[Beacon Staff]

–► Criteria for a smoldering multiple myeloma diagnosis

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

The following criteria must be met for a diagnosis of smoldering multiple myeloma:

First, there must be evidence that there are clonal plasma cells present in the body. Clonal plasma cells are a particular kind of abnormal plasma cells. The evidence of clonal plasma cells may be any one or more of the following:

• A serum M-spike (monoclonal protein, paraprotein, or abnormal protein band) of at least 3.0 g/dL (30 g/l), or
• Urinary monoclonal protein of at least 500 mg per 24 hours, or
• Clonal bone marrow plasma cell percentage that is from 10 to 60 percent

Second, for a smoldering multiple myeloma diagnosis, there must be NO "myeloma defining events" (see below), and there must be no amyloidosis.

There are seven possible myeloma defining events (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.

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

Generally when someone is undergoing tests to determine if they have smoldering multiple myeloma, they also may be suspected of having either symptomatic (active) multiple myeloma, or a condition known as MGUS (monoclonal gammopathy of undetermined significance). Thus, these links also may be helpful:

Criteria for a (symptomatic) multiple myeloma diagnosis
Criteria for an MGUS diagnosis