Tissue Extracts and their Sensitivity to Factor VII and Factor X

Summary Lung thromboplastins made by conventional methods are normally heavily contaminated with factor VII, due to interaction of tissue with plasma or serum, and calcium during their preparation. Factor X is consumed during this process, and the resulting thromboplastin is capable of detecting deficiency of factor X in a plasma sample. Lung thromboplastin may be prepared free from factor VII contamination, and such thromboplastin is extremely sensitive in detecting factor VII deficiency.