Multiple myeloma is a blood cancer that forms in a plasma cell, a type of white blood cell. It is considered a rare cancer. Worldwide, an estimated 176,404 people were diagnosed with multiple myeloma in 2020. There were about 12,000 cases in India in 2020.
Multiple myeloma is treatable and survival rates are better, especially if the disease is diagnosed early and treated.
Tests for Diagnosing Multiple Myeloma
Multiple myeloma is often diagnosed based on tests, the patient’s symptoms and the doctor’s physical exam of the patient. A diagnosis of multiple myeloma requires either:
- A plasma cell tumor (proven by biopsy) OR at least 10% plasma cells in the bone marrow AND
- At least one of the following CRAB criteria:
- High blood Calcium level (greater than 0.25 mmol/L)
- Poor Renal function with creatinine greater than 2mg/dL
- Anemia with red blood cell counts lower than 10 g/dL
- Bones Lesions or holes found on imaging studies (CT, MRI, PET scan), often described as punched-out, round, radiolucent lesions.
Apart from this, 3 other factors were added on later now known as the SLiM CRAB diagnostic criteria:
- Sixty percent (60%) or more plasma cells in the bone marrow
- Increase in one type of serum Light chain in the blood so that one type is 100 times more common than the other
- Abnormal MRI with more than one focal lesion, each lesion > 5mm.
The following tests are recommended for any person with suspected MM.
- Complete blood count with differential red, white and platelet cell count. Too many myeloma cells in the bone marrow will cause less production of red blood cells. Thus anemia is a common finding in myeloma.
- BUN, creatinine, and electrolyte levels. Creatinine and BUN give us an insight into whether the kidneys are working normally. Renal insufficiency is a sign of MM.
- Albumin is checked because low level is indicative of MM.
- Calcium levels go high in later stages of MM. Hypercalcemia leads to many of the symptoms seen in MM.
- Immunoglobulin testing is done to see if any of the immunoglobulins are higher or lower than normal.
- Beta-2 microglobulin and lactic dehydrogenase (LDH). Both these tests are done to measure prognosis. High levels of both these proteins mean the disease has advanced.
- Urine testing to look for the M-protein. A urine sample which has been collected over 24 hours is more accurate in finding how much M-protein is present. Such tests are called urine protein electrophoresis (UPEP) and urine immunofixation.
- Serum protein electrophoresis (SPEP) and Immunofixation electrophoresis is done to check for the M protein in the blood serum.
- Serum free light chain assay. This is helpful to understand presence of any light chain proteins to be able to classify the myeloma especially in cases when no heavy chains are visible.
- Bone marrow biopsy and aspirate usually done in the pelvic bone. The tissue obtained is examined under a microscope to detect size, shape, grade and number of plasma cells. This tissues sample can also be sent for FISH and immunohistochemistry.
- Imaging with low dose CT or PET scan to check location and spread of the cancer.
- Plasma cell FISH chromosomal test to find chromosomal changes.
- 2-D ECHO is done to rule out amyloid protein deposition in the heart.
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