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Multiple myeloma is a blood cancer that occurs when healthy plasma cells become abnormal, leading to the production of abnormal antibodies. This change can result in a range of medical problems that affect the bones, kidneys, blood, and the immune system.


Medical Problems Related to Myeloma

  • Anemia: Multiple myeloma and anemia are linked. Anemia occurs when you have low levels of red blood cells. Because multiple myeloma occurs in the bone marrow, it leaves little room for the growth of healthy red blood cells.
  • Bone fractures: Myeloma patients may experience painful vertebral compression fractures. These fractures happen when myeloma affects the bones of the spine ( the vertebrae). The spinal cord runs through the vertebrae. (See the IMF publication Understanding Treatment of Myeloma-Induced Vertebral Compression Fractures)
  • Spinal cord nerve damage: Myeloma tumors (plasmacytomas) may grow in the vertebrae. These tumors can press on spinal nerves. If this occurs, compression of motor nerves may cause paralysis.
  • Bacterial infections: Multiple myeloma impairs the immune response, sometimes resulting in severe infections. (See the IMF publication Understanding the Immune System in Myeloma.)
  • Hypercalcemia: Hypercalcemia is a high level of calcium in the blood. Myeloma and hypercalcemia are linked as patients may experience this condition when bones break down and release calcium. 
  • Kidney problems and failure: Both hypercalcemia and high levels of monoclonal protein in the blood can affect the kidneys. As a result, myeloma patients may have kidney problems or failure.

The following are examples of emergency medical problems that may arise in myeloma patients:

  • Vertebral compression fractures
  • Damage to the nerves of the spinal cord
  • Infections
  • Kidney failure 
  • A high level of calcium in the blood  


Physical Symptoms of Multiple Myeloma

Multiple myeloma can cause various symptoms, including:

  • Bone pain: This is often the first symptom patients experience. 
  • Weakness and numbness in extremities: This may occur when the disease impacts the spinal bones, pressing against your spinal cord. 
  • Fatigue: Extreme fatigue is a common symptom associated with anemia. 
  • Nausea and vomiting: These symptoms could indicate hypercalcemia. 
  • Decreased appetite: This may also be a sign of hypercalcemia. 
  • Fever: This symptom could be related to a bacterial infection. 


Complications in the Bone Marrow

Bone marrow produces white and red blood cells and platelets. When myeloma cells fill the bone marrow, the production of these blood cells is compromised, leading to anemia, a common symptom of multiple myeloma that is often noticeable in the early stages of the disease.

Bone marrow cells play a crucial role in maintaining bone health by breaking down old bone and stimulating new bone growth. However, the presence of multiple myeloma cells interferes with these processes by:

  1. Stimulating the cells that break down bone (osteoclasts).
  2. Suppressing cells that build new bone (osteoblasts).

The result of this interference is bone fractures, bone pain, and the release of calcium from the bones into the blood. 


Complications in the Rest of the Body

Myeloma cells secrete monoclonal protein into the blood. The presence of this M-protein in the blood can cause tissue damage at distant sites. Monoclonal protein builds up in the tubules of the kidneys can cause kidney damage.

  • Monoclonal protein can also interfere with blood clotting and/or circulation.
  • Monoclonal proteins can affect nerve tissue and cause peripheral neuropathy, which is numbness, tingling, or pain in the hands and feet.


CRAB Criteria: Medical Problems Related to Myeloma

Health professionals rely on the CRAB criteria to diagnose multiple myeloma. CRAB is an acronym that stands for:

  • C: Calcium elevation 
  • R: Renal problems (kidney dysfunction) 
  • A: Anemia
  • B: Bone lesions 
Effects of Increased Myeloma Cells in the Bone Marrow

CRAB criteria
Cause Impact on Patient
C - Increase in blood calcium Release of calcium from damaged bone into bloodstream.
  • Mental confusion
  • Dehydration
  • Constipation
  • Fatigue
  • Weakness
  • Renal or kidney damage
R -Renal problems in kidney damage Abnormal monoclonal proteins produced by the myeloma cells are released into the bloodstream and can pass into the urine and produce kidney damage. High blood calcium, infections, and other factors can also cause or increase the severity of kidney damage.
  • Sluggish circulation
  • Fatigue
  • Mental confusion
A - Anemia Decrease in the number and activity of red blood cell-producing cells in the bone marrow.
  • Fatigue
  • Weakness
  • Shortness of breath
  • Rapid heartbeat
  • Swelling in legs
  • Dizziness
  • Headache
  • Chills
  • Change in appetite
  • Decreased libido
B - Bone Damage
  • Thinning (osteoporosis) or
  • Areas of more severe damage (called lytic lesions), fracture, or collapse of a vertebra. (Learn more at Bone Disease.)
The myeloma cells activate osteoclast cells, which destroy bone, and block osteoblast cells, which normally repair damaged bone.
  • Bone pain
  • Bone swelling
  • Fracture or collapse of a bone
  • Nerve or spinal cord damage
Additional types of organ dysfunction Local or systemic effects of myeloma, other than CRAB features.
  • Neuropathy (nerve damage)
  • Recurrent infections
  • Bleeding problems
  • Other individual problems
Abnormal immune function The myeloma cells reduce the number and activity of normal plasma cells capable of producing antibodies against infection.
  • Susceptibility to infection
  • Delayed recovery from infection

Learn More About Multiple Myeloma

The International Myeloma Foundation offers extensive information on multiple myeloma. You can visit our online resource library and download the information you need free of charge. You are also welcome to contact our InfoLine to talk with one of our compassionate professionals, they are well-equipped to answer your questions. 
 

What's Next?

 

For myeloma patients, tests are used for diagnosing your disease, discovering the type of myeloma you have, staging the disease, and monitoring your response to treatment.

What Is Multiple Myeloma?

Our bone marrow creates plasma cells that make antibodies, which play an important role in fighting off viruses and bacteria. Multiple myeloma causes the bone marrow to create dysfunctional antibodies and plasma cells. A malignant plasma cell or cancer cell is referred to as a myeloma cell.

Myeloma cells frequently grow in multiple patches or areas in the bone marrow, which is why "multiple" is part of the name. Plasma cell myeloma is another common name for the condition.

 


The International Myeloma Foundation medical and editorial content team

Comprised of leading medical researchers, hematologists, oncologists, oncology-certified nurses, medical editors, and medical journalists, our team has extensive knowledge of the multiple myeloma treatment and care landscape. 

Additionally, the content on this page is medically reviewed by myeloma physicians and healthcare professionals.

Last Medical Content Review: January 29, 2025

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