Multiple Myeloma Diagnosis

Multiple myeloma (MM) is diagnosed through a series of blood tests, x-rays, urinalysis and examination of bone marrow cells. MM produces distinct results on these tests, making diagnosis relatively straightforward once suspected.

Gel Electrophoresis: Blood Tests for IgA and IgG Antibodies

Blood tests that measure the level of white blood cells can return normal results even when multiple myeloma is present. A test called gel electrophoresis examines the blood for abnormal immunoglobulin levels: specifically, for high levels of IgA or IgG antibodies.

To conduct a gel electrophoresis test, a technician spreads a blood sample over agar gel and then applies an electrical current to the sample. This procedure separates proteins into distinct groups. The lab results may indicate a “spike” or overabundance of one immunoglobulin type. This spike is referred to as a monoclonal component, or simply M component.

Monoclonal immunoglobulins develop from a single abnormal cell type such as cancer cells.As the monoclonal immunoglobulins accumulate, the other, normal antibodies decrease in number. Normally, gel electrophoresis reveals a broad range of different antibodies, with a spike of albumin proteins. Test results indicating myeloma, however, show a high M component of IgA or IgG antibodies, and low levels of other immunoglobulins.


Urinalysis uses a test similar to gel electrophoresis that reveals an unusual spike of certain antibody fragments in the urine. These fragments are “light chain” portions of antibodies, which are also called Bence Jones proteins. More information about light chains and antibodies is available at Information on Amyloidosis.

Bone Marrow Samples

Examination of bone marrow samples taken from people with multiple myeloma reveals an overabundance of plasma cells, the white blood cells that produce antibodies. A bone marrow sample that contains over ten percent of plasma cells is a strong indicator of MM.

X-rays and Diagnostic Tools

X-rays and other diagnostic tools, such as CT scans and MRIs, help determine the spread and location of the myelomas. X-rays may reveal “punched out” bone lesions with sharp borders that are common in cases of multiple myeloma, as well as fractures and breaks caused by bone deterioration.

MGUS and Intermediate Myeloma

Sometimes test results reveal certain characteristics of multiple myeloma without other indications. A high M component without any other signs of myeloma indicates a condition known as monoclonal gammopathy of undetermined significance (MGUS). MGUS becomes more common with age, and usually requires no treatment. MGUS must be monitored, however, as up to 25 percent of individuals with the condition develop multiple myeloma later in life.

An intermediate form of the disease called smoldering multiple myeloma has a high M component and a plasma cell count over ten percent. No other clinical symptoms, and few bone lesions are evident. Smoldering multiple myeloma must be monitored carefully for signs that the condition is worsening.