Myeloma (also called multiple myeloma) is a blood cancer of the plasma cells. Plasma cells are mature white blood cells that produce antibodies which help fight infection. In myeloma the plasma cells are abnormal and are called myeloma cells. The myeloma cells accumulate in the bone marrow, where they crowd out healthy blood cells. Rather than produce helpful antibodies, the cancer cells produce abnormal non-functional antibodies called paraproteins that can be found in the blood and urine and cause kidney problems. The finding of a paraprotein in blood is a hallmark of myeloma.

The paraprotein cannot fight infection properly and can also reduce the amount of normal antibodies being made. Myeloma cells can spread from the bone marrow into the bone itself and cause damage to bone tissue. Several bones can be affected and for this reason, myeloma is often called multiple myeloma. The average at which myeloma is diagnosed is 65-70 years. It is much rarer in younger adults, with just 2% of cases occurring in those under 40 years of age. It is estimated that there are 200-250 new cases of myeloma each year in Ireland. Doctors divide myeloma into groups that describe how rapidly or slowly the disease is progressing. Asymptomatic or smouldering myeloma progresses slowly and has no symptoms even though the patient has the disease. Symptomatic myeloma has related symptoms such as anaemia, kidney damage and bone disease.