Abstract

Most fibrinogen replacement strategies focus on quantitative deficiencies. A thrombin time (TT) mixing study helped to assess qualitative defects caused by dysfibrinogens. Plasma samples were collected from non-anticoagulated subjects (n=6) meeting laboratory criteria for suspected dysfibrinogenaemia (TT > 22 s; fibrinogen activity <180) and from a control group. TT mixing studies were performed on subject plasma with increasing volumes of pooled normal plasma at 1:2, 1:4 and 1:5 dilutions. No subjects with dysfibrinogenaemia demonstrated a complete TT correction at 1:2, but 50% corrected at 1:4 and 100% at 1:5 dilution. Based on these data, a correction factor (CF), defined as the reciprocal dilution yielding complete correction, was incorporated into our clinical practice formula for fibrinogen dosing in patients with dysfibrinogenaemias. Our study incorporates TT mixing studies for assessment of dysfibrinogens. The addition of a mix-derived CF to classical formulae may better approximate dosing in patients with dysfibrinogenaemia.