Weight loss
  • Unusual bruises or bleeding
  • Weakness and fatigue

Test results may be different depending on your gender, age, medical history, and other factors. Make sure to talk to your doctor to get a better understanding of your test results.‌

Normal Results. A normal result would mean you have no M-proteins in your urine.

Abnormal Results. This means you have M-proteins in your urine. This may indicate you have the conditions discussed above. Talk to your doctor to get a better understanding of what this could mean for your health and what you can do about it.

In addition to getting urine immunofixation, your doctor may also recommend you the following tests to see if you have a health condition:

  • X-rays to get a better view of your bones
  • Urine test to check for protein levels
  • Complete blood count (CBC) to measure the number of different cells in your blood
  • CT scans that will give the doctor a good look at your liver, spleen, and lymph nodes
  • Measurement of immunoglobulin levels in your blood
  • Analysis of a bone marrow sample

Your doctor may also order a biopsy of tissue from your body to check for amyloidosis.