Background: Monoclonal gammopathy of undetermined significance is defined by the presence of: low serum and/or urine monoclonal protein level; less than 10% plasma cells in bone marrow; normal serum calcium, creatinine and hemoglobin levels; and no bone lesions on full skeletal X-ray survey.
Objectives: To study the necessity of bone marrow examination for the diagnosis and clinical course of MGUS[1].
Methods: We retrospectively screened the medical records of all patients in whom monoclonal protein was found in the serum during 2001–2002 in the medical laboratories of Sapir Medical Center. Asymptomatic patients who had serum monoclonal immunoglobulin G < 3.0 g/dl or IgA[2] < 2.0 g/dl or IgM < 1.0 g/dl without anemia, renal failure, hypercalcemia or any bone lesions on skeletal survey were eligible. Full records of patients who were evaluated in the hematology clinic were available (group 1). The remaining patients were followed by their family physicians; thus we had access only to their electronic files including laboratory results and new diagnoses (group 2). Demographic and clinical parameters as well as clinical course were evaluated.
Results: Both groups (57 and 255 patients, respectively) had similar demographic, laboratory and clinical characteristics. Bone marrow examination was performed in 30 of 57 patients (group 1): 16 were normal, 8 had an excess of normal plasma cells, and 6 had excess of pathologic plasma cells. However, only in two of the latter six could a diagnosis of multiple myeloma be established. All group 1 patients were followed for 22 ± 11 months and only two developed overt multiple myeloma. During the same period, 6 of 255 patients (group 2) were diagnosed as multiple myeloma and 3 as MGUS in other hospitals. The rest had a stable course with no change in their laboratory values.
Conclusions: Our findings suggest that bone marrow examination should not be performed routinely in patients who fulfill strict clinical and laboratory criteria of MGUS.