Plasma cell myeloma, also called multiple myeloma, is a rare blood cancer that requires careful diagnostic testing to confirm its presence and guide treatment decisions. Early identification through blood, urine, and bone marrow tests can help doctors understand the extent of the disease and develop the most appropriate care plan for each patient.

Introduction: Who Should Undergo Diagnostics

Plasma cell myeloma is a cancer that develops in plasma cells, which are a type of white blood cell found in bone marrow. These cells normally produce antibodies to help the body fight infections. In myeloma, plasma cells become abnormal and multiply uncontrollably, crowding out healthy blood cells and causing various health problems throughout the body.^[1][2]

Many people with plasma cell myeloma may not experience any symptoms in the early stages. The disease is sometimes discovered accidentally when blood or urine tests are performed for another condition, and doctors notice higher than normal levels of protein.^[3] This is why regular medical checkups are important, especially as people age, since most individuals diagnosed with this condition are over 65 years old.^[7]

However, when symptoms do appear, they can vary widely. Bone pain, particularly in the back, chest, ribs, or hips, is often the first symptom that prompts people to seek medical attention.^[2][3] Other signs that should lead someone to consult a doctor include frequent infections, unusual tiredness or weakness, unexplained weight loss, and frequent thirst or urination. Some people notice bruising or bleeding more easily than usual, or they may feel confused or mentally foggy.^[2][3]

Certain individuals have a higher risk of developing plasma cell myeloma and should be particularly attentive to potential symptoms. Men are more likely to develop the disease than women. The condition is more than twice as common among Black people compared to White people.^[3] Age is the most significant risk factor, with people younger than 45 rarely developing the disease.^[3] Additionally, individuals who are overweight or obese have a higher risk, as do those who have been exposed to certain environmental factors such as radiation, pesticides, or specific chemicals.^[3][5]

Diagnostic Methods for Plasma Cell Myeloma

Diagnosing plasma cell myeloma requires a combination of different tests and procedures. No single test can confirm the disease on its own, so doctors use multiple approaches to build a complete picture of what’s happening in the body. The diagnostic process aims to identify abnormal plasma cells, measure the proteins they produce, and assess any damage to bones or organs.^[4][10]

Blood Tests

Blood tests are among the most important tools for diagnosing plasma cell myeloma. When abnormal plasma cells multiply, they produce unusual proteins called M proteins (also called monoclonal proteins). These proteins can show up in blood samples and serve as a key indicator of the disease.^[8][10]

Healthcare providers look for M proteins through specialized blood tests. Another protein that myeloma cells produce, called beta-2-microglobulin, can also be detected in the blood and helps doctors understand how advanced the disease might be.^[10] When M proteins are present in significant amounts, they can cause the blood to become thicker than normal, which can lead to circulation problems.^[8]

Additional blood tests provide important clues about how myeloma is affecting the body. Doctors check blood cell counts to see if the abnormal plasma cells are crowding out healthy red blood cells, which would cause anemia—a condition marked by low red blood cell counts that leads to tiredness and weakness.^[5] They also measure calcium levels, since myeloma can cause bones to release too much calcium into the bloodstream. Kidney function tests are crucial because the abnormal proteins produced by myeloma cells can damage the kidneys.^[10]

Urine Tests

Urine testing is another essential diagnostic tool. M proteins can appear in urine samples, where they’re called Bence Jones proteins.^[10] The presence of these proteins in urine is significant because they can harm the kidneys over time. Doctors typically collect urine over a 24-hour period to get an accurate measurement of how much of these proteins the body is producing.^[4]

Bone Marrow Tests

Examining the bone marrow is critical for confirming a diagnosis of plasma cell myeloma. The bone marrow is the soft, spongy tissue inside bones where blood cells are made. Doctors perform two related procedures to obtain bone marrow samples: bone marrow biopsy and bone marrow aspiration.^[10]

In a bone marrow biopsy, a needle is used to remove a small amount of the solid bone marrow tissue. In bone marrow aspiration, a needle draws out a sample of the liquid portion of the bone marrow. These samples are usually taken from the hip bone. The procedures might sound uncomfortable, but doctors use local anesthesia to minimize discomfort.^[10]

Once collected, the bone marrow samples are sent to a laboratory where specialists examine them under a microscope to look for myeloma cells. They count how many abnormal plasma cells are present and study their characteristics. In plasma cell myeloma, more than 10 percent of the bone marrow may be made up of abnormal plasma cells.^[8][11]

Advanced laboratory techniques can also identify specific genetic changes in the myeloma cells. A test called fluorescence in situ hybridization (FISH) looks for changes in the cells’ DNA. These genetic details help doctors understand how aggressive the myeloma is and how it might respond to different treatments.^[10]

