Discrepant fibrinogen values during thrombolytic therapy. Comparison of aca and Data-Fi results using immunofixation....

The authors compared aca and Data-Fi fibrinogen values and used a combination of plasma protein electrophoresis and immunofixation with anti-fibrinogen anti-serum to observe changes in fibrinogen from four patients receiving streptokinase (STK) therapy. For three patients, aca and Data-Fi values pre-STK and greater than or equal to 24 hours post-STK correlated well (r = 0.96, slope = 0.92, y-intercept = 2.3; n = 13 pairs); aca and Data-Fi values during STK therapy correlated poorly (r = 0.67, slope = 0.36, y-intercept = 4.1; n = 20 pairs), with aca values up to sixfold higher than Data-Fi. Protein electrophoresis and immunofixation showed loss of the discrete fibrinogen band during STK therapy; instead there was a diffuse electrophoretic zone of anti-fibrinogen reactive material having a slightly different mobility than intact fibrinogen; aca fibrinogen values were inconsistent with fibrinogen band absence. The remaining patient showed no change in the fibrinogen band. Clinically he showed no response to STK therapy. In nonresistant patients, STK results in the degradation of fibrinogen into a mixture of products (FDP), all sharing antigenic determinants with fibrinogen and at least one being still clottable. Our results exemplify loss of intact fibrinogen with persisting anti-fibrinogen reactive FDP during STK therapy. Discrepancies in aca versus Data-Fi results may be due to ways in which FDP interact with different methods--fibrometer versus turbidimetric.