This article, “Multiple Myeloma Screening: 7 Important Tests Used for Diagnosis,” has been written by Dr. Akram Chang (Cardiovascular Medicine) for educational and informational purposes.
The information provided discusses common blood tests, urine tests, bone marrow examinations, and imaging procedures used in the evaluation and diagnosis of multiple myeloma. It is not intended to replace professional medical advice, diagnosis, or treatment.
Multiple myeloma testing should be recommended and interpreted by qualified healthcare professionals. Abnormal test results do not necessarily confirm cancer, and routine screening is not recommended for most asymptomatic individuals at average risk.
Always consult a qualified physician or hematologist regarding persistent symptoms, abnormal test results, or concerns about multiple myeloma. Never delay or disregard professional medical advice based on information published in this article.
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Most people never need a multiple myeloma screen, and no single test works as one. Doctors look for this blood cancer after symptoms, a physical exam, or an unexpected lab result raises a question. The workup that follows draws on blood tests, urine tests, a bone marrow sample, and imaging. This article explains the seven main groups of tests, what each one can and cannot tell you, and how doctors put the results together.
What Is a Multiple Myeloma Screen?
People use the phrase “multiple myeloma screen” loosely. In practice it usually means the first round of tests ordered when a doctor suspects a plasma cell disorder. Plasma cells are white blood cells in the bone marrow that make antibodies. In myeloma, abnormal plasma cells multiply and often release large amounts of one identical antibody, or a fragment of it. That product is called monoclonal protein, M protein, or paraprotein.
True population screening, meaning testing people who feel fine, is a different matter. The American Cancer Society states that no screening tests are recommended for multiple myeloma in most people. Doctors do watch people at higher risk, such as those with monoclonal gammopathy of undetermined significance (MGUS) or a solitary plasmacytoma, with regular blood work.
Who May Need Multiple Myeloma Testing?
Testing usually begins in one of three ways. A person may have symptoms that don’t resolve. A routine blood or urine test may show something unexpected, such as anemia with no clear cause, high calcium, reduced kidney function, or a high total protein level. Or someone already known to have MGUS may be due for a scheduled check.
Because the findings are nonspecific, myeloma is sometimes found late. Fatigue and back pain have countless explanations, and most people with those complaints do not have cancer. A physician decides which tests fit each situation, so nobody should try to order a full set on their own.
Symptoms That May Lead to Testing
Doctors often remember the CRAB features when thinking about myeloma-related organ damage:
| Letter | Feature | What patients may notice |
|---|---|---|
| C | Elevated calcium | Thirst, frequent urination, constipation, nausea, confusion |
| R | Renal (kidney) impairment | Foamy urine, swelling, changes in urine output, often no symptoms early on |
| A | Anemia | Fatigue, weakness, dizziness, shortness of breath |
| B | Bone lesions | Persistent back, rib, or hip pain; fractures after minor injuries |
Other clues include frequent infections, because abnormal plasma cells crowd out the cells that make working antibodies. Unexplained bruising or bleeding can occur when platelet counts fall.
None of these signs is unique to myeloma. Thyroid problems, vitamin deficiencies, ordinary arthritis, and many other conditions look similar. Pain or fatigue that lasts, worsens, or has no explanation is a good reason to see a clinician.
7 Important Tests Used for Multiple Myeloma Diagnosis
The seven groups below bundle related tests. Few patients need every one, and the order and mix vary with the clinical picture.
1. Complete Blood Count (CBC)
A CBC counts red cells, white cells, and platelets and measures hemoglobin. When myeloma cells take up space in the marrow, production of healthy cells can drop. The usual finding is anemia, sometimes with low white cell or platelet counts. A blood smear under the microscope may show red cells stacked like coins, called rouleaux, which happens when high protein levels make cells cling together.
Anemia on its own proves little. It is far more often caused by iron deficiency, chronic illness, or blood loss than by myeloma.
2. Blood Chemistry and Kidney Function Tests
These panels check calcium, creatinine, blood urea nitrogen, albumin, and electrolytes. Creatinine and urea show how well the kidneys filter waste. Myeloma can injure the kidneys when excess light chains build up in the kidney’s filtering tubes, so these numbers carry real weight.
