Multiple myeloma is diagnosed based on the results of clinical tests. Test findings such as cancer cells in the bone marrow, kidney dysfunction, abnormal proteins in the blood, low levels of red blood cells, and imaging scans that show tumors are evidence that doctors use to diagnose myeloma and related disorders.

When multiple myeloma is diagnosed, it is assigned a stage. Read more about multiple myeloma staging.

Diagnostic Criteria for Multiple Myeloma

According to the Revised International Myeloma Working Group, diagnostic criteria for multiple myeloma include one of these major signs, confirmed by a bone marrow biopsy:

• Plasmacytoma (bone lesion)
• Extramedullary (soft tissue) plasmacytoma
• 10 percent or more plasma B cells in the bone marrow are abnormal

A multiple myeloma diagnosis will also likely include evidence of organ damage caused by abnormal plasma B cells, such as:

• Hypercalcemia (high calcium levels in blood)
• Kidney dysfunction
• Anemia (low red blood cell count)
• Bone lesions visible on X-rays

Apart from evidence of organ damage, other signs supporting a diagnosis of multiple myeloma include:

• 60 percent or more plasma B cells in the bone marrow are abnormal
• Abnormal presence of light chains (proteins produced by abnormal plasma B cells)
• More than one lesion visible in magnetic resonance imaging (MRI) studies

Tests and What They Show

About 50 percent of the time, multiple myeloma is diagnosed by primary care physicians. Some people go to their doctors when they experience symptoms such as back pain, bone pain, infections, or fatigue. In approximately 30 percent of cases, multiple myeloma is diagnosed after blood tests for an unrelated condition reveal abnormalities. If your doctor suspects multiple myeloma, they will perform a number of tests to confirm the diagnosis and determine the extent of the cancer.

Once multiple myeloma is suspected, testing can usually be completed within a few weeks. Diagnosis is delayed by six months or more in 50 percent of cases if the diagnosing doctor is a primary care physician.

Medical History and Physical Examination

Your doctor will ask detailed questions about your medical history, including any symptoms such as fatigue, bone pain, and frequent infections. They may ask whether anyone in your family has ever been diagnosed with myeloma or another type of blood cell disorder. The doctor may ask about your work or hobbies to find out whether you may have been exposed to chemicals or radiation that could be one of the risk factors for multiple myeloma. A physical exam will allow your doctor to check for signs such as weight loss, loss of height, neuropathy (pain, numbness, or tingling in the extremities), edema (swelling), or any unusual rashes or skin changes.

Blood and Urine Tests

Results from blood and urine tests are not diagnostic for multiple myeloma, but they can provide evidence that points to multiple myeloma or another condition.

• Calcium levels are abnormally high when bones are being damaged by tumors.
• Anemia, or low red blood cell count, appears when cancer cells are destroying bone marrow.
• Levels of creatinine and urea nitrogen are higher when kidneys are not working well.
• Albumin, a common protein in the blood, is low in some people with myeloma.
• Beta macroglobulin is a protein produced by abnormal plasma B cells.

Urine tests can show levels of light chain proteins (also called M proteins or Bence-Jones proteins) secreted by abnormal plasma B cells.

Bone Marrow Aspiration and Biopsy

If blood and urine test results show strong indicators of multiple myeloma, your doctor will likely order a bone marrow aspiration procedure and biopsy to confirm the diagnosis. These two procedures are often performed at the same time. Bone marrow aspiration is the collection of liquid from bone marrow, while a bone marrow biopsy takes a sample of solid bone marrow. Both the aspiration and biopsy are performed by pushing a needle into a bone, usually the rear portion of the pelvis (hip bone). The doctor will numb the area before performing the aspiration and biopsy to reduce discomfort.

Biopsied bone marrow tissue will be analyzed in a laboratory to assess the ratio of abnormal plasma B cells present in the bone marrow. Cytogenic studies will examine the genes of the cancer cells for traits connected with risk for progression.

Imaging Tests

Imaging tests are used to determine whether there are lesions (tumors) in the bones or soft tissues. X-rays, magnetic resonance imaging (MRI), computed tomography (CT), and positron emission tomography (PET) may be performed to help determine the extent of multiple myeloma. Imaging tests are painless, although PET scans involve an injection.

People suspected of having myeloma or a related disorder are often referred to an oncologist (cancer specialist), hematologist (specialist in blood disorders), or a doctor with combined specialties — a hematologist-oncologist. Another specialist called a hematopathologist examines blood and bone marrow samples in a laboratory to provide details necessary to diagnose and stage myeloma.

Condition Guide

• Multiple Myeloma — An Overview
• Symptoms of Multiple Myeloma
• Myeloma Types and Related Conditions
• Stages of Multiple Myeloma
• Treatments for Myeloma
• What Causes Multiple Myeloma?