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Multiple Myeloma Blood Test: Which Results Suggest It and What Confirms It

No single routine blood test diagnoses multiple myeloma. Anemia, high calcium, high creatinine, high total protein, high globulin, a low A/G ratio or a low anion gap can prompt a closer look, and each has far more common causes. Myeloma is confirmed with serum protein electrophoresis and immunofixation, serum free light chains, urine studies, a bone marrow biopsy and imaging.

Published

November 13, 2026

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14 min read

Medically reviewed by

Rhonda Collins, FNP-C

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No single routine blood test can diagnose or rule out multiple myeloma. Routine labs can only hint at it. The clues are anemia on a complete blood count (CBC), high calcium, high creatinine, high total protein, high globulin, a low albumin to globulin (A/G) ratio, a high ESR or a low anion gap, and each of those has far more common causes than cancer. Myeloma is confirmed with specific protein tests on blood and urine, which look for a monoclonal protein (an M protein or M spike), followed by a bone marrow biopsy and imaging ^[1][2].

The American Cancer Society says there are no recommended screening tests for myeloma in most people, although it is sometimes found early when a routine blood test shows a high amount of protein ^[1]. This page explains which results are worth a second look, which tests confirm or rule out myeloma, and what MGUS and smoldering myeloma mean if a monoclonal protein turns up.

The short answer

• Routine labs raise the question. They do not answer it. A CBC and a comprehensive metabolic panel can show anemia, high calcium, kidney strain or high protein. Each of these has a broad list of possible causes, most of them not cancer ^[18].
• Protein studies find the monoclonal protein. Serum protein electrophoresis (SPEP), immunofixation and a serum free light chain test look for the single antibody that myeloma cells overproduce ^[2].
• A bone marrow biopsy and imaging confirm myeloma. A diagnosis requires at least 10% clonal plasma cells in the bone marrow, or a biopsy-proven plasma cell tumor, plus at least one sign of myeloma-related harm ^[2][4].
• Most monoclonal proteins are not myeloma. About 3% of people 50 and older have MGUS, a monoclonal protein without cancer. It turns into myeloma or a related disorder at about 1% per year ^[12][13].

Which routine blood results can hint at myeloma

Multiple myeloma is a cancer of plasma cells, the white blood cells in the bone marrow that make antibodies. Myeloma cells crowd the marrow, weaken bone and release large amounts of one antibody, or part of one. Those effects are what routine labs pick up ^[17]. StatPearls describes the most common manifestations as high calcium, kidney dysfunction, anemia and bone pain with lytic lesions, and notes that each of these findings has a broad list of possible causes ^[18].

The largest description of how myeloma looks at diagnosis comes from a Mayo Clinic review of 1,027 people newly diagnosed between 1985 and 1998. Their median age was 66. At diagnosis ^[3]:

• 73% had anemia;
• 13% had a calcium of 11 mg/dL or higher;
• 19% had a serum creatinine of 2 mg/dL or higher.

So anemia is common in myeloma, while very high calcium and clear kidney failure are present in a minority. The table below sets each routine clue beside its more common explanations.

Two of these clues are weaker than they look online:

• High total protein and high globulin can be normal in myeloma. In light chain myeloma, the cells make only light chains, which are small and pass into the urine. A study of people with known monoclonal proteins found that in the light chain group, average total protein and globulin stayed within normal limits ^[7]. Light chain myeloma made up 20% of cases in the Mayo review ^[3].
• A low anion gap is not a sensitive clue. In that same study, the gap was low in only 22% of people with an IgG monoclonal protein, and the authors concluded it was not a sensitive tool for suspecting the diagnosis ^[7]. MedlinePlus notes that low albumin is the most common cause of a low anion gap ^[8].

What a high globulin, high total protein or low anion gap result might mean

These three results usually come from the same routine panel, and they lead to the same next question: is there a monoclonal protein?

