Multiple myeloma is a cancer of plasma cells, a type of white blood cell that lives in your bone marrow and normally helps fight infection. In this article you’ll learn what multiple myeloma is, what causes it and who is most at risk, how doctors find and stage it, and how treatment works today. We also explain the blood and urine tests behind a diagnosis, the warning signs worth knowing, and what the outlook looks like now that treatments have improved. The goal is clear, plain-language information so you can read your own results with more confidence and ask better questions at your next appointment.
What is multiple myeloma?
Multiple myeloma is a blood cancer that starts in plasma cells. Healthy plasma cells make antibodies, the proteins that recognize and attack germs. In myeloma, one abnormal plasma cell copies itself again and again until these cancerous cells build up in the bone marrow and crowd out the normal cells that make red cells, white cells, and platelets.
Instead of useful antibodies, the myeloma cells pump out large amounts of a single, identical antibody protein. Doctors call it a monoclonal protein, or M protein. This abnormal protein is the fingerprint of the disease: it shows up in the blood and often in the urine, and it is what most myeloma tests are designed to find. You can see it as a spike on a protein electrophoresis test, usually within the gamma globulin band.
The word “multiple” refers to the fact that the disease usually affects bone marrow in several places at once, often in the spine, pelvis, ribs, and skull. Myeloma is sometimes confused with bone cancer because it damages bone, but it is a cancer of blood cells, not of the bone itself.
The disease spectrum: MGUS, smoldering, and active myeloma
Multiple myeloma rarely appears out of nowhere. According to the National Cancer Institute, it almost always develops from an earlier, silent condition called monoclonal gammopathy of undetermined significance (MGUS). In MGUS, a small amount of M protein is present, but there are no symptoms and no organ damage.
Most people with MGUS never go on to develop cancer. Mayo Clinic notes that only about 1 in 100 people with MGUS each year progresses to myeloma or a related condition. Between MGUS and active disease sits a middle stage called smoldering multiple myeloma, where more abnormal protein is present but the disease still is not causing harm.
Understanding this spectrum matters because it explains why some people are simply monitored for years rather than treated right away. The amount of M protein, the proportion of plasma cells in the marrow, and whether any organ damage has appeared are what separate a condition that needs watching from one that needs treatment.
What causes multiple myeloma, and who is at risk?
The honest answer is that no one knows exactly what causes multiple myeloma. What researchers do know is that the disease begins when genetic changes (mutations) accumulate inside a plasma cell, switching off the normal controls that tell the cell when to stop dividing. Why those changes happen in one person and not another is still being studied.
While the cause is unclear, several factors are linked to a higher chance of developing the disease. Mayo Clinic and the National Cancer Institute describe the most consistent risk factors:
- Age. Most people are diagnosed after 60, and the risk keeps rising with age.
- Sex. Men are somewhat more likely than women to develop myeloma.
- Race. Myeloma is roughly twice as common in Black people as in White people, and it tends to appear at a younger age.
- A history of MGUS. Having MGUS is the single strongest known risk factor.
- Family history. Having a close relative with myeloma slightly raises your own risk, though most cases are not inherited.
- Obesity, and possibly long-term exposure to certain industrial chemicals or high-dose radiation.
It helps to be clear about what does not cause myeloma. It is not contagious, you cannot catch it from another person, and there is no diet or lifestyle choice known to cause it directly. Having one or more risk factors does not mean you will get the disease, and many people who develop myeloma have no obvious risk factors at all.
Symptoms and the CRAB criteria
Early multiple myeloma often causes no symptoms and is picked up by chance on a routine blood test. When symptoms do appear, they come from two things: the myeloma cells damaging bone and marrow, and the abnormal protein affecting the blood and kidneys.
Doctors group the four classic forms of organ damage under the memory aid CRAB. These features are also used to decide whether the disease is active and needs treatment.
| CRAB feature | What it means | What you might notice |
|---|---|---|
| C — Calcium (high) | Bone breakdown releases calcium into the blood (hypercalcemia) | Excessive thirst, frequent urination, constipation, confusion, nausea |
| R — Renal (kidney) | The abnormal protein and high calcium strain the kidneys | Foamy urine, swelling, tiredness, reduced urine output |
| A — Anemia | Myeloma crowds out cells that make red blood cells | Fatigue, weakness, paleness, shortness of breath |
| B — Bone | Myeloma creates weak spots and thinning in the bone | Persistent bone pain (often back or ribs), fractures from minor injury |
Beyond CRAB, multiple myeloma can cause repeated infections, because the body cannot make enough working antibodies, as well as unexplained weight loss, frequent fevers, and numbness or tingling in the hands and feet. Some people first notice that a complete blood count shows anemia, that their calcium level is high, or that their kidney marker creatinine has crept up, all before any other clue appears.
How is multiple myeloma diagnosed?
