Thrombotest Dilution Curve

With much interest I read the remarks of Dr. A. Girolami on the paper of Briet et al. He is essentially right in stating that a plasma deficient in one coagulation factor will show in the thrombotest dilution curve a line intercepting the ordinate at a point higher than that for nor-mal plasma. The reason for this phenomenon is simple. With normal plasmas or plasmas in which the rate limiting clotting factors (iI, VII, X) are deficient to about the same extent ex-trapolation to the ordinate is extrapolation to a situation in which all three clotting factors are present in infinite amounts. When one of the factors is lacking- in the most extreme case absent- extrapolation to infi-nite concentrations will still represent a situation in which the lacking factor is rate limiting, i. e. a high clotting time. Careful reading of our articles "Kinetic aspects of the interaction of coagulation factors" I-VII (Thrombosis and Haemostasis 1965-1977) and of the literature cited therein will show that from the beginning we have been aware of this fact. The detection of inhibitors by the thrombotest dilution curve is only possible when no specific deficiencies exist. The remarks of Dr. Girolami are not superfluous though, as I have observed that time and again aberrant dilu