Globulin is calculated as total protein minus albumin. When it is high, the cause is usually a broad rise in many different antibodies, called a polyclonal pattern. That is what infection, chronic inflammation and autoimmune disease produce ^[6]. A single clone of plasma cells instead makes one antibody in large amounts. On protein electrophoresis, that shows up as one narrow band, the M spike ^[2][6].

So the useful next step for an unexplained high globulin or high total protein is to repeat the result and, if it persists, to have serum protein electrophoresis. The test sorts blood proteins into albumin and alpha-1, alpha-2, beta and gamma globulins, and shows whether a rise is broad or a single band ^[6]. MedlinePlus lists multiple myeloma, MGUS, Waldenström macroglobulinemia, lymphomas, chronic lymphocytic leukemia, chronic inflammatory disease and acute infection among the causes of high gamma globulin ^[6].

For a low anion gap, the order is different. Repeat the electrolytes and check albumin first, because error and low albumin explain most low results ^[8]. Protein electrophoresis becomes relevant when the low gap persists with normal albumin, or comes with other clues from the table above.

Which tests confirm or rule out myeloma

When routine results or symptoms suggest myeloma, the National Cancer Institute and the American Cancer Society describe a standard set of tests ^[2][4]:

The blood tests work as a set because each one misses some cases. In the Mayo review, serum protein electrophoresis showed a band in 82% of people with myeloma, and immunofixation found a monoclonal protein in 93% ^[3]. The free light chain test matters most for the small group in whom electrophoresis finds no M protein, because electrophoresis measures whole antibodies and cannot measure light chains on their own ^[2]. MedlinePlus notes that kidney disease can raise free light chain levels without any plasma cell disorder, so the ratio is read alongside kidney function ^[10].

A normal serum protein electrophoresis result therefore lowers the chance of myeloma but does not rule it out on its own, particularly light chain myeloma.

How myeloma is diagnosed

The International Myeloma Working Group (IMWG) updated the definition of myeloma in 2014 ^[11]. As summarized by the National Cancer Institute and the American Cancer Society, a diagnosis needs either at least 10% clonal plasma cells in the bone marrow or a biopsy-proven plasma cell tumor, plus at least one myeloma-defining event ^[2][4]:

• calcium more than 1 mg/dL above the upper limit of the reference range;
• creatinine above 2 mg/dL, or creatinine clearance below 40 mL/min;
• hemoglobin below 10.0 g/dL;
• one or more bone lesions on X-ray, CT, PET/CT or MRI;
• 60% or more clonal plasma cells in the bone marrow;
• an involved to uninvolved serum free light chain ratio of 100 or more;
• more than one focal lesion of at least 5 mm on MRI.

The first four are often remembered as CRAB: calcium, renal (kidney), anemia and bone ^[11]. These thresholds are for diagnosis by a specialist using the full workup. A calcium or creatinine result that crosses one of these numbers on a routine panel does not mean myeloma, because the finding has to be caused by a plasma cell disorder.

MGUS and smoldering myeloma

Most monoclonal proteins found on blood tests are not myeloma. They belong to one of two earlier, symptom-free conditions.

Monoclonal gammopathy of undetermined significance (MGUS) means a monoclonal protein below 3 g/dL, fewer than 10% clonal plasma cells in the bone marrow, and none of the myeloma-defining events above ^[2][4]. A study that tested the blood of 21,463 residents of Olmsted County, Minnesota, found MGUS in 3.2% of people 50 and older and 5.3% of people 70 and older ^[12]. A long-term follow-up of 1,384 people with MGUS put the risk of progression to myeloma or a related disorder at about 1% per year ^[13]. The National Cancer Institute gives a range of 0.5% to 1.0% per year in population studies, higher in people with risk factors ^[4]. MGUS is not cancer and is usually monitored with repeat blood tests rather than treated ^[16].

