Serum Protein Electrophoresis (SPEP) is used in the evaluation of which disease?

• A. Osteoarthritis
• B. Gout
• C. Systemic sclerosis
• D. Multiple myeloma

Answer: (D)

SPEP is most informative when looking for a monoclonal gammopathy from a plasma cell disorder. In multiple myeloma, malignant plasma cells often produce a single type of immunoglobulin, so the serum shows a sharp, narrow spike—the M-protein—in the gamma region. This pattern flags a plasma cell dyscrasia and prompts further testing (like immunofixation to identify the specific immunoglobulin and light-chain type, and additional assessments for disease extent).

The other conditions listed are not defined by a monoclonal immunoglobulin pattern on SPEP. Osteoarthritis and gout are diagnosed mainly through clinical features and other tests (like imaging and uric acid levels), while systemic sclerosis relies on autoantibodies and characteristic fibrosis rather than a monoclonal protein. So the presence of an M-spike on SPEP points most clearly to multiple myeloma. If no M-spike is seen, other considerations (like non-secretory myeloma or MGUS) may be explored with additional tests.