title: A simple method for the derivation of the international normalized ratio for the reporting of prothrombin time results.
abstract: In order to harmonize the prothrombin time (PT) reporting systems, the World Health Organization, in collaboration with the International Committee on Thrombosis and Hemostasis, and the International Council on the Standardization in Hematology proposed a reporting system, the so-called international normalized ratio (INR). As the calculation of the INR depends on mathematical formula requiring a special calculator or mathematic tables, its derivation is associated with some difficulties and errors. In this article a nomogram is presented, by which derivation of the INR from different PT reporting methods can be easily done within a few seconds.
mesh_terms: D000925:Anticoagulants / Q000008:administration & dosage / Q000627:therapeutic use; D016903:Drug Monitoring; D006405:Hematology / Q000592:standards* / Q000706:statistics & numerical data; D006801:Humans; D007391:International Cooperation; D008433:Mathematics; D011517:Prothrombin Time; D014859:Warfarin / Q000008:administration & dosage / Q000627:therapeutic use; D014944:World Health Organization
chemical_list: D000925:Anticoagulants; D014859:Warfarin