Factor X assays using chromogenic substrate S-2222

• Published in: American journal of clinical pathology Vol. 73; no. 3; pp. 400 - 402
• Main Authors: Girolami, A, Saggin, L, Boeri, G
• Format: Journal Article
• Language: English
• Published: England 01.03.1980
• Subjects: Blood Coagulation Tests; Factor X - analysis; Factor X Deficiency - blood; Factor X Deficiency - congenital; Factor X Deficiency - diagnosis; Humans; Hypoprothrombinemias - blood; Oligopeptides; Prothrombin Time
• ISSN: 0002-9173; 1943-7722
• DOI: 10.1093/ajcp/73.3.400

Factor X was assayed using chromogenic substrate S-2222 for four patients with severe factor X deficiency and for nine patients with homozygous or heterozygous factor X Friuli disorder. Factor X Friuli disorder is characterized by the presence of an abnormal factor X that is normally activated by Russell's viper venom, but is not activated by tissue thromboplastins. The levels of factor X found in factor X deficiency varied between 2 and 10% of normal and therefore were higher than those found in the same plasmas using "clotting" methods (1% or less than 1% of normal). The levels of factor X found in homozygous factor X Friuli patients varied between 4 and 11% of normal, and therefore were practically identical to those found by means of clotting methods that employed tissue thromboplastins (7-9% of normal). These values were definitely lower than those obtained using a Russell's viper venom and cephalin mixture as thromboplastin (82-92%). A similar pattern was observed for patients heterozygous for the abnormality. These findings indicate that "amidolytic" methods are not necessarily identical to clotting methods. Furthermore, they indicate that substrate S-2222 is not specific for factor X.