An underestimated old friend: Serum protein electrophoresis in the differential diagnosis of glomerulopathies

Background: Serum protein electrophoresis (SPEP) is an easy test separating serum proteins based on their physical and chemical properties. Although it is frequently used in the differential diagnosis of multiple myeloma and various chronic inflammatory diseases, its value in the etiologic classification of glomerular diseases has yet to be studied. Material and Methods: We retrospectively reviewed the medical records of patients who underwent renal biopsy from 2008 to 2016 at our institution. We excluded patients who can not be classified as primary (PGn) or secondary glomerulonephritis (SGn). Univariate and multivariate logistic regression analyses were performed for the prediction of SGn. Results: Four hundred thirty-two patients were included in the study. Of those, 57.9% had PGn. Rheumatological diseases, malignancies, and infections were the most common etiologic causes of SGn, accounting for nearly 75%. Univariate analysis revealed that alpha-1 (α1), gamma (Ɣ), and albumin fractions significantly differ between PGn and SGn groups. ROC curve analysis determined the cut-off value of (α1*Ɣ)/albumin ratio as 1.48. Multivariate analysis revealed that total serum protein and (α1*Ɣ)/albumin ratio were significantly independent predictors for SGn (p=0.020 and p