Diagnosis usually begins not with a dramatic symptom but with a surprising blood result. As Mayo Clinic hematologists describe, myeloma is often suspected when routine tests show an unusually high total protein, a low blood count, or an abnormal kidney number. From there, doctors use a focused set of tests to confirm the disease, measure how much protein is being made, and check for organ damage.
| Test | What it looks for |
|---|---|
| Serum protein electrophoresis (SPEP) | The M protein “spike” in the blood |
| Immunofixation | Confirms the exact type of abnormal antibody |
| Serum free light chains and kappa/lambda ratio | Pieces of antibody made in excess, useful for early detection and monitoring |
| Immunoglobulin levels (IgG, IgA) | Identifies which antibody type is overproduced |
| Total protein and complete blood count | Raised protein and anemia |
| Calcium and creatinine | Hypercalcemia and kidney function |
| 24-hour urine test | Protein in the urine, including light chains known as Bence Jones protein |
| Bone marrow biopsy | The percentage of abnormal plasma cells in the marrow |
| Imaging (low-dose whole-body CT, MRI, or PET) | Bone damage and tumors |
To make a formal diagnosis, doctors look for a high proportion of clonal plasma cells in the bone marrow, generally at least 10 percent, together with at least one sign that the disease is doing harm. That harm can be any CRAB feature, or one of several “myeloma-defining” markers, such as a very high level of plasma cells, a very lopsided free light chain ratio, or more than one focal lesion seen on MRI. When the protein is present but none of these signs are, the diagnosis is MGUS or smoldering myeloma instead, and the plan is usually careful monitoring rather than treatment.
Stages of multiple myeloma
Once myeloma is confirmed, staging helps describe how advanced it is and guides the treatment plan. The most widely used system today is the Revised International Staging System (R-ISS), which combines several routine measurements.
- Beta-2 microglobulin, a protein that rises with the amount of myeloma in the body. A related marker, beta-2 globulins, is reported on standard protein testing.
- Albumin, a protein that tends to fall as the disease becomes more active.
- Lactate dehydrogenase (LDH), an enzyme that can reflect how fast cells are turning over.
- Cytogenetics, meaning specific chromosome changes inside the myeloma cells found on the bone marrow sample.
Stage 1 describes lower-risk disease with favorable markers, while stage 3 describes higher-risk disease. Staging is not a prediction for any single person; it is one tool among several, and your care team weighs it alongside your age, kidney function, and overall health.
Treatment options for multiple myeloma
There is currently no cure for multiple myeloma, but it is very treatable, and treatment has changed dramatically over the past two decades. The aim is to control the disease, relieve symptoms, protect the bones and kidneys, and keep you well for as long as possible. According to the National Cancer Institute, treatment depends heavily on the stage and on whether the disease is causing symptoms.
For MGUS and most smoldering myeloma, the standard approach is watchful waiting, with regular blood tests and check-ups but no drug treatment. Treating these early states too soon has not been shown to help people live longer outside of clinical trials.
When active myeloma needs treatment, doctors usually combine drugs from different families, because attacking the cancer in several ways at once works better than any single drug.
| Treatment type | How it works | Examples |
|---|---|---|
| Proteasome inhibitors | Block the cell’s protein recycling so myeloma cells die | Bortezomib, carfilzomib |
| Immunomodulators | Boost the immune attack and slow cancer growth | Lenalidomide, pomalidomide |
| Monoclonal antibodies | Lab-made antibodies that target a marker (CD38) on myeloma cells | Daratumumab, isatuximab |
| Corticosteroids | Reduce inflammation and help kill myeloma cells | Dexamethasone |
| Stem cell transplant | High-dose chemotherapy followed by a rescue with your own stem cells | Autologous transplant |
Many people who are fit enough have an autologous stem cell transplant after their first round of drug treatment, often followed by lower-dose maintenance therapy to keep the disease in check. When myeloma comes back or stops responding, newer options can help, including CAR T-cell therapy (immune cells engineered in a lab to hunt myeloma) and bispecific antibodies (drugs that link the patient’s own immune cells to the cancer). Supportive care is just as important: bone-strengthening medicines, treatment of anemia and infections, and steps to protect the kidneys all help people feel better and stay active. Your doctor chooses the combination based on your disease, your other health conditions, and your preferences.
Living with multiple myeloma and the outlook
Multiple myeloma is usually a long-term condition that is managed over years, with periods of treatment, periods of remission, and regular monitoring in between. Remission means the disease is under control and the abnormal protein has dropped, not that the cancer is gone for good, so your team keeps tracking your M protein and free light chains to catch any change early.
Survival has improved substantially. Figures from the National Cancer Institute’s SEER program show that, in the United States, roughly 6 in 10 people are alive five years after diagnosis, and outcomes continue to improve as newer treatments arrive. These numbers are averages based on people diagnosed years ago, and they vary widely with stage, genetics, age, and how the disease responds, so they cannot predict any one person’s path. Many people live well for a long time, working, traveling, and staying active between treatments.