Beta-2 microglobulin, albumin, and lactate dehydrogenase (LDH) come into play later, because they feed into staging.
These are the routine blood tests for multiple myeloma that often provide the first hint. One caution applies: normal calcium and creatinine do not rule myeloma out, because both tend to rise later in the disease.
3. Serum Protein Electrophoresis (SPEP)
SPEP is the central blood test in a multiple myeloma screen. It sorts serum proteins into bands (albumin, alpha, beta, and gamma globulins) using an electric field. A clone of abnormal plasma cells making a single antibody can produce a sharp, narrow spike, often called an M-spike, in the gamma region.
A spike is a lead, not a diagnosis. MGUS and smoldering myeloma produce one too, and so can some infections and autoimmune conditions.
4. Serum Immunofixation Electrophoresis (IFE)
When SPEP finds a suspicious band, immunofixation identifies it. The lab can tell which heavy chain (IgG, IgA, IgM) and which light chain (kappa or lambda) is involved, so a result might read “IgG kappa.” Some patients make only light chains. Knowing the type helps doctors characterize the disorder and choose tests for later monitoring.
5. Serum Free Light Chain Assay
Antibodies are built from heavy and light chains, and plasma cells release a small surplus of light chains into the blood. This assay measures free kappa and lambda chains and their ratio. A ratio far from normal suggests one clone is overproducing.
The test earns its place when SPEP looks normal. People with light-chain myeloma or very low-secreting disease can be missed by SPEP alone. Kidney impairment can change light-chain levels, so doctors read the ratio alongside kidney function rather than in isolation.
6. Urine Tests for Multiple Myeloma
Light chains are small enough to pass through the kidneys into urine, where they were historically called Bence Jones protein. A doctor may order a urinalysis, a 24-hour urine collection to measure total protein, urine protein electrophoresis (UPEP), and urine immunofixation. Which of these are needed depends on the situation. These tests are especially helpful when light-chain disease or kidney involvement is suspected, and they complement the blood tests instead of replacing them. If you’re curious about the kidney’s role here, how the body makes urine explains the filtering process in plain language.
7. Bone Marrow Examination and Imaging
Bone marrow aspiration and biopsy. Samples, usually taken from the back of the pelvic bone, show how many plasma cells are present and whether they are clonal (all descended from one abnormal cell). Labs may add flow cytometry, immunohistochemistry, and genetic tests such as fluorescence in situ hybridization (FISH) to identify chromosomal changes that influence risk. The procedure is done under local anesthetic. People commonly describe pressure and brief deep discomfort, followed by soreness for a day or two.
Imaging. Scans look for bone damage and for disease outside the marrow:
| Imaging test | What it shows best |
|---|---|
| Whole-body MRI | Marrow involvement and focal lesions |
| Whole-body low-dose CT | Bone destruction (lytic lesions) |
| PET-CT | Metabolically active disease and its spread |
| Skeletal survey (X-rays) | Older standard; now used mainly when other options are unsuitable |
The UK’s National Institute for Health and Care Excellence (NICE) advises considering whole-body MRI first, with low-dose CT as an alternative when MRI is unsuitable or declined, and reserving skeletal survey for when neither can be used. Practice in the US also varies by center and availability. For a clearer sense of how the sequences differ, see this explainer on T1 versus T2 MRI.
Plain X-rays can still show fractures, and a refresher on how bone fractures appear on an X-ray shows why they miss early marrow disease that MRI can catch.
Additional Tests for Complications
Not everyone needs more than the core workup. When symptoms point elsewhere, doctors may add an echocardiogram, ECG, troponin, or NT-proBNP if heart involvement from amyloidosis is possible. A kidney biopsy may be considered when the cause of kidney damage is unclear, and a fat-pad biopsy can help look for amyloid deposits. These are targeted additions, not routine steps for every patient.
How Doctors Confirm Myeloma: SLiM-CRAB Criteria
Because no one result is conclusive, doctors apply criteria from the International Myeloma Working Group (IMWG). Active myeloma generally requires at least 10% clonal plasma cells in the bone marrow (or a biopsy-proven plasmacytoma), plus at least one myeloma-defining event. Those events are the CRAB features above or any of three biomarkers, summarized by SLiM:
- S (sixty percent): 60% or more clonal plasma cells in the marrow.
