Comparison between siliconized evacuated glass and plastic blood collection tubes for prothrombin time and activated partial thromboplastin time assay in normal patients, patients on oral anticoagulant therapy and patients with unfractioned heparin therap

Abstract Background: The quality of oral anticoagulant therapy management with coumarin derivatives requires reliable results for the prothrombin time/International Normalized Ratio (PT/INR). We assessed the effect on PT/INR of preanalytical variables, including ones related to off-site blood collection and transportation to a laboratory. Methods: Four laboratories with different combinations of blood collection systems, thromboplastin reagents, and coagulation meters participated. The simulated preanalytical variables included time between blood collection and PT/INR determinations on samples stored at room temperature, at 4–6 °C, and at 37 °C; mechanical agitation at room temperature, at 4–6 °C, and at 37 °C; time between centrifugation and PT/INR determination; and times and temperatures of centrifugation. For variables that affected results, the effect of the variable was classified as moderate when <25% of samples showed a change >10% or as large if >25% of samples showed such a change. Results: During the first 6 h after blood collection, INR changed by >10% in <25% of samples (moderate effect) when blood samples were stored at room temperature, 4–6 °C, or 37 °C with or without mechanical agitation and independent of the time of centrifugation after blood collection. With one combination of materials and preanalytical conditions, a 24-h delay at room temperature or 4–6 °C had a large effect, i.e., changes >10% in >25% of samples. In all laboratories, a 24-h delay at 37 °C or with mechanical agitation had a large effect. We observed no clinically or statistically relevant INR differences among studied centrifugation conditions (centrifugation temperature, 20 °C or no temperature control; centrifugation time, 5 or 10 min). Conclusions: We recommend a maximum of 6 h between blood collection and PT/INR determination. The impact of a 24-h delay should be investigated for each combination of materials and conditions.

Download Full-text

Newly developed modified diluted prothrombin time reagent: A multi-centre validation in patients with non-valvular atrial fibrillation under direct oral anticoagulant therapy

Thrombosis Research ◽

10.1016/j.thromres.2021.12.028 ◽

2022 ◽

Author(s):

Osamu Kumano ◽

Shinya Suzuki ◽

Masako Yamazaki ◽

Yoshimori An ◽

Masahiro Yasaka ◽

...

Keyword(s):

Atrial Fibrillation ◽

Prothrombin Time ◽

Anticoagulant Therapy ◽

Oral Anticoagulant ◽

Oral Anticoagulant Therapy ◽

Direct Oral Anticoagulant

Download Full-text

Comparison of the native prothrombin antigen and the prothrombin time for monitoring oral anticoagulant therapy

Blood ◽

10.1182/blood.v64.2.445.445 ◽

1984 ◽

Vol 64 (2) ◽

pp. 445-451 ◽

Cited By ~ 40

Author(s):

B Furie ◽

HA Liebman ◽

RA Blanchard ◽

MS Coleman ◽

SF Kruger ◽

...

Keyword(s):

Prothrombin Time ◽

Anticoagulant Therapy ◽

Oral Anticoagulant ◽

Warfarin Therapy ◽

Oral Anticoagulant Therapy ◽

Bleeding Complications ◽

Thromboembolic Complications ◽

Serum Samples ◽

Time Index ◽

Patients At Risk

Abstract We have measured the fully carboxylated (native) prothrombin antigen and the undercarboxylated (abnormal) prothrombin antigen in patients treated with sodium warfarin using specific immunoassays to evaluate a new approach for monitoring oral anticoagulant therapy. Plasma and serum samples (391) were assayed for the prothrombin time, native prothrombin antigen, and abnormal prothrombin antigen. The results were correlated with the presence of bleeding or thromboembolic complications at the time of phlebotomy. The native prothrombin antigen correlated with the occurrence of complications in 95% of samples. Of 13 samples from patients with bleeding complications, 13/13 (100%) had a native prothrombin of 12 micrograms/mL or lower. Of seven samples from patients with thromboembolic complications, 6/7 (86%) had a native prothrombin of 24 micrograms/mL or greater. By comparison, a prothrombin time index of 1.5 to 2.5, 1.5 to 2.2, 1.5 to 2.0, or 1.3 to 1.8 identified 6/20 (30%), 9/20 (45%), 11/20 (55%), or 12/20 (60%) patients at risk, respectively. Although the prothrombin time index did correlate with the presence of bleeding complications, the native prothrombin antigen correlated closely with the presence of bleeding and thromboembolic complications. According to these results, the native prothrombin antigen, maintained in a range of 12 to 24 micrograms/mL by regular adjustment of the warfarin dosage, may be associated with a reduced risk of complications due to excessive or insufficient warfarin therapy. On the basis of these preliminary data, we recommend that the native prothrombin antigen be considered to monitor warfarin therapy.

Download Full-text