Abstract: The present invention is to provide a means for the stabilization of thrombin and a stabilized thrombin-containing composition having a good reproducibility of the measurement. There are provided a means for the stabilization of thrombin, characterized in that, effective amount(s) of one or more which is/are selected from calcium ion, surfactant and protein is/are contained and a stabilized thrombin-containing composition as well. There are also provided a means for the stabilization of thrombin where an effective amount of a water-soluble organic acid is jointly used in addition to the above and a stabilized thrombin-containing composition as well. There is further provided a thrombin-containing composition having an extremely high measurement reproducibility using thrombin and stabilizer for thrombin where one or more high-molecular polysaccharides or synthetic polymers is/are contained in the above-mentioned stabilized thrombin-containing composition.

Abstract: This invention provides a novel thromboplastin reagent having high measurement sensitivity. Thus, an effective amount of amino acid or derivative thereof having such a function that an ISI (international sensitivity index) of a composition of thromboplastin showing an ISI of more than 1.0 is made nearer 1.0 is added whereby a thromboplastin having a high measurement sensitivity is provided. To be more specific, sodium glutamate is added in an effective amount.