Smoldering myeloma sits between MGUS and active myeloma. It means a serum IgG or IgA monoclonal protein of at least 3 g/dL, or urinary monoclonal protein of at least 500 mg in 24 hours, and/or 10% to 60% clonal plasma cells in the bone marrow, with no myeloma-defining event and no amyloidosis ^[4]. In a Mayo Clinic cohort of 276 people with smoldering myeloma, the risk of progression to active myeloma or amyloidosis was 10% per year for the first 5 years, about 3% per year for the next 5, and 1% per year after that ^[14]. Smoldering myeloma is usually monitored closely, and some higher-risk people are offered treatment ^[4].

Nearly all myeloma is preceded by MGUS ^[4]. That is why a monoclonal protein found by chance leads to a follow-up plan rather than a one-time answer.

When to follow up, and with whom

NICE guidance from the UK gives a concrete rule. For people aged 60 and over with persistent bone pain, particularly back pain, or a fracture with no clear cause, it recommends a full blood count, calcium, plasma viscosity or ESR, serum protein electrophoresis and serum free light chains, and a suspected cancer referral if those results suggest myeloma ^[15].

The National Cancer Institute and the American Cancer Society list these symptoms as reasons to see a doctor ^[16][19]:

• bone pain, especially in the back or ribs, or bones that break easily;
• fever with no known cause or frequent infections;
• easy bruising or bleeding;
• feeling very tired or weak, or short of breath;
• symptoms of high calcium, such as thirst, frequent urination, constipation, nausea or confusion.

Sudden severe back pain with numbness or weakness in the legs can mean spinal cord compression, which the American Cancer Society describes as a medical emergency ^[19].

If a routine panel shows a persistent high globulin, high total protein, unexplained anemia, high calcium or rising creatinine, your primary care clinician is the right first stop. They can repeat the result, look for common causes and order protein electrophoresis. A confirmed monoclonal protein, an abnormal free light chain ratio or any myeloma-defining finding is a reason for a hematology referral.

What blood work cannot tell you

• A normal routine panel does not rule out myeloma. About a quarter of people in the Mayo review had no anemia at diagnosis, most had a calcium below 11 mg/dL, and light chain myeloma often leaves total protein and globulin normal ^[3][7].
• An abnormal routine panel does not diagnose it. Anemia, high calcium, high creatinine, high globulin and a high ESR all have common, non-cancerous causes, and ESR alone cannot diagnose which condition is causing inflammation ^[9].
• A monoclonal protein does not mean cancer. Most people with one have MGUS, and most people with MGUS never develop myeloma ^[12][13].
• No blood test alone stages or confirms myeloma. The diagnosis rests on the bone marrow and imaging as well as blood and urine tests ^[2][4]. Beta-2 microglobulin and LDH are used to stage myeloma once it is diagnosed, not to find it ^[2].

Where the SPE blood test fits

Mito’s Total Protein and Protein Electrophoresis (SPE) Blood Test measures total protein and albumin and separates the globulins into alpha-1, alpha-2, beta and gamma fractions. It reports any monoclonal protein band it finds. It is a reasonable follow-up when a routine panel shows a persistent high total protein, high globulin or low A/G ratio and you want to see whether the rise is a broad pattern or a single band.

It is not a cancer screening test and it cannot diagnose myeloma. It does not include immunofixation, a serum free light chain test or urine studies, so a normal result does not rule out light chain myeloma. If it shows a band, the next steps are those tests and a clinician’s review. A CBC and a comprehensive metabolic panel cover the anemia, calcium, creatinine and protein clues in the table above.

Related reading

• Symptoms of high globulin
• Symptoms of high total protein
• A/G ratio: what it means
• Low anion gap: causes and what to do next
• Does lymphoma show up in blood work?
• Is high calcium a sign of cancer?

