[Beacon Staff]

–► Criteria for a multiple myeloma diagnosis

by Beacon Staff on Sat Nov 01, 2014 10:02 pm

The criteria for a diagnosis of multiple myeloma are as follows:

First, there must be clear evidence that clonal plasma cells, which are a particular kind of abnormal plasma cells, are being produced and building up in the body. In particular,

• At least 10 percent of the cells in the bone marrow must be clonal plasma cells, OR
• There must be biopsy-based evidence of a plasma tumor ("plasma­cytoma") in the bones or elsewhere in the body.

Second, there must be at least one "myeloma defining event" (MDE). There are seven possible MDEs, divided into two categories:

1. MDEs That Are Signs Of Organ Damage (the so-called "CRAB" criteria):

• Hypercalcemia - Serum calcium more than 1 mg/dL (0.25 mmol/L) higher than the upper limit of normal, or more than 11 mg/dL (2·75 mmol/L)
• Kidney (renal) damage - Serum creatinine greater than 2 mg/dL (177 μmol/L) or creatinine clearance less than 40 mL per min (measured, or estimated by validated equations)
• Anemia - Hemoglobin level of 2.0 g/dL or more below the lower limit of normal, or a hemoglobin value of less than 10.0 g/dL
• Bone lesions - One or more lytic lesions as determined by an x-ray survey, CT scan, or PET-CT scan

2. MDEs That Are Biomarkers Of Malignancy:

• Clonal bone marrow plasma cell percentage of 60 percent or more
• Kappa-lambda free light chain ratio that is either greater than or equal to 100, or less than or equal to 0.01
• At least 2 focal lesions, each greater than 5 millimeter in size, on MRI studies

If the above criteria are fulfilled, the patient's disease is considered to be "symptomatic", or "active", multiple myeloma, which generally is treated with some combination of anti-myeloma drugs.

Note, however, that some physicians may choose to "watch and wait", rather than treat, a patient who fulfills the criteria for a multiple myeloma diagnosis, but does so only because they have a biomarker of malignancy (one of the last three MDEs), rather than signs of organ damage (the first four MDEs).

The MDEs that are signs of organ damage are often described as the "CRAB" criteria for a multiple myeloma diagnosis:

• Elevated levels of Calcium in the blood
• Evidence of Kidney (Renal) damage
• Anemia
• Bone damage

Even if someone does not meet the criteria for a multiple myeloma diagnosis, they may meet the criteria for a diagnosis of smoldering multiple myeloma, or for MGUS (monoclonal gammopathy of undetermined significance). Thus, these links may be helpful to some:

Criteria for a smoldering multiple myeloma diagnosis
Criteria for an MGUS diagnosis

For more information about the the criteria for a multiple myeloma diagnosis, particularly how they have been updated from what they were 10 or 15 years ago, please see this article:

Rajkumar, SV, "New Criteria For The Diagnosis Of Multiple Myeloma And Related Disorders," The Myeloma Beacon, Oct 26, 2014