Serum neural cell adhesion molecule differentiates multiple myeloma from paraproteinemias due to other causes.

Serum neural cell adhesion molecule (NCAM) has been described as a prognostic marker in multiple myeloma (MM). Both C-reactive protein (CRP) and beta 2-microglobulin (beta 2M) are established prognostic markers in MM. We tested the diagnostic value of these markers in 212 serum samples of patients with paraproteinemia registered prospectively in a population-based registry. Sixty patients had MM and 152 had other monoclonal gammopathies (hematologic diseases [48], paraneoplastic disease [35], autoimmune disease [15], and monoclonal gammopathy of undetermined significance [56]). CRP and beta 2M had wide and overlapping ranges in all diagnostic categories. However, serum neural cell adhesion molecule (NCAM) was low (< 20 U/mL) in all but 4 of 152 nonmyeloma cases and high (> or = 20 U/mL) in 31 (52%) of the 60 MM cases. Two patients with non-Hodgkin's lymphoma, 1 with chronic lymphatic leukemia, and 1 with autoimmune disease had serum NCAM values between 20 and 30 U/mL. In a discriminant analysis in which serum NCAM, CRP, beta 2M, paraprotein type and concentration, hemoglobin, leukocyte and thrombocyte counts, creatinine, corrected calcium, lactate dehydrogenase, and alkaline phosphatase were included, paraprotein type and concentration and serum NCAM turned out to be the best combination of parameters predicting whether a patient had MM, with 89% of cases being correctly classified. Even without bone marrow and x-ray examinations, serum NCAM, in combination with paraprotein type and concentration, can differentiate between MM and nonmyeloma patients.