How is multiple myeloma diagnosed?

This page was reviewed under our medical and editorial policy by

Maurie Markman, MD, President, Medicine & Science

This page was updated on December 13, 2022.

Multiple myeloma, also referred to as bone marrow cancer, is often difficult to diagnose, and may require several different tests to analyze. Before the cancer care team reaches a diagnosis of multiple myeloma, they'll perform a physical exam, get the patient's medical history, then order diagnostic tests that help them better evaluate the patient's condition.

Diagnostic tests for multiple myeloma

Tests designed for diagnosing multiple myeloma include:


A biopsy is a common diagnostic test for multiple myeloma.The care team will take a bone marrow sample by using a bone marrow biopsy (typically a core needle biopsy or fine needle aspiration).

After performing the bone marrow aspiration, pathologists examine the cells from a biopsy sample under a microscope to look for the presence of myeloma cells in the bone marrow and note how many are found to help formulate a thorough diagnosis.

Imaging tests

The care team may order imaging studies as part of the multiple myeloma diagnosis process, such as:

  • Computed tomography (CT scan): During this test, the care team will take X-rays from different angles to visualize certain organs and bones.
  • Positron emission tomography (PET-CT scan): During this test, the patient will be administered a type of radioactive sugar, which is then absorbed by cancer cells. The PET-CT scan allows the care team to see which body parts have taken up the sugar to identify potentially cancerous areas.
  • Magnetic resonance imaging (MRI): During this test, the care team makes scans using radio waves and magnets to visualize the patient's bones and bone marrow.

Lab tests

The cancer care team may use blood tests, such as a complete blood count, to check the amount of red blood cells, white blood cells and platelets in the blood, which are often lower than normal from the disease. The care team may also check protein levels in the blood or urine, as well as levels of blood urea nitrogen (BUN), creatinine, albumin and calcium.

Lactic dehydrogenase (LDH) testing: The care team may evaluate the patient's LDH levels during the diagnostic process to help guide the prognosis.

Serum free light chain testing: This blood test allows the care team to measure light chains. This data can help guide how aggressive the disease is.

Urinalysis: An analysis of the patient's urine may help the care team evaluate whether myeloma proteins are present. The patient may be asked to provide urine samples over a 24-hour period in a test known as urine protein electrophoresis (UPEP) and urine immunofixation.

Flow cytometry: A flow cytometry test for multiple myeloma may provide valuable insight into whether the tumor cells contain a normal or abnormal amount of DNA, and the relative rate at which the tumor is growing.

Making a multiple myeloma diagnosis

After performing a variety of tests and examining the patient, the care team will determine whether the patient has multiple myeloma. Diagnosing myeloma typically requires:

  • A plasma cell tumor confirmed via biopsy or a minimum of 10 percent plasma cells were found in the bone marrow, and
  • A least one of these markers:
    • A low red blood cell count (anemia)
    • Inadequate kidney function
    • High levels of blood calcium
    • A least 60 percent plasma cells in the bone marrow
    • Holes in the bones due to tumors
    • Elevated light chain in the blood

Next topic: How is multiple myeloma treated?

Expert cancer care

is one call away.
appointments in as little as 24 hrs.