Cerebrospinal fluid monoclonal gammopathy in multiple myeloma and Waldenström's macroglobulinemia.

Serum ratios of monoclonal immunoglobulin (Ig) to total protein, monoclonal immunoglobulin to albumin, CSF/serum Ig-albumin index, and CSF to serum monoclonal immunoglobulin were obtained in 21 patients with multiple myeloma and 2 with Waldenström's macroglobulinemia. Twelve patients (3 with CNS complications) showed CSF monoclonal proteins similar to their serum. CSF IgA levels above 10 mg/dl, IgG levels above 25 mg/dl, CSF-serum IgG ratios above 0.0034 and CSF-serum IgA ratios above 0.0051 were seen in patients with neurologic complications. Our preliminary data may signal early CNS involvement in multiple myeloma.