Which laboratory finding is characteristically elevated in multiple myeloma?

In multiple myeloma, a hallmark laboratory finding is the presence of a monoclonal gammopathy, which is identified through serum protein electrophoresis. This test reveals an abnormal spike, known as an M spike, characterized by an increase in a single type of immunoglobulin (either IgG, IgA, or a light chain). This results from the neoplastic proliferation of a single clone of plasma cells producing large quantities of the same immunoglobulin.

The significance of this finding lies in its direct correlation with the underlying pathophysiology of multiple myeloma. The proliferation of this monoclonal population of plasma cells leads to an excess of abnormal immunoglobulin in the serum, which can contribute to various complications associated with the disease, including renal impairment and increased risk of infections. Therefore, the presence of monoclonal gammopathy on serum protein electrophoresis is a distinctive diagnostic feature that supports the diagnosis of multiple myeloma.

The other laboratory findings, while potentially present in certain cases, do not characterize the disease as specifically as the elevated monoclonal gammopathy does. For example, increased white blood cell count and elevated liver enzymes might occur in various other conditions, and decreased serum albumin is not exclusive to