Effects of selected South African plant extracts on haemolysis and coagulation

The use of herbal preparations for staunching blood flow and reducing the risk of vascular thrombosis is common worldwide. In this study, aqueous and methanolic extracts of plants used to treat blood-associated complaints were investigated to determine their effects on red blood cell haemolysis and coagulation. The extent of haemolysis was determined spectrophotometrically. Prothrombin time (PT) and activated partial thromboplastin time (aPTT) as indicators of coagulation rate were determined using a coagulatometer. All of the plant extracts tested had a significant effect on coagulation time, prolonging the aPTT. Cassia petersiana had the greatest prolonging effect on PT compared to the control, phosphate buffered saline (PBS). As all of the herbal extracts tested had a delaying effect on coagulation, patients using herbal/plant therapies should be cautioned to stop their medication before surgery.The University of Pretoria, Department of Pharmacology.http://het.sagepub.co

The impact of collection tube fill volume on international normalized ratio

INTRODUCTION: Pre-analytical variability currently represents the most important source of errors that can lead to inaccurate patient results in monitoring of patients being treated with oral anticoagulant therapy. The volume of blood collected is critical for accurate coagulation results. The National Committee for Clinical Laboratory Standards (NCCLS) recommends a ratio of blood to anticoagulant volume of 9:1. However, investigators have published reports which suggest that a lower ratio may be acceptable. Unfortunately the recommendations of these reports are inconsistent. AIM: The aim of this study was to determine the impact of tube fill volume on INR values both in healthy subjects and patients receiving oral anticoagulation therapy. METHODS: INR values were obtained by processing coagulation specimens containing different volumes of whole blood. The study group included 30 patients taking oral anticoagulation therapy and 15 healthy volunteers. Respectively 2.5ml, 3 ml, 3.5 ml, 4 ml and 4.5 ml of whole blood was drawn into tubes containing a fixed volume of 3.2% (0.109M) sodium citrate. RESULTS: The INR values increased as total tube fill volumes decreased for both groups but this finding did not reach statistical significance in either group for the tube fill volumes studied. CONCLUSION: For blood specimens collected in 3.2% citrate anticoagulant, a total tube fill volume of greater than 56% yielded reliable INR resultshttp://www.smltsa.org.z