Multiple myeloma is a rare blood cancer that develops in the plasma cells, which are white blood cells that help you fight infection by making antibodies. Multiple myeloma starts in the plasma cells inside your bone marrow.
People with multiple myeloma have high levels of certain proteins in their blood and urine. An oncologist (a medical doctor specialized in diagnosing and treating cancer) will test for and diagnose multiple myeloma.
Here are the diagnostic steps you might go through if a healthcare provider suspects you could have multiple myeloma:
Multiple myeloma causes changes in the blood cells that may lead to physical signs and symptoms. When you see your healthcare provider, they will probably ask about your symptoms and when they began.
They may ask about possible multiple myeloma symptoms you may have, including:
- Fatigue
- Weakness
- Shortness of breath
- Bleeding
- Bruising
- Frequent infections
- Bone fractures
- Dizziness
They may also ask about symptoms related to multiple myeloma complications. Thirst, increased urination, and constipation can be signs of hypercalcemia (too much calcium in the blood), a complication of multiple myeloma. Leg swelling and itching are potential signs of kidney damage caused by multiple myeloma.
Your healthcare provider will also probably ask about your medical history.
After reviewing your symptoms and medical history, the provider will likely perform a physical exam, paying special attention to any areas of bleeding or bruising. They may also assess for any bone fractures or breaks since multiple myeloma cancer cells can weaken bones, increasing the risk of bone fractures.
Multiple myeloma affects the health of several types of blood cells. Your blood may show signs of multiple myeloma, like abnormal levels of specific proteins or antibodies.
Blood tests that healthcare providers use to help diagnose multiple myeloma include:
- Complete blood count (CBC): A CBC measures the levels of red blood cells, white blood cells, and platelets in the blood. Most people with multiple myeloma have anemia (low red blood cell levels).
- Blood urea nitrogen (BUN) and creatinine tests: These tests determine how well your kidneys are working, as multiple myeloma often affects the kidneys.
- Albumin test: Albumin is a protein that can be low in people with multiple myeloma.
- Calcium test: People with multiple myeloma usually have high calcium levels because the cancer affects bones.
- Quantitative immunoglobulins: This test measures the levels of antibodies in the blood. People with multiple myeloma may overproduce some antibodies.
- Electrophoresis: This test measures the levels of monoclonal (M) protein, an antibody protein made by myeloma cells. Your M protein levels may reveal whether you have multiple myeloma or a related condition.
Multiple myeloma can damage the kidneys, causing high levels of protein in the urine. To test for signs of kidney damage and multiple myeloma, a healthcare provider may ask you to collect all of your urine over 24 hours. They will then send the 24-hour sample to a lab for testing.
A biopsy involves taking a sample of body tissue and sending it to a lab for testing. For a multiple myeloma diagnosis, your healthcare provider will take a sample of bone marrow.
Bone marrow is the soft, spongy tissue in the center of your bones. It’s where blood cells are made. Multiple myeloma starts in the plasma cells in the bone marrow, and people with multiple myeloma have too many plasma cells.
During a bone marrow biopsy, your healthcare provider will use a hollow needle to take a sample of bone marrow, usually from inside your hip bone. The sample will then be examined under a microscope at the lab to determine if cancer cells are present.
They may also want to test the liquid part of the bone marrow, called aspirate. There are several tests they can run on aspirate to confirm whether it has cancer cells.
Imaging tests provide pictures of the tissues inside your body. These can help your healthcare team determine if you have multiple myeloma and how far it may have spread throughout your body. Imaging studies used to diagnose multiple myeloma may include:
- X-ray: A bone X-ray can help your provider determine if myeloma cells have damaged the bones and how severe the damage is.
- Computed tomography (CT) scan: This test uses multiple X-rays to create images of your body. It can help determine whether your bones are weak or damaged.
- Magnetic resonance imaging (MRI) scan: This test uses radio waves and magnets to create images of the soft tissues in your body. It can help assess the health of your bone marrow.
- Positron emission tomography (PET) scan: A PET scan can help detect cancer cells and determine their location in the body. Radioactive glucose (sugar) is injected into the blood. Since cancer cells absorb large amounts of sugar, they also absorb the radioactive material. A special camera can create images of these cells, showing any cancer cells that absorbed the radioactive material.
When a person is diagnosed with multiple myeloma, their healthcare team conducts additional tests to determine the cancer’s stage. Staging is essential for developing an effective treatment plan and giving an accurate prognosis (disease outlook).
Healthcare providers use the Revised International Staging System (RISS) to stage multiple myeloma. This system is based on the amounts of certain cells and substances in the blood.
Multiple myeloma stages include:
- Stage 1: You have high levels of the protein albumin and low levels of an antibody called serum beta-2 microglobulin in your blood.
- Stage 2: Your blood levels do not meet the criteria for stage 1 or stage 3.
- Stage 3: You have high levels of serum beta-2 microglobulin and high levels of an enzyme called lactate dehydrogenase (LDH) in your blood, along with abnormal chromosomes in the cancer cells.
Besides the stage of cancer, other factors that influence a person’s prognosis with multiple myeloma include their age, kidney function, and overall health.
Other chronic health conditions can cause changes to your plasma cells. These conditions may cause similar symptoms to multiple myeloma, but they are not considered cancerous. A healthcare provider may need to rule these out before diagnosing you with multiple myeloma.
Other plasma cell disorders they may test for include:
- Monoclonal gammopathy of undetermined significance (MGUS): This condition occurs when your plasma cells make too many copies of the same antibody. People with MGUS have high levels of M protein in the blood but normal levels of blood cells and calcium. They also have healthy kidney function. MGUS often causes no symptoms.
- Smoldering multiple myeloma (SMM): This early, inactive form of multiple myeloma causes no symptoms and is usually detected with a blood test. It can progress to active multiple myeloma in some people.
- Solitary plasmacytoma: This single plasma cell tumor usually develops in the bone. It may be diagnosed with imaging tests and a biopsy.
- Light chain amyloidosis: This condition causes abnormal growth in plasma cells. It may damage certain organs, such as the heart and kidneys. It’s often diagnosed with a biopsy.
Multiple myeloma is a rare blood cancer that develops in the plasma cells in your bone marrow. If your healthcare provider suspects you may have multiple myeloma, they’ll likely refer you to an oncologist for testing.
Diagnostic tests for multiple myeloma may include blood, urine, and imaging tests, as well as biopsies. Multiple myeloma may cause high calcium and low red blood cell levels, poor kidney health, and weak bones. Diagnostic tests help detect these and other signs of multiple myeloma.
