We report a patient with MGUS whose plasma GA concentration was falsely decreased by M protein when blood was drawn in a heparin sodium-containing tube.
Fifty-nine of 103 patients with M-protein level < 3000 mg/dL in serum or 500 mg/24 h in urine and diagnosed with monoclonal gammopathy of undetermined significance (MGUS) based on smear alone were reclassified as smoldering MM when reassessed using CD138-stained biopsy/clot sections.
A new risk stratification system to determine the prognosis of MGUS using the size and type of M protein, and the serum free light chain assay is discussed.