Serum protein electrophoresis: reptilase treatment is superior to ethanol precipitation for specific removal of fibrinogen from heparinized plasma samples.

Qui et al. (1) propose a method to remove fibrinogen from serum specimens by precipitation with absolute ethanol for use in protein electrophoresis (PE). The authors recommend this method as highly selective and inexpensive. We read the article with great interest, as a possible alternative to the method incorporating reptilase (2) that is routinely used in our laboratory, which uses plasma for PE when no serum sample from a patient is available. For method evaluation, we used 20 samples from laboratory staff with normal concentrations of fibrinogen, as well as 20 samples from patients with plasma fibrinogen of 7.4–12.9 g/L. As suggested by Qiu et al. (1), we used ethanol at a final concentration of 100 mL/L. The samples were incubated for 15 min on ice and centrifuged at 1100 g for 5 min at 4 °C. The supernatant was used for PE. The pellet containing fibrinogen was resuspended in 0.2 mL of saline (9 g/L NaCl) and stored for further analysis. For comparison, we used reptilase (STA Reptilase; Diagnostica Stago, Roche Diagnostics) at a dilution of 1:10 in patient plasma. After incubation at 37 °C for 5 min and centrifugation for 5 min at 20 590 g , … [↵][1]bAuthor for correspondence. [1]: #xref-corresp-2-1

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