Method comparison for serum protein electrophoretic M‐protein quantification: Agarose gel electrophoresis and capillary zone electrophoresis in canine and feline sera

Abstract

Background: Densitometric quantification of myeloma paraproteins (M-proteins) is used to monitor secretory myeloma related disorders in humans and dogs. The previous work in dogs used agarose gel electrophoresis (AGE) but did not establish if other methods of serum protein electrophoresis, such as capillary zone electrophoresis (CZE), were comparable. Objectives:We aimed to determine if the densitometric quantification of M-proteins using CZE would yield results comparable to AGE methods.Methods: Fifty-one serum samples from 22 dogs and 18 cats with confirmed monoclonal gammopathies and previously performed AGE were evaluated using CZE on a Sebia Minicap system. Samples were run in duplicate, and their M-proteins were densitometrically measured using the corrected perpendicular drop method previously described. Human-based quality control samples were used to determine the inter-run coefficient of variation (CV). Patient samples were used to calculate the intra-run CV.Method comparison was performed using simple linear regression, Passing-Bablok regression, and Bland-Altman analyses, and Medx evaluations.Results: Inter-run and intra-run CVs for CZE were 3.71%-7.65% and 2.89%-4.74%, respectively. Simple linear regression demonstrated an excellent correlation (r > 0.98).Passing-Bablok regression was compatible with the presence of proportional bias in the entire population, and Bland-Altman plots revealed a proportional bias in the feline cases. The Medx evaluation suggested that the two methods did not perform similarly in clinical samples with poor performance at a decision limit of 0.5 gm/dL. Conclusions: Capillary zone electrophoresis is an acceptable method for M-protein densitometric quantification in canine and feline sera but cannot be used interchangeably with AGE-based evaluations.

Serum protein electrophoresis in European mink ( Mustela lutreola ): reference intervals and comparison of agarose gel electrophoresis and capillary zone electrophoresis

“…CZE and AGE produce similar pherograms to those of other mammals, particularly dogs and cats (Giordano and Paltrinieri 2010 ; Jeffries et al. 2021 ). The differences observed in the peaks were due to the use of different software programs to identify the inflection points.…”

“…Both techniques have been used in clinical practice (Giordano and Paltrinieri 2010 ; Jeffries et al. 2021 ) and in wild species such as green turtles ( Chelonia mydas ) (Toonder et al. 2020 ), bald eagles ( Haliaeetus leucocephalus ) (da Fonseca et al.…”

“… 2020 ), dogs ( Canis lupus familaris ) (Giordano and Paltrinieri 2010 ; Jeffries et al. 2021 ), mice ( Mus musculus ) (Crivellente et al. 2008 ), and humans ( Homo sapiens ) (Lissoir et al.…”

Spurious capillary zone electrophoresis pattern in hypercholesterolemic dogs

“…20 Even though CZE is more expensive than the other methods, it offers some advantages, such as higher resolution, 18 high degree of automation, and similar sensitivity to AGE in detecting monoclonal peaks. 22…”

“…20 Even though CZE is more expensive than the other methods, it offers some advantages, such as higher resolution, 18 high degree of automation, and similar sensitivity to AGE in detecting monoclonal peaks. 22 In SPE, albumin is the most prominent peak on the anodal side of the electrophoretogram, 40 and its concentration can be quantified by converting its electrophoretic percentage from the total protein concentration measured by the biuret method. 32 However, albumin concentration can also be measured using spectrophotometric methods.…”