Haematology Watch

Introduction: High haematocrit is a pre-analytical variable, and reduces plasma to anticoagulant ratio. This can lead to falsely prolonged coagulation tests.

Objectives: To determine effect of Trisodium citrate anticoagulant adjustment on Prothrombin time and Activated partial thromboplastin time in patients having high haematocrit.

Main outcome measures: Prothrombin time, Activated partial thromboplastin time.

Study design: Experimental study.

Setting: Fauji Foundation Hospital, Rawalpindi.

Subjects: Patients having high haematocrit for age and gender.

Methods: Patients having high haematocrit were included. Volume of Trisodium citrate anticoagulant was adjusted by formula ‘C = ( 1.85 × 10^-3 ) ( 100 – Hct ) ( Volume of blood )’ in ‘tube 2’, and 2.5 mL blood was taken equally in two tubes: ‘tube 1’ containing non-adjusted anticoagulant i.e. 0.25 mL and ‘tube 2’ containing adjusted anticoagulant. Both tubes were centrifuged and tested for Prothrombin time and Activated partial thromboplastin time in duplicate, and mean values were noted. Data was analyzed by Statistical Package for Social Sciences 10.

Results: Percentage difference between adjusted and non-adjusted Prothrombin time and Activated partial thromboplastin time on 50 samples was found to be 16.3% and 25.0%, respectively. P value was < 0.001.

Conclusions: In patients having high haematocrit, results of Prothrombin time and Activated partial thromboplastin Time are significantly reduced after adjusting Trisodium citrate anticoagulant.