Optimizing the Use of Serum Immunofixation for the Detection of Monoclonal Components in Hypogammaglobulinemia: Insights From a Tertiary-Care Biochemistry Laboratory

Hypogammaglobulinemia is a heterogeneous immunologic abnormality that may result from primary antibody deficiencies, secondary causes, or hematologic malignancies. Although serum protein electrophoresis (SPEP) is routinely used for initial evaluation, reduced γ-globulin levels may mask small monoclonal components, limiting the sensitivity of SPEP alone. Serum immunofixation electrophoresis (IFE), with its superior analytical resolution, may therefore be useful in the diagnostic assessment of hypogammaglobulinemia. The primary objective is to determine the diagnostic yield of systematic serum IFE in adult patients with hypogammaglobulinemia detected by SPEP, defined here as the proportion of patients in whom IFE identified a monoclonal or oligoclonal immunoglobulin abnormality not apparent on SPEP alone. The secondary objectives are to describe the immunochemical patterns identified (monoclonal vs. oligoclonal) and to characterise the detected isotypes (heavy-chain class and light-chain type), including biclonal and light-chain-only profiles. A retrospective descriptive study was conducted over a 12-month period (March 2023-March 2024) at the Central Biochemistry Laboratory of Mohammed VI University Hospital, Oujda, Morocco. Adult patients (≥16 years) presenting with hypogammaglobulinemia, defined as γ-globulin