Evaluation of the main coagulation tests in the presence of hemolysis in healthy subjects and patients on oral anticoagulant therapy

SummaryThis study was undertaken to appraise the application of those reagents most widely used in the UK for the detection and confirmation of lupus anticoagulant (LA) on an Amelung KC4A and a Sysmex CA-6000™ coagulometer. Five sets of dilute Russell’s viper venom time (DRVVT) reagents were assessed as well as the Textarin®-PL/ Ecarin ratio. Each DRVVT method comprised both LA detection and confirmation reagents provided by the same manufacturer. Samples were obtained from 20 normal healthy subjects, 10 LA-positive patients, 10 patients receiving oral anticoagulant therapy (OAT) who had previously been documented as LA-positive, a further 10 LA-negative patients receiving OAT and 10 LA-negative patients receiving unfractionated heparin therapy. The sensitivity and specificity of the reagents exhibited considerable variation not only between reagents, but also when the same reagent was used on the two analysers. Sensitivity ranged from 62 to 97% (all reagents both analysers), specificity went as low as 23% (Gradipore reagent on the CA-6000™) and as high as 100% (American Diagnostica Inc on both KC4A and CA-6000™). On the KC4A instrument, Unicorn Diagnostics’ lupus anticoagulant kit offered the best compromise of sensitivity and specificity (sensitivity 83% and specificity 81%). On the CA-6000™ the reagents supplied by American Diagnostica Inc exhibited optimal performance (sensitivity 90% and specificity 100%). The results indicate a need to optimise test reagents for specific analyser types, a procedure which can only be undertaken with preparations such as the proposed NIBSC reference plasmas for the detection of lupus anticoagulant.

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Outcomes of Oral Anticoagulant Therapy Managed by Telephone vs In-Office Visits in an Anticoagulation Clinic Setting

Yearbook of Pulmonary Disease ◽

10.1016/s8756-3452(08)70664-9 ◽

2008 ◽

Vol 2008 ◽

pp. 219-220 ◽

Cited By ~ 1

Author(s):

K.L. Lewis

Keyword(s):

Anticoagulant Therapy ◽

Oral Anticoagulant ◽

Oral Anticoagulant Therapy ◽

Anticoagulation Clinic ◽

Office Visits ◽

Clinic Setting

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Confusion Over the Therapeutic Range for Monitoring Oral Anticoagulant Therapy in North America

Thrombosis and Haemostasis ◽

10.1055/s-0038-1642740 ◽

1988 ◽

Vol 59 (02) ◽

pp. 129-132 ◽

Cited By ~ 24

Author(s):

J Hirsh ◽

M Levine

Keyword(s):

North America ◽

Anticoagulant Therapy ◽

Therapeutic Range ◽

Oral Anticoagulant ◽

Oral Anticoagulant Therapy

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Controlled Trial of the Sequential Use of Streptokinase and Ancrod in the Treatment of Deep Vein Thrombosis of Lower Limb

Thrombosis and Haemostasis ◽

10.1055/s-0038-1649223 ◽

1977 ◽

Vol 37 (02) ◽

pp. 222-232 ◽

Cited By ~ 12

Author(s):

D. A Tibbutt ◽

C. N Chesterman ◽

E. W Williams ◽

T Faulkner ◽

A. A Sharp

Keyword(s):

Deep Vein Thrombosis ◽

Clinical Improvement ◽

Anticoagulant Therapy ◽

Lower Limb ◽

Oral Anticoagulant ◽

Controlled Trial ◽

Oral Anticoagulant Therapy ◽

Control Group ◽

Vein Thrombosis ◽

Deep Vein

SummaryTreatment with streptokinase (‘Kabikinase’) was given to 26 patients with venographically confirmed deep vein thrombosis extending into the popliteal vein or above. Treatment was continued for 4 days and the patients were allocated randomly to oral anticoagulant therapy or a course of treatment with ancrod (‘Arvin’) for 6 days followed by oral anticoagulant therapy. The degree of thrombolysis as judged by further venographic examination at 10 days was not significantly different between the 2 groups. The majority of patients showed clinical improvement but there was no appreciable difference between the groups at 3 and 6 months. Haemorrhagic complications were a more serious problem during the period of treatment with ancrod than during the equivalent period in the control group.

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Relationship Between Total Prothrombin, Native Prothrombin and the International Normalized Ratio (INR)

Thrombosis and Haemostasis ◽

10.1055/s-0038-1656342 ◽

1992 ◽

Vol 68 (02) ◽

pp. 160-164 ◽

Cited By ~ 3

Author(s):

P J Braun ◽

K M Szewczyk

Keyword(s):

Anticoagulant Therapy ◽

Oral Anticoagulant ◽

Inverse Relationship ◽

Low Dose ◽

Oral Anticoagulant Therapy ◽

International Normalized Ratio ◽

Antigen Assay ◽

Dose Oral ◽

Anticoagulated Patients ◽

Sensitive Method

SummaryPlasma levels of total prothrombin and fully-carboxylated (native) prothrombin were compared with results of prothrombin time (PT) assays for patients undergoing oral anticoagulant therapy. Mean concentrations of total and native prothrombin in non-anticoagulated patients were 119 ± 13 µg/ml and 118 ± 22 µg/ml, respectively. In anticoagulated patients, INR values ranged as high as 9, and levels of total prothrombin and native prothrombin decreased with increasing INR to minimum values of 40 µg/ml and 5 µg/ml, respectively. Des-carboxy-prothrombin increased with INR, to a maximum of 60 µg/ml. The strongest correlation was observed between native prothrombin and the reciprocal of the INR (1/INR) (r = 0.89, slope = 122 µg/ml, n = 200). These results indicated that native prothrombin varied over a wider range and was more closely related to INR values than either total or des-carboxy-prothrombin. Levels of native prothrombin were decreased 2-fold from normal levels at INR = 2, indicating that the native prothrombin antigen assay may be a sensitive method for monitoring low-dose oral anticoagulant therapy. The inverse relationship between concentration of native prothrombin and INR may help in identification of appropriate therapeutic ranges for oral anticoagulant therapy.

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