Outcomes of discretionary laboratory requesting of serum protein electrophoresis

Discretionary laboratory requesting of serum protein electrophoresis (SPE) is widespread throughout the UK despite limited evidence to support clinical usefulness. We aimed to examine the clinical usefulness of discretionary SPE requesting on serum samples with globulins>45 g/L by documenting the number of discretionary tests performed and the number of paraproteins identified in an audit period, by determining if such findings led to further investigation/specialty referral, and by identifying the final diagnosis and subsequent management of these patients.

A retrospective one-year audit from July 2002 to June 2003 was carried out using information from biochemistry databases and review of medical records.

Of 1332 discretionary SPEs performed in one year, 72 paraproteins were identified (5.4%). Further clinical information could be obtained in 66 cases. Appropriate follow-up occurred in 84% of cases. The most common diagnosis was monoclonal gammopathy of undetermined significance (56%). Eighteen percent of patients with an identified paraprotein were diagnosed with B-cell malignancies that warranted treatment. A further 6% progressed to requiring treatment during follow-up.

Using screening criteria of serum globulins>45 g/L, one in 20 discretionary laboratory requests resulted in a clinically relevant finding. These results suggest such requesting is worthwhile and should aid future debate on the appropriateness of this practice.