Multiple myeloma can affect the bones, the red blood cells, and the kidneys. It can also affect the immune response, leading to repeated and sometimes severe infections. In this section, learn more about possible medical conditions related to multiple myeloma.

Possible Urgent Problems at Diagnosis

Some patients have urgent problems at diagnosis that require medical attention before systemic therapy for myeloma begins. Vertebral compression fractures, damage to the nerves of the spinal cord, infections, and kidney failure are all emergency medical problems.

  • Because the bones of the spine (the vertebrae) are often affected by myeloma, and because the spinal cord runs through the vertebrae, painful vertebral fractures can result. (See the IMF publication Understanding Treatment of Myeloma-Induced Vertebral Compression Fractures.)
  • Myeloma tumors (plasmacytomas) growing in the vertebrae can press on spinal nerves, and compression of motor nerves can cause paralysis.
  • Breakdown of calcium released from bones can result in hypercalcemia, a high level of calcium in the blood.
  • Both hypercalcemia and high levels of monoclonal protein in the blood can seriously affect the kidneys, causing kidney failure.
  • MM impairs the immune response, sometimes resulting in severe infections. (See the IMF publication Understanding the Immune System in Myeloma.)


Effects in the Bone Marrow

  • All the blood cells — white blood cells, red blood cells, and platelets — are made in the bone marrow. When myeloma grows in the bone marrow, the effects include a reduction in blood cell production. Anemia, a low level of red blood cells, is an early and common sign of multiple myeloma.
  • Cells in healthy bone marrow maintain our skeletons in an ongoing, balanced process of bone breakdown and bone build-up. MM cells in the bone marrow stimulate the cells that break down bone (osteoclasts) and suppress cells that build new bone (osteoblasts). The result is bone pain, fractures, and the release of calcium from the bones into the blood.


Effects Outside the Bone Marrow

Monoclonal protein secreted by myeloma cells into the blood can cause tissue damage at distant sites, including:

  • Monoclonal light chain protein can build up in the tubules of the kidneys, causing kidney damage.
  • Monoclonal protein can interfere with blood clotting and/or circulation.
  • Monoclonal protein deposits on nerve tissue can cause peripheral neuropathy, numbness, tingling, or pain in the hands and feet.


CRAB Criteria: Medical Problems Related to Myeloma

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
B - Bone Damage
  • Thinning (osteoporosis) or
  • Areas of more severe damage (called lytic lesions), fracture, or collapse of a vertebra
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
  • 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

What Is Multiple Myeloma?

Multiple myeloma is a cancer of the bone marrow plasma cells. It is synonymous with "myeloma" and "plasma cell myeloma." Plasma cells make antibodies against infectious agents such as viruses and bacteria. A cancerous or malignant plasma cell is called a myeloma cell. Myeloma is called “multiple” because there are frequently multiple patches or areas in bone marrow where it grows.

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