Which of the following statements regarding the identification of monoclonal proteins by IFE is true?

The statement that both serum and urine must be examined when testing for a monoclonal gammopathy is accurate because many monoclonal proteins can be detected in both biological fluids. In the case of conditions such as multiple myeloma or other plasma cell dyscrasias, it is essential to analyze both serum and urine to identify the presence of monoclonal proteins, typically referred to as M proteins.

Serum protein electrophoresis (SPEP) is employed to identify and quantify these proteins in the serum. However, some monoclonal proteins are secreted exclusively in the urine, particularly light chains, which may not be detected in the serum. Therefore, 24-hour urine collection and urine protein electrophoresis (UPEP) are crucial components of the diagnostic process. Analyzing both fluids increases the likelihood of accurately identifying the presence of these proteins and helps in understanding the extent of the disease. This dual analysis is a standard practice in the clinical workup of suspected monoclonal gammopathies.