Serum immunofixation is a laboratory technique used to identify proteins, or antibodies, in blood.

How the Test is Performed

Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.

Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

Immunofixation uses antibodies to identify the types of proteins or antibodies separated by protein electrophoresis.

How to Prepare for the Test

There is no special preparation for this test.

How the Test Will Feel

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the Test is Performed

This test is most often used to check the levels of certain antibodies associated with multiple myeloma and Waldenstrom's macroglobulinemia.Those antibodies include IgG, IgM, IgA, lambda light chain forms, and kappa light chain forms.

Immunofixation has also been used to study changes in protein structure (for example, glucose-6-phosphate dehydrogenase), and in the genetic typing of alpha-1 antitrypsin.

Normal Results

Monoclonal immunoglobulins are not present.

What Abnormal Results Mean

The presence of monoclonal proteins may indicate:

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

Risks

There is very little risk involved with having your blood taken. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

• Excessive bleeding
• Fainting or feeling lightheaded
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)