Myeloma is a type of cancer affecting a certain type of white blood cell called B-cells or B-lymphocytes. Activated B-cells, also referred to as plasma cells can become cancerous and cause myeloma.
The signs and symptoms of myeloma can be diverse and may not be obvious, especially in the early stages of the disease.
Diagnosing myeloma involves reviewing a patient’s symptoms as well as the results of a physical examination, and tests ordered by the medical practitioner. These can include blood tests, urine tests, bone marrow tests, and different kinds of imaging tests, like X-rays, magnetic resonance imaging (MRI) scans, CT scans, and PET scans.
Among the blood tests that might be given to diagnose myeloma are:
- Complete blood cell (CBC) counts, which measure the total numbers of red blood cells, white blood cells, and platelets in the blood.
- Measures of the levels of M protein, a monoclonal antibody produced by myeloma cells, using techniques such as serum protein electrophoresis (SPEP) or immunoelectrophoresis.
- Measures of the levels of beta-2 microglobulin, a protein produced in excess by cancerous cells.
- Chemistry tests to detect levels of blood urea nitrogen (BUN), creatinine, albumin, calcium, and electrolytes such as potassium and sodium.
Tests here include urine protein electrophoresis (UPEP) and urine immunofixation to detect the levels of Bence Jones proteins in urine, which are shorter pieces of the M protein that are excreted in the urine.
Bone marrow biopsy
A bone marrow biopsy is an invasive procedure that involves getting a small sample of bone and marrow. The sample is analyzed using various tests such as immunohistochemistry, flow cytometry, karyotyping, fluorescent in situ hybridization (FISH), and gene expression profiling or gene array.
These analyses can confirm the presence of cancer cells, chromosomal abnormalities, and changes in gene expression.
Various imaging tests can also be used to help reach a diagnosis of myeloma. These include:
- X-rays, where a single-dimensional image of the bones is taken to look for damage that may be caused by myeloma cells
- Computerized tomography (CT) scan, which produces detailed cross-sectional images of the patient’s body and can help identify damaged bones
- Magnetic resonance imaging (MRI), which uses radio waves to produce cross-sectional slices of the body
- Positron emission tomography (PET) scans use radioactive glucose (sugar) to identify tumors on a scanner. Generally, cancer cells use sugar at a higher rate than normal cells, so that the radioactivity concentrates within the tumor and can be identified by the scanner.
The criteria for a positive myeloma diagnosis include:
- Anemia (low red blood cell counts), defined as hemoglobin levels below 10 g per dL.
- M protein levels of more than 3 g per dL in the blood, or of more than 1 g per dL in the urine.
- Creatinine levels in the blood of more than 2 mg per dL, which indicate kidney problems that may be caused by myeloma.
- High levels of BUN and calcium, and low levels of blood albumin, as well as aberrant blood electrolyte (potassium and sodium) levels.
- Bone marrow biopsy results that prove a plasma cell tumor based on at least 10% or more of the plasma cells.
- Bone lesions or holes as seen on X-rays, and CT or PET scans.
- One or more focal lesions on MRI scans that are greater than 5 mm in size.
Last updated: Feb. 28, 2019
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