[Antithrombin III dosage using the chromogenic substrate Tos-Gly-Pro-Arg-NAN, in several pathological situations].
Functional methods for ATIII determination are essential for the diagnosis of deficiencies of this important thrombin inhibitor.


OBJECTIVE
The aim of this work was standardize the method for ATIII level determination in plasma, in microplates.


METHODS
ATIII levels were measured, using the chromogenic substrate Tos-Gly-Pro-Arg-NAN, which is specific for thrombin, and which has been sinthesized at the Biophysical Department of the Escola Paulista de Medicina of the Federal University of São Paulo, Brazil.


RESULTS
Among 21 patients with deep venous thrombosis (DVT), 20 had ATIII levels above 70% (113 +/- 22%). A 22 year-old female patient, who had recurrent DVT and a familiar DVT antecedent, had a congenital ATIII deficiency (56%). ATIII levels were normal in 6 patients with von Willebrand disease (109 +/- 28%), as expected. In 20 patients with severe hepatic failure, it has been found reduced ATIII levels (42 +/- 19%), since this inhibitor is produced by the liver. In 3 patients with sepsis and DIC, ATIII levels have also been reduced (45 +/- 5%) owing to consumption during blood coagulation activation. There was a significant correlation between ATIII levels and the prothrombin time, as well as the factor V levels, and both are good parameters to assess hepatic function and to monitor DIC. There was a significant correlation between ATIII levels measured using the chromogenic substrate Tos-Gly-Pro-Arg-NAN and those measured using S-2238, produced by Kabi Laboratories.


CONCLUSIONS
This method for ATIII determination in plasma is easy to perform and it can detect ATIII deficiency in patients with hepatic failure, disseminated intravascular coagulation and thrombophilia.
Lourenço
D M
DM
Disciplina de Hematologia e Hemoterapia da Universidade Federal de São Paulo.
Noguti
M A
MA
Juliano
L
L
D000328:Adult; D000990:Antithrombin III / Q000032:analysis* / Q000096:biosynthesis; D002863:Chromogenic Compounds; D004211:Disseminated Intravascular Coagulation / Q000097:blood* / Q000175:diagnosis; D005260:Female; D006801:Humans; D011517:Prothrombin Time; D018709:Statistics, Nonparametric; D013924:Thrombophlebitis / Q000097:blood*; D014842:von Willebrand Diseases / Q000097:blood*
D002863:Chromogenic Compounds; D000990:Antithrombin III
Dosagem da antitrombina III usando o substrato cromogênico Tos-Gly-Pro-Arg-NAN, em diversas situações patológicas.