Special Protein Studies

The Special Protein Laboratory performs:

• Protein electrophoresis of serum and urine with quantitation of fractions and any monoclonal protein peak (eg, M-spike)
• Immunofixation electrophoresis of serum with monospecific antisera to IgG, IgA, IgM, kappa, and lambda
• Immunofixation electrophoresis is used to screen sera for monoclonal IgD and IgE in all initial studies in patients in whom a monoclonal light chain is found.
• Quantitation of IgG, IgA, IgM, and IgD
• Quantitation of serum immunoglobulin kappa- and lambda-free light chains
• Measurement of serum viscosity on sera with large amounts of IgM, IgG, or IgA monoclonal proteins
• Immunofixation on urine specimens with monospecific kappa and lambda antisera and appropriate heavy-chain antisera as indicated by the serum
• Cryoglobulin studies on sera and plasma (cryofibrinogen)

The demonstration of a monoclonal protein in the serum or urine raises the possibility of a neoplastic or potentially neoplastic process. The differential diagnosis includes:

• Multiple myeloma
• Monoclonal gammopathy of undetermined significance (benign monoclonal gammopathy)
• Primary systemic amyloidosis
• Waldenström’s macroglobulinemia
• Lymphoproliferative syndromes
• Heavy-chain diseases