title: Study on a new chromogenic substrate for the prothrombin time determination.
abstract: The aim of our study was to evaluate the possibility of using a chromogenic substrate for the prothrombin time determination. The reagent used by us (Chromoquick) is composed of a human placenta thromboplastin and chromogenic substrate (Tos-Gly-Pro-Arg-5-amino-2-nitrobenzoic acid-isopropylamide), calcium chloride and a buffer. Normal subjects, patients with liver disease, patients on oral anticoagulant therapy, patients on heparin therapy, heterozygous and homozygous patients for prothrombin complex defects and other miscellaneous conditions have been investigated. The results of chromoquick have been related with standard prothrombin time obtained using a human placenta thromboplastin (Thromborel) and rabbit brain and lung thromboplastin (Simplastin). The normal range was 18-23 s for chromoquick and 13.5-15.5 s for the standard prothrombin times using Thromborel and Simplastin. In all groups of patients examined we noticed a significant correlation between the chromogenic and the classic prothrombin times with r values varying between +0.505 and +0.947. The statistical significance resulted from p values varying between less than 0.05 and less than 0.001. Only in the case of some heterozygotes for prothrombin complex factor defects the values obtained have not been unequivocal in the sense that in a few instances the heterozygotes seemed to escape detection. Therefore, it seems that the introduction of chromogenic substrates in laboratory practice for the prothrombin time determination is possible and can offer considerable advantages like standardization and automation. The only disadvantage may be caused by costs involved.
mesh_terms: D000074:Acenocoumarol / Q000009:adverse effects; D000284:Administration, Oral; D000328:Adult; D002863:Chromogenic Compounds; D005260:Female; D006402:Hematologic Diseases / Q000097:blood; D006801:Humans; D008107:Liver Diseases / Q000097:blood; D008297:Male; D008875:Middle Aged; D009842:Oligopeptides; D011517:Prothrombin Time
chemical_list: D002863:Chromogenic Compounds; D009842:Oligopeptides; C055937:tosyl-glycyl-prolyl-arginyl-5-amino-2-nitrobenzoic acid; D000074:Acenocoumarol