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American Journal of Veterinary Research Dec 2007To evaluate a bench-top coagulation analyzer for determination of prothrombin time (PT), activated partial thromboplastin time (APTT), and fibrinogen concentration in...
OBJECTIVE
To evaluate a bench-top coagulation analyzer for determination of prothrombin time (PT), activated partial thromboplastin time (APTT), and fibrinogen concentration in healthy dogs.
ANIMALS
55 healthy adult dogs.
PROCEDURES
PT, APTT, and fibrinogen concentration were determined by use of the coagulation analyzer. Values were compared with results obtained independently by a conventional laboratory.
RESULTS
Correlations (with 95% confidence intervals) between the coagulation analyzer and conventional laboratory values were 0.760 (0.610 to 0.857), 0.700 (0.448 to 0.721), and 0.896 (0.878 to 0.918) for PT, APTT, and fibrinogen concentration, respectively. Using linear regression, comparison of data from the coagulation analyzer and the conventional laboratory provided equations relating the coagulation analyzer values with values from the conventional laboratory and suggested that APTT and fibrinogen values from the coagulation analyzer and conventional laboratory were approximately the same within expected random variation. Prothrombin time values for the coagulation analyzer were significantly offset from the PT values for the conventional laboratory but still were correlated reasonably well with the conventional laboratory values.
CONCLUSIONS AND CLINICAL RELEVANCE
By use of the mechanical method of analysis, fibrinogen concentrations obtained with a bench-top coagulation analyzer correlated well with results for a conventional laboratory, indicating that the coagulation analyzer is a reliable instrument for determination of this coagulation variable. Coagulation analyzer results for PT and APTT correlated less strongly with those for the conventional laboratory, but they would still be considered clinically reliable.
Topics: Animals; Dogs; Fibrinogen; Health; Partial Thromboplastin Time; Point-of-Care Systems; Prothrombin Time; Reference Values; Sensitivity and Specificity
PubMed: 18052739
DOI: 10.2460/ajvr.68.12.1342 -
Journal of Veterinary Internal Medicine 1995Hemostasis profiles from 101 cats presented for medical or surgical evaluation to The Ohio State University Veterinary Teaching Hospital from 1986 through 1991 were... (Review)
Review
Hemostasis profiles from 101 cats presented for medical or surgical evaluation to The Ohio State University Veterinary Teaching Hospital from 1986 through 1991 were reviewed retrospectively; 69% were abnormal. Commonly identified abnormalities included a mixed hemostatic defect compatible with disseminated intravascular coagulation, thrombocytopenia, isolated prolongation of the activated partial thromboplastin time (APTT), and prolongation of both the APTT and one-stage prothrombin time. The most common disorders associated with abnormal hemostasis profiles in this study were liver disease, neoplasia, and feline infectious peritonitis.
Topics: Animals; Blood Coagulation Disorders; Cat Diseases; Cats; Liver Diseases; Neoplasms; Partial Thromboplastin Time; Peritonitis; Prothrombin Time; Retrospective Studies; Thrombocytopenia
PubMed: 8531174
DOI: 10.1111/j.1939-1676.1995.tb01088.x -
American Journal of Veterinary Research Sep 2001To evaluate a point-of-care coagulation analyzer (PCCA) in dogs with coagulopathies and healthy dogs.
OBJECTIVE
To evaluate a point-of-care coagulation analyzer (PCCA) in dogs with coagulopathies and healthy dogs.
ANIMALS
27 healthy and 32 diseased dogs with and without evidence of bleeding.
PROCEDURE
Prothrombin time (PT), activated partial thromboplastin time (aPTT), and activated clotting time (ACT) were determined, using a PCCA and standard methods.
RESULTS
Using the PCCA, mean (+/- SD) PT of citrated whole blood (CWB) from healthy dogs was 14.5+/-1.2 seconds, whereas PT of nonanticoagulated whole blood (NAWB) was 10.4+/-0.5 seconds. Activated partial thromboplastin time using CWB was 86.4+/-6.9 seconds, whereas aPTT was 71.2+/-6.7 seconds using NAWB. Reference ranges for PT and aPTT using CWB were 12.2 to 16.8 seconds and 72.5 to 100.3 seconds, respectively. Activated clotting time in NAWB was 71+/-11.8 seconds. Agreement with standard PT and aPTT methods using citrated plasma was good (overall agreement was 93% for PT and 87.5% for aPTT in CWB). Comparing CWB by the PCCA and conventional coagulation methods using citrated plasma, sensitivity and specificity were 85.7 and 95.5% for PT and 100 and 82.9% for aPTT, respectively. Overall agreement between the PCCA using NAWB and the clinical laboratory was 73% for PT and 88% for aPTT. Using NAWB for the PCCA and citrated plasma for conventional methods, sensitivity and specificity was 85.7 and 68.4% for PT and 86.7 and 88.9% for aPTT, respectively.