When to see a doctor
Most of the symptoms linked to myeloma have far more common, harmless explanations. Still, it is worth talking to a doctor if you notice any of the following, especially if more than one occurs together or symptoms persist:
- Bone pain that lasts for weeks, particularly in the back or ribs, or a bone that breaks after a minor knock
- Unusual, lasting tiredness or breathlessness that could point to anemia
- Frequent or hard-to-shake infections
- Symptoms of high calcium, such as intense thirst, constipation, confusion, or frequent urination
- Foamy urine, swelling, or other signs of kidney trouble
- An abnormal blood result, such as a high total protein or a raised calcium, that your doctor wants to investigate
Seeking advice does not mean you have cancer. It simply allows a doctor to order the right tests and rule things out, which is exactly what early, accurate diagnosis depends on.
Glossary
| Term | Definition |
|---|---|
| Bence Jones protein | Free antibody fragments (light chains) that pass into the urine in many people with myeloma. |
| Bone marrow biopsy | A test that removes a small marrow sample to measure the percentage of abnormal plasma cells. |
| CRAB criteria | The four signs of myeloma-related organ damage: high Calcium, Renal (kidney) problems, Anemia, and Bone damage. |
| Free light chains | Small pieces of antibody measured in the blood; the kappa/lambda ratio helps detect and monitor myeloma. |
| M protein (monoclonal protein) | The single abnormal antibody made by myeloma cells, used to diagnose and track the disease. |
| MGUS | Monoclonal gammopathy of undetermined significance; a silent precursor with a small amount of M protein and no symptoms. |
| Plasma cell | A white blood cell that normally makes antibodies and becomes cancerous in myeloma. |
| Proteasome inhibitor | A class of myeloma drug that blocks the cell’s protein-recycling system. |
| Smoldering myeloma | An in-between stage with more abnormal protein than MGUS but still no organ damage. |
| Stem cell transplant | High-dose chemotherapy followed by a rescue with the patient’s own stored blood stem cells. |
Frequently asked questions
Is multiple myeloma hereditary or does it run in families?
Multiple myeloma is not usually inherited, and most people who develop it have no family history. That said, having a close relative with myeloma or MGUS does slightly raise your own risk, which suggests some genetic influence. The changes that drive myeloma happen inside plasma cells during a person’s lifetime; they are not passed down like eye color. If several close relatives have had myeloma or related blood cancers, mention it to your doctor so your own results can be interpreted with that context in mind.
Can multiple myeloma be cured, and what does remission mean?
At present there is no cure for multiple myeloma, but it is highly treatable, and many people live well with it for many years. Treatment aims for remission, which means the disease is brought under control and the abnormal protein falls, sometimes to undetectable levels. Remission is not the same as being cured, because the disease can return, which is why monitoring continues even when you feel well. Because treatments keep improving, today’s outlook is better than the older statistics suggest.
What is usually the first sign of multiple myeloma?
There is often no obvious first sign, and the disease is frequently found by chance on a blood test done for another reason. When an early symptom does appear, it is most often persistent bone pain, especially in the back or ribs, or unexplained fatigue caused by anemia. Repeated infections and a raised calcium or protein level on routine bloods are other common first clues. None of these point to myeloma on their own, since each has many more common causes, but a combination is worth investigating.
Is multiple myeloma the same as bone cancer?
No. Although myeloma frequently damages bone and causes bone pain, it is a cancer of plasma cells in the bone marrow, not a cancer that starts in the bone itself. True bone cancers, such as osteosarcoma, begin in the bone tissue. The confusion is understandable because weakened bones and fractures are common in myeloma, but the disease and its treatment are quite different from those of primary bone cancer.
Can multiple myeloma show up on a routine blood test?
Often, yes, at least as a clue. Routine tests may reveal anemia, a high total protein, a raised calcium, or an abnormal kidney result, any of which can prompt a doctor to look further. Confirming the diagnosis, however, requires specific tests such as protein electrophoresis, free light chain measurement, a bone marrow biopsy, and imaging. So a routine panel can raise a flag, but it cannot diagnose myeloma by itself.
Is multiple myeloma always terminal?
Multiple myeloma is a serious cancer, but calling it “terminal” is misleading for many people today. It is usually treated as a long-term, manageable condition, with treatment controlling the disease through repeated cycles of remission and follow-up. Survival has improved considerably and continues to do so, and a person’s outlook depends on the stage, the genetics of the disease, age, and how it responds to treatment. Your hematologist can give you the most realistic picture for your individual situation.
Sources
- National Cancer Institute — Plasma Cell Neoplasms (Including Multiple Myeloma) Treatment (PDQ), Patient Version
- Mayo Clinic — Multiple myeloma: Symptoms and causes
- Cleveland Clinic — Multiple Myeloma: Symptoms, Causes and Treatment
Further reading
- How to read your blood test results: a simple guide
- Abnormal blood test results: what they mean
- Tumor markers: meaning, uses, and limits
- Immunoglobulin A (IgA): understanding your blood test
- Lymphoma: symptoms, causes, and treatments
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