SPEP, UPEP, Immunofixation, and Free Light Chains: The Myeloma Workup NPs Need to Know
SPEP, UPEP, Immunofixation, and Free Light Chains: The Myeloma Workup NPs Need to Know The dipstick misses light chains. SPEP finds the spike. UPEP catches what spills into the urine. And free light chains changed everything. This post complements the immunoglobulin levels post and the SPEP section from the autoimmune serologic review. When you suspect a monoclonal gammopathy—whether it's MGUS, multiple myeloma, Waldenström's, or amyloidosis—you need to understand the full diagnostic panel: SPEP, UPEP, immunofixation, and serum free light chains. The Diagnostic Panel Test What It Does When to Order SPEP (Serum Protein Electrophoresis) Separates serum proteins by charge. Detects and quantifies an M-spike (monoclonal protein) in the gamma region. Suspected myeloma, MGUS screening, unexplained elevated total protein, unexplained proteinuria, polyclonal gammopathy evaluation Immunofixation (IFE) Identifies the heavy chain (IgG, IgA, IgM) and light chain (kappa or lambda) type of ...