PT  - JOURNAL ARTICLE
AU  - Poller, Leon
AU  - Ibrahim, Saied
AU  - Pattison, Albert
AU  - Jespersen, Jørgen
AU  - ,
TI  - INR derivation with the PT/INR Line simplified using a spreadsheet from the world wide web
AID  - 10.1136/jclinpath-2011-200068
DP  - 2011 Oct 01
TA  - Journal of Clinical Pathology
PG  - 930--932
VI  - 64
IP  - 10
4099  - http://jcp.bmj.com/content/64/10/930.short
4100  - http://jcp.bmj.com/content/64/10/930.full
SO  - J Clin Pathol2011 Oct 01; 64
AB  - Background The prothrombin time/international normalised ratio (PT/INR) Line method to derive INR, based on only five European Concerted Action on Anticoagulation (ECAA) certified plasmas, is shown to be reliable in previous ECAA studies. A simpler method not requiring linear regression calculation would be an advantage.Method After determining the local PT/INR Line, local INRs have been obtained using a readily available spreadsheet on the internet which laboratories can use without performing any additional calculations.Results Examples of INR derivation have been obtained from results at 16 centres using a range of local coagulometers with human thromboplastin international reference preparations (IRPs). The procedure does not require manual PT testing, local international sensitivity index calibration, availability of thromboplastin IRPs or local mean normal prothrombin time.Conclusions From the PT/INR Line, INR values for local PT results are easily obtained using an Excel spreadsheet from our website (http://www.anticoagulants.co.uk/) which does not require the complex linear regression analysis to derive INR.