A heightened risk of infection, bone fractures, kidney failure and blood disorders, such as anemia, are all common complications of multiple myeloma. Careful monitoring for possible complications is a vital part of myeloma treatment.

One of the earliest symptoms of multiple myeloma is pain in the lower back and ribs. This pain results from tiny bone fractures caused by the gradual deterioration of bone tissue. As the cancer progresses, the bones become progressively weaker, leading to more fractures and osteoporosis.

Bone fractures can be especially serious when they occur in the spinal vertebrae. The vertebrae may compress, trapping or damaging nerves. Spinal cord compression can cause severe pain. In extreme cases, paralysis may result from nerve damage.

As bone deterioration continues, high levels of calcium begin to build up in the blood. This buildup can lead to a number of kidney problems, including kidney stones and kidney failure. A lack of red blood cells, or anemia, is also a common complication: overproduction of plasma cells in the bone marrow leads to a reduction in red blood cells.

Anemia may also be caused by a lack of erythropoietin, a hormone produced mainly in the kidneys. Kidney damage caused by myeloma may interfere with erythropoietin production.

People living with multiple myeloma have a heightened risk of infection. The abnormal plasma cells eventually "crowd out" other normal plasma cells, thereby reducing the broad range of antibodies normally available to fight disease. The risks of pneumonia and other infections rise as a result.

The kidneys are susceptible to a number of myeloma complications: almost a quarter of all cases of multiple myeloma result in eventual kidney failure. Hypercalcemia results in more blood borne calcium than the kidney can safely filter out. The strain causes eventual kidney damage.

Although rare, MM can result in amyloidosis, a state in which amyloid protein deposits build up in the kidneys, impairing organ function. Amyloid deposits can occur in any organ, but the kidneys appear to be especially susceptible.

Pyelonephritis, or kidney infection, can also damage the organ and cause eventual kidney failure. Pyelonephritis is a bacterial infection that causes kidney inflammation. The increased risk of infection due to myeloma puts people living with the disease at greater risk for pyelonephritis.