Myeloma, also known as multiple myeloma, is a cancer of the bone marrow which affects the plasma cells, a type of blood cell.

Normally, new plasma cells are produced to replace old, worn-out cells in an orderly and controlled way. They produce antibodies, also called immunoglobulins, to help fight infection.

However, in myeloma, the process becomes out of control and large amounts of abnormal plasma cells are produced releasing only one type of abnormal antibody.  This is known as paraprotein or M protein – which has no useful function and can’t fight infection effectively.

The abnormal plasma cells release chemicals that impair the normal breakdown and remodeling of bone and this can cause bone thinning, which in turn causes pain and sometimes fractures. An area of damaged bone is known as a lytic lesion.

The production of paraprotein and M protein can also cause damage to the kidneys (renal impairment) which in some cases can be enough to require kidney dialysis. Kidney impairment and the level of myeloma cells in the bone marrow also impair the production of red blood cells causing anaemia.

There are several types of myeloma which are classified depending on the type of immunoglobulin (Ig) produced by the myeloma cells. Around 1 in 3 people have a type of myeloma that produces light chains only. This is called light chain or Bence Jones myeloma. A rare type of myeloma, non-secretory myeloma, produces little or no immunoglobulin.

The type of myeloma you have doesn’t usually affect the treatment you’re offered but it can influence how the disease will affect you.

There are some other conditions that affect the plasma cells and can sometimes develop into myeloma.

The two most common are MGUS (monoclonal gammopathy of unknown significance) and smouldering myeloma, which is also known as indolent or asymptomatic myeloma. MGUS is a non-cancerous condition that has a small risk of developing into myeloma. Smouldering myeloma is when you have enough myeloma cells in the bone marrow to signify myeloma but these cells are not affecting other parts of your body like kidneys, bones or bone marrow function.

If you’re diagnosed with either of these conditions, you’ll be monitored with blood tests, but may not need to have any treatment unless the condition progresses.

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