Location of monoclonal peak as a tool in checking specimen integrity

Objectives Serum protein electrophoresis is a commonly used test in the diagnosis and follow-up of patients with monoclonal gammopathies. The practice of documenting the location of the peak may serve as delta check flags in SPEP samples. Methods We report on the inconsistent finding on two tests performed about three months apart. The inconsistency was discovered due to recognition of the change in the location of the monoclonal immunoglobulin on protein electrophoresis. Results Repeat testing with a third specimen revealed that the first test was run on a wrong specimen. Conclusion Recording the location of the monoclonal spike is recommended to serve as an additional “delta” check.