Imaging Tests

Imaging tests help doctors see whether myeloma has damaged bones or formed tumors. Several types of imaging may be used depending on what doctors need to see. A skeletal survey uses X-rays to examine bones throughout the body, looking for areas where myeloma has caused damage or weak spots.^[10]

Magnetic resonance imaging (MRI) creates detailed pictures of bones and soft tissues using magnets and radio waves. This test is particularly useful for examining the spine and identifying areas where myeloma might be pressing on nerves or the spinal cord.^[10]

Computed tomography (CT) scans use X-rays and computers to create cross-sectional images of the body. These scans can show bone damage more clearly than regular X-rays and help doctors see if myeloma has spread to different areas.^[10]

Positron emission tomography (PET) scans use a small amount of radioactive material to highlight areas where cells are very active, which can indicate the presence of cancer cells. PET scans are sometimes combined with CT scans to provide even more detailed information.^[10]

Diagnostic Criteria

To formally diagnose plasma cell myeloma, doctors look for specific findings. The diagnosis requires evidence of abnormal plasma cells in the bone marrow, the presence of M proteins in blood or urine, or characteristic damage to bones shown on imaging tests.^[4][8] Not every patient will have all these findings, but a combination of them confirms the diagnosis.

Sometimes doctors identify a related condition called monoclonal gammopathy of undetermined significance (MGUS). In MGUS, M proteins are present in the blood, but there are fewer abnormal plasma cells in the bone marrow (less than 10 percent), and there’s no evidence of organ damage. MGUS is not cancer, but it has about a 1 percent chance per year of progressing to myeloma, so people with MGUS need regular monitoring.^[7][8]

Another condition in the spectrum is smoldering multiple myeloma (SMM), which is an intermediate stage between MGUS and active myeloma. People with SMM have higher levels of M proteins and more abnormal plasma cells than those with MGUS, but they don’t yet have symptoms or organ damage.^[4]

When myeloma cells form a single tumor in bone, it’s called a plasmacytoma. If there’s only one tumor and less than 10 percent of the bone marrow consists of plasma cells, this is termed isolated plasmacytoma of bone. When plasma cell tumors develop outside the bones, in soft tissues like the throat or sinuses, they’re called extramedullary plasmacytomas.^[8][11]

Staging the Disease

After diagnosis, doctors determine the stage of the myeloma, which describes how far the disease has progressed. Staging helps guide treatment decisions. The stages range from 1 to 3, with stage 1 being the earliest and stage 3 the most advanced.^[10]

Staging takes into account factors like the levels of certain proteins in the blood, the amount of albumin (a protein that indicates overall health), beta-2-microglobulin levels, and specific genetic changes in the myeloma cells. All these pieces of information together help doctors predict how the disease might behave and what treatments are most likely to be effective.^[4]

Diagnostics for Clinical Trial Qualification

Clinical trials are research studies that test new treatments for plasma cell myeloma. To participate in a clinical trial, patients must meet specific requirements, and diagnostic tests play a crucial role in determining eligibility. These tests ensure that the trial is appropriate for the patient and that researchers can accurately measure how well the treatment works.

For clinical trial enrollment, doctors typically require a complete set of baseline tests. These include comprehensive blood tests to measure M protein levels, beta-2-microglobulin, blood cell counts, kidney function, and calcium levels. Urine tests to detect Bence Jones proteins are also standard.^[4][10]

Bone marrow examination is almost always required for clinical trials. Researchers need to know exactly how many myeloma cells are present in the bone marrow and what genetic characteristics they have. The FISH test to identify specific genetic changes is particularly important because some clinical trials focus on myelomas with particular genetic features.^[10]

Imaging studies form another key part of clinical trial qualification. A skeletal survey, MRI, CT scan, or PET scan may be needed to document the extent of bone disease at the start of the trial. This allows researchers to track whether the treatment is reducing or stabilizing bone damage over time.^[10]

Clinical trials may have additional specific requirements. Some trials only accept patients at certain stages of the disease—for example, only those with newly diagnosed myeloma or only those whose disease has returned after previous treatment. Others may require that patients have specific genetic markers or protein levels. The patient’s overall health status, including heart and lung function, may also be assessed to ensure they can safely receive the experimental treatment.^[4]

Throughout a clinical trial, patients undergo regular monitoring with the same diagnostic tests used at enrollment. This repeated testing allows researchers to measure how the disease is responding to treatment. Blood and urine tests may be performed monthly or even more frequently to track M protein levels. Bone marrow biopsies might be repeated at specific intervals to see if the number of myeloma cells is decreasing. Follow-up imaging shows whether bone lesions are healing or new ones are developing.^[4]

All these diagnostic procedures help researchers and doctors work together to determine whether experimental treatments are safe and effective. For patients, participating in a clinical trial means receiving very close medical monitoring, which can be beneficial even beyond the potential access to new therapies.