- Li (light chains): an involved-to-uninvolved free light chain ratio of at least 100, with the involved light chain at least 100 mg/L.
- M (MRI): more than one focal lesion of at least 5 mm on MRI.
The International Myeloma Foundation’s summary of the diagnostic criteria notes that the SLiM markers were added in 2014 to identify active myeloma before organ damage develops, which lets treatment start earlier.
The criteria also separate three conditions that can look alike on a first lab report:
| Condition | In simple terms |
|---|---|
| MGUS | A monoclonal protein is present, but marrow plasma cells are under 10% and no myeloma-defining events exist |
| Smoldering myeloma | A more advanced precursor with higher protein or marrow involvement but no myeloma-defining events |
| Active multiple myeloma | The criteria above are met |
Finding an M-protein therefore does not mean someone has cancer. Many people with MGUS live for years without developing myeloma, though they are monitored in case it changes.
Staging and Risk Assessment
Once myeloma is confirmed, doctors judge how advanced and how aggressive it is. The Revised International Staging System (R-ISS) combines four measures: beta-2 microglobulin, albumin, LDH, and high-risk chromosomal changes found by FISH. Stage I carries more favorable features, stage III less favorable ones, and stage II falls in between. A newer system, R2-ISS, uses four stages.
A stage describes biology and does not predict how any one person will do. Age, general health, genetics, and response to treatment all play a part, so be wary of any source that attaches a fixed survival number to a stage.
Follow-Up Tests After Diagnosis
Testing continues after diagnosis. Doctors repeat blood counts, SPEP with M-protein measurement, immunoglobulin levels, free light chains when appropriate, kidney function, calcium, and urine studies when indicated. They may repeat imaging or marrow biopsies as needed.
The pace is individual and depends on treatment phase, response, and risk. As one reference point, NICE advises that people who have completed treatment and recovered be monitored at least every three months, with adjustments for risk factors such as high-risk FISH or kidney impairment. Nobody should assume a monthly schedule applies to them.
Frequently Asked Questions
Can a routine blood test detect multiple myeloma?
Routine tests can raise suspicion through anemia, high calcium, reduced kidney function, or a high total protein. Confirming it takes specialized tests such as SPEP, immunofixation, and free light chains, followed by marrow examination.
What is the most important test?
No single test is enough. SPEP and the free light chain assay find abnormal proteins, the bone marrow biopsy measures plasma cells, and imaging checks the skeleton. NICE guidance specifically cautions against using SPEP, immunofixation, light-chain assays, or urine tests alone to exclude myeloma.
Can myeloma be diagnosed without a bone marrow biopsy?
In most cases a marrow sample is needed. A biopsy-proven plasmacytoma can sometimes serve as the tissue evidence, and doctors interpret it together with the rest of the results.
Does an abnormal M-protein mean cancer?
Not necessarily. It may reflect MGUS, smoldering myeloma, or active myeloma, and the marrow findings and myeloma-defining events decide which.
Is routine screening recommended for everyone?
No. For people at average risk with no symptoms, no screening is advised. People with MGUS or a solitary plasmacytoma are monitored on a schedule their doctor sets.
How often are tests repeated?
It varies. Frequency depends on diagnosis, treatment stage, disease activity, and personal risk factors, so your hematologist sets the schedule.
Conclusion
A multiple myeloma screen is better understood as a stepwise investigation than a one-time check. The path runs from everyday blood and urine tests to targeted protein studies, a marrow sample, and imaging, with each step adding a piece to the picture. Abnormal results at the early stages are common and often turn out to be something far less serious.
If you have persistent bone pain, unexplained fatigue, or an abnormal lab result you don’t understand, take it to your primary care clinician, who can refer you to a hematologist if needed. Bring your lab reports, because they make every conversation more productive.
References
- American Cancer Society, “Can Multiple Myeloma Be Found Early?” (last revised February 28, 2025).
- International Myeloma Foundation, “Multiple Myeloma Diagnostic Criteria.”
- National Institute for Health and Care Excellence, “Myeloma: diagnosis and management (NG35), Recommendations.”