Doctors who suspect myeloma will conduct a series of blood and urine tests to check blood counts and kidney function in addition to protein, calcium and antibody levels. If these numbers suggest that myeloma is present, doctors will take a bone marrow biopsy. This can be done by inserting a needle into the back of the pelvic bone and taking out a core — approximately the size of the tip of a lead pencil— that contains a small amount of marrow. This allows a pathologist to look for myeloma cells.

An X-ray, MRI, CT or positron emission tomography scan can sometimes show bone changes or destruction caused by myeloma.

An echocardiogram might be used to check heart function, which can be affected by myeloma.

To diagnose myeloma, a doctor must find malignant plasma cells or 10% plasma cells in the bone marrow and at least one of the following: high blood calcium level, poor kidney function, anemia, holes or lesions in the bones, a specific level of increase in one type of light chain antibody fragment in the blood, or 60% or more plasma cells in the bone marrow.

Myeloma is classified in stages 1 through 3, with 3 having spread the farthest and representing the highest risk. Additional genetic and chromosomal testing can help determine treatment.