Convenient and effective method for removing fibrinogen from serum specimens before protein electrophoresis

Abstract

Background: Fibrinogen in serum specimens can be misinterpreted on protein electrophoresis as a monoclonal protein. We evaluated selective precipitation of fibrinogen with ethanol. Methods: Pooled human plasma was mixed with absolute ethanol or saline (final concentrations of 40, 80, 100, 120, and 160 mL/L) and incubated at 4°C overnight or placed in an ice bath for 15 min. After centrifugation, the supernatants and resuspended pellets were used for protein electrophoresis and quantitative measurements of protein and fibrinogen. Results: The fibrinogen band was effectively eliminated from the electrophoretic pattern in the plasma samples treated with ethanol at 100 mL/L and incubated in an ice bath for 15 min without a significant change in immunoglobulin concentrations. The 100 mL/L ethanol did not noticeably change the electrophoretic pattern of monoclonal immunoglobulins. This approach allowed analysis of a sample collected from an arteriovenous shunt kept open with heparin. Conclusions: Ethanol, 100 mL/L, can selectively precipitate fibrinogen without significantly interfering with the immunoglobulins. The precipitation process can be completed in 15 min at 0-4°C and can avoid the need to obtain another blood sample. © 2003 American Association for Clinical Chemistry.