CONCLUSIONS AND CLINICAL RELEVANCE
The PCCA detected intrinsic, extrinsic, and common pathway abnormalities in a similar fashion to clinical laboratory tests.
Topics: Animals; Blood Coagulation Disorders; Dog Diseases; Dogs; Partial Thromboplastin Time; Point-of-Care Systems; Predictive Value of Tests; Prothrombin Time; Reference Values; Sensitivity and Specificity; Statistics, Nonparametric; Whole Blood Coagulation Time
PubMed: 11560277
DOI: 10.2460/ajvr.2001.62.1455 -
American Journal of Veterinary Research Jun 2012To determine reference values for kaolin-activated thromboelastography in echocardiographically normal cats.
OBJECTIVE
To determine reference values for kaolin-activated thromboelastography in echocardiographically normal cats.
ANIMALS
30 healthy cats without evidence of cardiomyopathy on echocardiographic examination.
PROCEDURES
All cats underwent echocardiographic examination, the findings of which were reviewed by a board-certified cardiologist. Cats that struggled (n = 10) received mild sedation with butorphanol and midazolam IM to permit phlebotomy without interruption in jugular venous blood flow. Blood samples were collected for analysis of thromboelastography variables, PCV, total solids concentration, platelet count, activated partial thromboplastin time, prothrombin time, fibrinogen concentration, and antithrombin concentration.
RESULTS
All 4 thromboelastography variables had < 5% mean intra-assay variability. Mean values were as follows: reaction time, 4.3 minutes; clotting time, 1.6 minutes; α angle, 66.5°; and maximum amplitude, 56.4 mm. Compared with nonsedated cats, cats that required sedation had a significantly shorter clotting time and greater α angle, whereas reaction time and maximum amplitude were not significantly different.
CONCLUSIONS AND CLINICAL RELEVANCE
Kaolin-activated thromboelastography was a reliable test with unremarkable intra-assay variability in echocardiographically normal cats. Sedation may affect certain thromboelastography variables, but the effect is unlikely to be clinically important. It remains unknown whether subclinical cardiomyopathy has a significant effect on thromboelastography variables in cats.
Topics: Animals; Blood Coagulation; Cats; Echocardiography; Kaolin; Platelet Count; Prothrombin Time; Reaction Time; Reference Values; Statistics, Nonparametric; Thrombelastography
PubMed: 22620690
DOI: 10.2460/ajvr.73.6.775 -
Influence of sex on activated partial thromboplastin time (aPTT) and prothrombin time (PT) in sheep.Veterinaria Italiana Sep 2017Haemostasis is a physiological process that prevents excessive blood loss. In laboratory, the prothrombin time (PT) and the activated partial thromboplastin time (aPTT)...
Haemostasis is a physiological process that prevents excessive blood loss. In laboratory, the prothrombin time (PT) and the activated partial thromboplastin time (aPTT) are used to examine clotting systems. However, the influence of sex on PT and aPTT values is unknown. The present work aimed to determine the values for PT and aPTT in adult sheep and to evaluate their dependence on the sex of the animal. Blood samples were collected from 40 adults (1-6 years old) of mixed breed sheep (20 males and 20 females) via jugular venepuncture conducted using vacuum tubes containing 3.8% sodium citrate as an anticoagulant. PT and aPTT were determined by visual detection of clot formation. The mean PT and aPTT values for all sheep were 7.71 ± 0.87 s and 35.7 ± 3.57 s, respectively. The aPTT values showed a significant difference (P = 0.0013) between male and female samples, while the difference in PT values was not significant (P = 0.0565). Thus, the animal sex influences the function of the plasma blood-clotting system in sheep. In contrast with table 1 data, in particular, aPTT values are significantly higher in female sheep than in males.
Topics: Animals; Female; Male; Partial Thromboplastin Time; Prothrombin Time; Sex Characteristics; Sheep
PubMed: 29152708
DOI: 10.12834/VetIt.278.1021.3 -
Journal of Thrombosis and Haemostasis :... Apr 2024Calibration of prothrombin time (PT) in terms of international normalized ratio (INR) has been outlined in "Guidelines for thromboplastins and plasmas used to control...
Defining a metrologically traceable and sustainable calibration hierarchy of international normalized ratio for monitoring of vitamin K antagonist treatment in accordance with International Organization for Standardization (ISO) 17511:2020 standard: communication from the International Federation...
