What is the defining feature of monoclonal gammopathy on electrophoresis?

• A. Only one gamma fraction increased
• B. All gamma fractions increased
• C. Gamma fractions decreased
• D. Gamma fractions unchanged

Answer: (A)

Monoclonal gammopathy on electrophoresis is defined by a sharp, well-defined spike in the gamma region, reflecting a single immunoglobulin produced by a clonal population of plasma cells. This single, narrow M-spike stands out against the rest of the gamma region and indicates monoclonality. In contrast, a polyclonal gammopathy shows a broad, diffuse elevation across many gamma globulins, not a single narrow peak. So the defining feature is that only one gamma fraction increases, producing that isolated monoclonal spike.