Multiple myeloma is a blood disorder related to lymphoma and leukemia, because it usually arises in the bone marrow. There is no cure for multiple myeloma, but treatments are available that slow its progression.
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In multiple myeloma, a certain kind of white blood cell called a plasma cell begins to multiply abnormally within the bone marrow. Normally, plasma cells are responsible for producing antibodies that help fight infections. In multiple myeloma, however, excessive plasma cells release unhealthy levels of protein (called immunoglobulin) into the bones and blood. The excessive protein accumulates throughout the body, causing organ damage.
The plasma cells also cause problems inside bones, where they multiply and crowd out normal blood cells. Inside the bone marrow, multiple myeloma plasma cells release chemicals that prompt the body to dissolve areas of bone. This creates weak areas of bone, which are called lytic lesions.
As multiple myeloma progresses, plasma cells begin to spill out of the bone marrow and deposit elsewhere in the body, causing further organ damage.
Causes of Multiple Myeloma
Multiple myeloma's cause is unknown. Certain risk factors slightly increase a person's chances of developing multiple myeloma. The risk factors are:
Being over age 65
Having a family member affected by multiple myeloma
A significant number of people with certain conditions will develop multiple myeloma. These conditions are:
Monoclonal gammopathy of uncertain significance (MGUS)
Rather than being causes of multiple myeloma, these conditions may be early forms of multiple myeloma.
Multiple Myeloma Symptoms
Early on, multiple myeloma may cause no symptoms. As multiple myeloma progresses, plasma cells accumulate in the bones, causing these symptoms:
Bone pain due to lytic bone disease
Weakness and fatigue due to anemia
Confusion, excessive thirst, constipation due to hypercalcemia
Infections due to non-functioning immunoglobulins
Uncommonly, plasma cells may accumulate in purplish lumps visible underneath the skin. These masses are called extramedullary plasmacytomas.
Multiple Myeloma Diagnosis
Most often, testing for multiple myeloma begins after a doctor discovers abnormal blood tests in someone with or without symptoms of multiple myeloma. Some common lab-test clues to the presence of multiple myeloma are:
High protein levels in blood, combined with a low albumin level (a "globulin gap")
Protein in the urine
When a doctor suspects multiple myeloma, tests of the blood, urine, and bones can make the diagnosis. The most important lab tests of the blood and urine are:
Serum protein electrophoresis (SPEP) and immunoelectrophoresis (IFE)
Urine protein electrophoresis (UPEP) and urinary immunoelectrophoresis (UFE)
Ninety-seven percent of people with multiple myeloma have an abnormal result on SPEP, UPEP, or both tests.
An abnormal SPEP (IFE) and/or UPEP (UFE) may lead doctors to recommend a bone marrow biopsy. A bone marrow biopsy is a necessary step in the diagnosis of multiple myeloma. A needle is inserted into a bone, usually in the hip, and a sample of bone marrow is extracted. A diagnosis of multiple myeloma is made when the biopsy reveals an abnormally high number of plasma cells in the bone marrow.
Imaging tests also help doctors make a diagnosis of multiple myeloma and measure its spread. Plain X-ray films of the body's large bones (called a skeletal survey) can identify spots of bone weakened by multiple myeloma. In a few people, a CT scan, MRI, or PET scan may be needed to find bone involvement from multiple myeloma.