Calibration of prothrombin time (PT) in terms of international normalized ratio (INR) has been outlined in "Guidelines for thromboplastins and plasmas used to control oral anticoagulant therapy" (World Health Organization, 2013). The international standard ISO 17511:2020 presents requirements for manufacturers of in vitro diagnostic (IVD) medical devices (MDs) for documenting the calibration hierarchy for a measured quantity in human samples using a specified IVD MD. The objective of this article is to define an unequivocal, metrologically traceable calibration hierarchy for the INR measured in plasma as well as in whole blood samples. Calibration of PT and INR for IVD MDs according to World Health Organization guidelines is similar to that in cases where there is a reference measurement procedure that defines the measurand for value assignment as described in ISO 17511:2020. We conclude that, for PT/INR standardization, the optimal calibration hierarchy includes a primary process to prepare an international reference reagent and measurement procedure that defines the measurand by a value assignment protocol conforming to clause 5.3 of ISO 17511:2020. A panel of freshly prepared human plasma samples from healthy adult individuals and patients on vitamin K antagonists is used as a commutable secondary calibrator as described in ISO 17511:2020. A sustainable metrologically traceable calibration hierarchy for INR should be based on an international protocol for value assignment with a single primary reference thromboplastin and the harmonized manual tilt tube technique for clotting time determination. The primary international reference thromboplastin reagent should be used only for calibration of successive batches of the secondary reference thromboplastin reagent.
Topics: Adult; Humans; Prothrombin Time; International Normalized Ratio; Thromboplastin; Calibration; Chemistry, Clinical; Anticoagulants; Reference Standards; Fibrinolytic Agents; Indicators and Reagents; Communication; Vitamin K
PubMed: 38128762
DOI: 10.1016/j.jtha.2023.12.013 -
Journal of Feline Medicine and Surgery Dec 2017Objectives The objectives of this study were, first, to report the haematological parameters and coagulation times for cats with a congenital portosystemic shunt (CPSS)...
Objectives The objectives of this study were, first, to report the haematological parameters and coagulation times for cats with a congenital portosystemic shunt (CPSS) and the influence of surgical shunt attenuation on these parameters; and, second, to identify any association between prolongation in coagulation profiles and incidence of perioperative haemorrhage. Methods This was a retrospective clinical study using client-owned cats with a CPSS. Signalment, shunt type (extra- or intrahepatic), degree of shunt attenuation (complete or partial), haematological parameters, prothrombin time (PT) and activated partial thromboplastin time (aPTT) test results, and occurrence of any perioperative clinical bleeding complications were recorded for cats undergoing surgical treatment of a CPSS at the Royal Veterinary College, UK, between 1994 and 2011. Results Forty-two cats were included. Thirty-six (85.7%) had an extrahepatic CPSS and six (14.3%) had an intrahepatic CPSS. Preoperatively, mean cell volume (MCV) and mean cell haemoglobin (MCH) were below the reference interval (RI) in 32 (76.2%) and 31 (73.8%) cats, respectively. Red blood cell count and mean cell haemoglobin concentration (MCHC) were above the RI in 10 (23.8%) and eight (19.1%) cats, respectively. Postoperatively, there were significant increases in haematocrit ( P = 0.044), MCV ( P = 0.008) and MCH ( P = 0.002). Despite the significant increase in MCV postoperatively, the median MCV postoperatively was below the RI, indicating persistence of microcytosis. Preoperatively, PT was above the upper RI in 14 cats (87.5%), and aPTT was above the upper RI in 11 cats (68.8%). No cat demonstrated a perioperative clinical bleeding complication. Conclusions and relevance Cats with a CPSS are likely to present with a microcytosis, but rarely present with anaemia, leukocytosis or thrombocytopenia. Surgical attenuation of the CPSS results in a significant increase in the HCT and MCV. Coagulation profiles in cats with a CPSS are likely to be prolonged, irrespective of shunt type, but do not appear to be associated with an increased risk of clinical bleeding.
Topics: Animals; Cat Diseases; Cats; Erythrocyte Count; Female; Hypertension, Portal; Male; Partial Thromboplastin Time; Portal System; Prothrombin Time; Retrospective Studies
PubMed: 29171354
DOI: 10.1177/1098612X17693490 -
Clinical and Applied... 2012This study evaluated the prothrombin time (PT) assay for the measurement of plasma concentrations of rivaroxaban using calibrators and controls. The intra- and... (Clinical Trial)
Clinical Trial Comparative Study
This study evaluated the prothrombin time (PT) assay for the measurement of plasma concentrations of rivaroxaban using calibrators and controls. The intra- and interlaboratory precision of the measurement was investigated in a field trial involving 21 laboratories. Each laboratory was provided with rivaroxaban calibrators and control plasma samples containing different concentrations of rivaroxaban, and PT reagents. The evaluation was carried out over 2 consecutive weeks using centrally provided and local PT reagents. A calibration curve was produced each day (for inter-run precision), and day-to-day precision was evaluated by testing 3 control plasma samples. A large interlaboratory variation (in seconds) was observed with local PT reagents. The results were less variable when expressed as rivaroxaban concentrations (ng/mL) or when central PT reagent was used (STA Neoplastine CI Plus). The widely available PT assay, in conjunction with rivaroxaban calibrators, may be useful for the measurement of peak plasma levels of rivaroxaban.
