Abstract: Provided is a method by which a titer of a coagulation factor inhibitor can be measured simply and in a short time. The present invention relates to a method for measuring a titer of a coagulation factor inhibitor. The method includes: preparing a mixed specimen containing a subject blood specimen and a normal blood specimen; heating the mixed specimen and acquiring a coagulation reaction curve for the heated mixed specimen; acquiring a coagulation reaction curve for the mixed specimen that has not been heated; calculating a parameter related to the coagulation reaction curve of the mixed specimen that has not been heated as a first parameter; calculating a parameter related to the coagulation reaction curve of the heated mixed specimen as a second parameter; and calculating a titer of a coagulation factor inhibitor in the subject blood specimen on the basis of the ratio or the difference between the first parameter and the second parameter.

Abstract: A plasmin solution, comprising:(A) plasmin, and (B) the following component (B-1), (B-2) or (B-3):(B-1) an oligopeptide comprising at least two amino acids bonded to each other, where the two amino acids are selected from the group consisting of lysine, arginine, glycine, alanine, aspartic acid and methionine;(B-2) at least two amino acids selected from the group consisting of lysine, arginine, glycine, alanine, aspartic acid and methionine; or(B-3) an amino acid selected from the group consisting of lysine, arginine, glycine, alanine, aspartic acid and methionine, and a polyhydric alcohol. This solution is stable, maintains plasmin activity even after long-term storage, and can be used as a reagent for quantitatively measuring .alpha.2PI.