Diagnosing Multiple Myeloma from Test Results

Although multiple myeloma is often diagnosed based on tests, the patient’s symptoms and the doctor’s physical examination of the patient are also important. A diagnosis of multiple myeloma requires either:

1. A plasma cell tumor (proven by biopsy) OR at least 10% of the cells in the bone marrow are plasma cells, AND at least one of the following:

  • High blood calcium level
  • Poor kidney function
  • Low red blood cell counts (anemia)
  • Holes in bones from tumor growth found on imaging studies
  • An abnormal area in the bones or bone marrow on an MRI scan
  • Increase in one type of light chains in the blood so that one type is 100 times more common than the other


2. 60% or more plasma cells in the bone marrow

Smoldering myeloma

This term is used to mean early myeloma that is not causing any symptoms or problems. People with smoldering myeloma have some signs of multiple myeloma, such as any of the following

  • Plasma cells in the bone marrow between 10 and 60%
  • High level of monoclonal immunoglobulin (M protein) in the blood
  • High level of light chains in the urine (also called Bence Jones protein)

But they have normal blood counts, normal calcium levels, normal kidney function, no bone or organ damage, and no signs of amyloidosis. Smoldering myeloma often does not need to be treated right away.

Light chain amyloidosis

A diagnosis of light chain amyloidosis is made when the patient has both:

  • Signs and symptoms of amyloidosis, and
  • A biopsy that shows amyloid made up of light chains,

PLUS any of the following:

  • Elevated free light chains in the blood,
  • Elevated light chains in the urine (also called Bence Jones protein),
  • Abnormal plasma cells in the bone marrow

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master's-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Last Medical Review: May 22, 2014 Last Revised: January 19, 2016

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