References

1. American Cancer Society: Can Multiple Myeloma Be Found Early?
2. American Cancer Society: Tests for Multiple Myeloma
3. Kyle RA et al. Review of 1027 patients with newly diagnosed multiple myeloma. Mayo Clin Proc. 2003.
4. National Cancer Institute: Plasma Cell Neoplasms (Including Multiple Myeloma) Treatment (PDQ), Health Professional Version
5. MedlinePlus: Total Protein and Albumin/Globulin (A/G) Ratio
6. MedlinePlus: Protein electrophoresis - serum
7. van Hoeven KH et al. The anion gap and routine serum protein measurements in monoclonal gammopathies. Clin J Am Soc Nephrol. 2011.
8. MedlinePlus: Anion Gap Blood Test
9. MedlinePlus: Erythrocyte Sedimentation Rate (ESR)
10. MedlinePlus: Free Light Chains
11. Rajkumar SV et al. International Myeloma Working Group updated criteria for the diagnosis of multiple myeloma. Lancet Oncol. 2014.
12. Kyle RA et al. Prevalence of monoclonal gammopathy of undetermined significance. N Engl J Med. 2006.
13. Kyle RA et al. A long-term study of prognosis in monoclonal gammopathy of undetermined significance. N Engl J Med. 2002.
14. Kyle RA et al. Clinical course and prognosis of smoldering (asymptomatic) multiple myeloma. N Engl J Med. 2007.
15. NICE: Suspected cancer: recognition and referral (NG12), recommendations organised by site of cancer
16. National Cancer Institute: Plasma Cell Neoplasms (Including Multiple Myeloma) Treatment, Patient Version
17. MedlinePlus: Multiple myeloma
18. Albagoush SA et al. Multiple Myeloma. StatPearls. 2023.
19. American Cancer Society: Signs and Symptoms of Multiple Myeloma

Frequently asked questions

Can a routine blood test detect multiple myeloma?

Not on its own. A complete blood count or metabolic panel can show changes that prompt a closer look, such as anemia, high calcium, high creatinine or high total protein. The American Cancer Society notes that myeloma is sometimes found early this way, but there are no recommended screening tests for it in most people. Confirming it takes protein studies of the blood and urine, a bone marrow biopsy and imaging.

What does a CBC look like with multiple myeloma?

The most common finding is anemia, a low red blood cell count. In a Mayo Clinic review of 1,027 people newly diagnosed with myeloma, 73% had anemia at diagnosis. White cells and platelets can also be low when myeloma crowds the bone marrow. None of these changes is specific to myeloma. Iron deficiency, chronic disease and many other conditions cause anemia far more often.

Can you have multiple myeloma with normal blood work?

Yes. In the same Mayo Clinic review, about a quarter of people had no anemia at diagnosis, most had a calcium below 11 mg/dL and most had a creatinine below 2 mg/dL. In light chain myeloma, total protein and globulin are often normal. Persistent bone pain, especially in the back, or a fracture with no clear cause still deserves a visit when routine labs look fine.

What is the main blood test for multiple myeloma?

Serum protein electrophoresis, usually paired with immunofixation and a serum free light chain test. Electrophoresis looks for a monoclonal protein, also called an M spike. Immunofixation identifies its type, and the free light chain test finds myeloma that makes only light chains. Together these blood tests find a monoclonal protein in most people with myeloma, but a bone marrow biopsy and imaging are still needed to diagnose it.

Does a high globulin level mean myeloma?

Usually not. Globulin rises with infection, chronic inflammation and autoimmune disease far more often than with myeloma. Protein electrophoresis tells the two patterns apart. A broad rise across many antibodies points to inflammation, while one narrow band points to a single clone of plasma cells, which is most often MGUS rather than cancer.

Is a low anion gap a sign of myeloma?

Rarely. A lab error or low albumin explains most low anion gap results. Some myeloma proteins can lower the gap, but in a study of people already known to have a monoclonal protein, the gap was low in only 22% of those with an IgG protein and was not a sensitive clue to the diagnosis.