Topics: Anticoagulants; Blood Preservation; Calibration; Drug Monitoring; Drug Stability; Europe; Factor VIIa; Feasibility Studies; Freeze Drying; Humans; Indicators and Reagents; Laboratory Proficiency Testing; Morpholines; North America; Osmolar Concentration; Plasma; Prothrombin Time; Reproducibility of Results; Rivaroxaban; Sensitivity and Specificity; Thiophenes
PubMed: 22387577
DOI: 10.1177/1076029611426282 -
American Journal of Hematology Aug 1997To measure the amount of tissue factor released during specimen collection and its potential effect of shortening the prothrombin time, we measured tissue factor and...
To measure the amount of tissue factor released during specimen collection and its potential effect of shortening the prothrombin time, we measured tissue factor and prothrombin time in twenty-three paired venous and capillary blood samples from anticoagulated patients and in ten paired samples from controls. We also compared venous prothrombin time determined by a plasma-based assay with venous and capillary prothrombin time determined with a whole blood assay. Venous specimens were obtained using a two-syringe technique; capillary specimens were obtained by fingerstick after wiping the first drop of blood. Plasma tissue factor was determined by an enzyme-linked immunoabsorbant assay. The patients' mean venous tissue factor (235 +/- 101 pg/ml) and capillary tissue factor (268 +/- 106 pg/ml) were higher than those of the controls (161 +/- 42 pg/ml and 187 +/- 63 pg/ml, respectively, P < 0.05). These differences disappeared after adjusting for age. Capillary tissue factor levels were higher than venous tissue factor (244 +/- 102 pg/ml vs. 213 +/- 93 pg/ml), with a mean difference of 31 pg/ml (P = 0.0001). In addition, whole blood prothrombin time was lower in the capillary than in the venous samples (17.7 +/- 5 sec vs. 18.3 +/- 5.4 sec, P = 0.004). However, there was no correlation between capillary-venous differences in tissue factor and capillary-venous differences in the whole blood prothrombin time. Whole blood capillary and venous prothrombin times highly correlated with the plasma-based venous prothrombin time (r = 0.98, P < 0.0001). These results demonstrate that obtaining blood by fingerstick does not result in a clinically significant release of tissue factor. In addition, we did not observe any interference of plasma tissue factor with the whole blood prothrombin time assay. A direct relationship between tissue factor and age was observed.
Topics: Adult; Aged; Aged, 80 and over; Anticoagulants; Antigens; Blood Specimen Collection; Capillaries; Enzyme-Linked Immunosorbent Assay; Female; Humans; Male; Middle Aged; Prothrombin Time; Thromboplastin; Veins; Warfarin
PubMed: 9257879
DOI: 10.1002/(sici)1096-8652(199707)55:4<193::aid-ajh5>3.0.co;2-n -
Clinical and Applied... Oct 2011Monitoring of direct inhibitors of thrombin (DTI) is critical for their safe and effective use as anticoagulants. We examined samples containing several concentrations... (Comparative Study)
Comparative Study
Monitoring of direct inhibitors of thrombin (DTI) is critical for their safe and effective use as anticoagulants. We examined samples containing several concentrations of argatroban or lepirudin in reconstituted standard human plasma and plasma from medical outpatients and intensive care patients. Prothrombin time (PT), activated partial thromboplastin time (aPTT), and thrombin time (TT) were determined using automated analyzers. Ecarin clotting time (ECT) was measured using a 10 IU/mL dilution of ecarin in 0.05 mol/L CaCl(2). Calibration curves were approximately linear for TT and ECT in samples containing argatroban and lepirudin, respectively. Activated partial thromboplastin curves reached a plateau at DTI concentrations ≥2 µg/mL, suggesting that the aPTT may not reliably detect overdosing. Prothrombin time increased exponentially. A broad range of clotting times was seen in patient samples with all tests suggesting that individual morbidity and therapies may strongly influence test results and may lead to underestimation of DTI doses.
Topics: Antithrombins; Arginine; Calibration; Female; Hirudins; Humans; Male; Partial Thromboplastin Time; Pipecolic Acids; Prothrombin Time; Recombinant Proteins; Sulfonamides; Thrombin Time
PubMed: 20834029
DOI: 10.1177/1076029610382651