Multiple myeloma is a type of cancer where plasma cells in bone marrow replicate out of control. Doctors use the acronym CRAB to diagnose myeloma by identifying four symptoms.
The National Cancer Institute estimates that in the United States, slightly over
Multiple myeloma, also sometimes just called myeloma, develops in plasma cells in your bone marrow. Plasma cells are a type of white blood cell that helps your body fight infection.
In multiple myeloma, cancerous plasma cells crowd out healthy blood cells and produce M protein. A buildup of M protein can damage the kidneys.
The hallmark signs and symptoms of multiple myeloma fall under the acronym CRAB, which stands for:
- Calcium elevation
- Renal failure (kidney failure)
- Anemia
- Bone disease
Doctors use the presence of these symptoms to tell the difference between precancerous and cancerous disease and to guide treatment.
In a
- 68% had bone disease
- 57% had anemia
- 29% had kidney failure
- 6% had calcium elevation
While this research is in a small population, these conditions are commonly seen in people with multiple myeloma.
Multiple myeloma activates cells that break down bone called osteoclasts. This can lead to elevated calcium in the blood, also called hypercalcemia.
Elevated calcium may cause symptoms such as:
The accumulation of M protein in the blood can result in kidney damage and kidney failure. Hypercalcemia can also impair kidney function.
The early stages of kidney disease often don’t cause symptoms, but your doctor might see signs of kidney problems in urine and blood tests.
Early symptoms of kidney damage can include:
Anemia is when you have a low blood cell count. Overproduction of abnormal plasma cells can crowd out healthy red blood cells, white blood cells, and platelets, which help your blood clot after an injury.
Low levels of healthy blood cells can lead to:
- weakness
- fatigue
- shortness of breath
- dizziness
- increased infections
- easy bruising and bleeding
Increased activation of osteoclasts causes the bones to break down. It often causes symptoms such as:
- easy fractures
- bone pain
- back problems
- bone weakness
If the spine becomes weak from loss of bone mass, there’s an increased risk of a spinal fracture. A spinal fracture can compress the spinal cord and cause:
- sudden and severe back pain
- numbness, usually in the legs
- muscle weakness, usually in the legs
Proteins produced by cancerous plasma cells can damage the nerves and lead to:
- muscle weakness
- numbness
- a pins and needles sensation
A large amount of M protein can thicken the blood. Reduced blood flow to the brain may cause:
- confusion
- dizziness
- stroke-like symptoms, such as weakness on one side
Doctors use the presence of CRAB symptoms to diagnose myeloma and to guide treatment.
Multiple myeloma evolves from a precancerous condition called monoclonal gammopathy of undetermined significance (MGUS). This condition comes with about a 1% chance of progressing to multiple myeloma per year.
MGUS can also develop into another precancerous condition called smoldering multiple myeloma, which has about a 10% chance of turning into multiple myeloma per year.
Doctors use the CRAB symptoms to estimate how far the disease has progressed and to help decide if multiple myeloma is in its precancerous or cancerous forms.
Doctors can use the CRAB symptoms to tell if you have active multiple myeloma or MGUS.
MGUS needs to be actively monitored with regular blood tests but doesn’t require treatment. Your doctor may recommend taking medications to increase your bone density.
Multiple myeloma is diagnosed if at least one CRAB symptom or
- the clonal bone marrow plasma cells are greater than 60%
- the serum free light chain (FLC) ratio is greater than 100 mg/L (the involved FLC level must also be greater than 100 mg/L)
- more than one focal lesion appears on an MRI scan
Many people with myeloma show abnormalities in lab blood tests before they develop symptoms.
Multiple myeloma requires active treatment if one or more CRAB symptoms develop. Treatment usually consists of medications to destroy cancer cells and treat specific symptoms. People in otherwise good health may also be candidates for bone transplants.
In the United States, the most common initial therapy for people eligible for bone transplants is a combination of the medications:
Initial treatment depends on the extent of the disease but usually begins with induction therapy with the above or similar drugs. At times, a stem cell transplant may be recommended.
A long term, follow-up
The development of certain CRAB symptoms may be associated with a less favorable outlook.
Hypercalcemia and anemia can be serious but are
In a
They found that people with hypercalcemia and bone disease had a significantly worse outlook than people without these symptoms. The development of anemia or kidney failure wasn’t associated with a worsened survival rate.
Researchers concluded that the development of bone disease may be the strongest factor in someone’s outlook since it may suggest the disease is close to an advanced stage.
The most common signs and symptoms of multiple myeloma are abbreviated with the acronym CRAB. The development of these symptoms helps doctors tell if you have a precancerous disease or multiple myeloma.
Active treatment is needed if CRAB symptoms develop. Treatment usually involves taking medications to destroy myeloma cells and to treat the specific symptoms it causes.
Your doctor can help you develop a treatment plan tailored to your needs. They can also help you find clinical trials you may be eligible for.