scholarly journals Isocitrate as Calcium Ion Activity Buffer in Coagulation Assays

1999 ◽  
Vol 45 (8) ◽  
pp. 1176-1180 ◽  
Author(s):  
Mats RÅnby ◽  
Tony Gojceta ◽  
Kerstin Gustafsson ◽  
Kenny M Hansson ◽  
Tomas L Lindahl
Keyword(s):  
Partial Thromboplastin Time ◽  
Calcium Ion ◽  
Activated Partial Thromboplastin Time ◽  
Plasma Samples ◽  
Healthy Individuals ◽  
Physiological Concentration ◽  
Diagnostic Efficacy ◽  
Coagulation Assays ◽  
Coagulation Tests ◽  
Ion Activity

Abstract Background: Ca2+ activity close to the physiological concentration of 1.3 mmol/L is essential in blood coagulation. Is this also true for the performance of global diagnostic coagulation assays? We searched for compounds that would buffer Ca2+ activity at ∼1.3 mmol/L without disturbing coagulation reactions and investigated whether such Ca2+ buffering improves diagnostic efficacy in global diagnostic coagulation tests. Methods: Buffering was investigated by mixing CaCl2 and 11 candidate compounds and determining Ca2+ activity. The best candidates were added to mixtures of plasma and thromboplastin to detect interference with coagulation reactions. The best of these candidates, isocitrate, was used to modify an activated partial thromboplastin time (APTT), buffering final Ca2+ activity to ∼1.3 mmol/L. Plasma samples from 22 healthy individuals and 120 patients were analyzed with original and modified APTT to determine whether diagnostic efficacy was improved. Results: Two suitable Ca2+ buffers, citrate and isocitrate, were found. Isocitrate was preferred as being less coagulation inhibitory, a better Ca2+ buffer, and possibly a better anticoagulant. The isocitrate-modified APTT showed a final Ca2+ activity of 1.60 ± 0.07 mmol/L, compared with 2.73 ± 0.20 mmol/L for the original APTT. The means and SDs for the healthy individuals were determined for both procedures, and the values were used to express patient deviation from normality (difference from mean divided by SD). The deviation was greater for the modified APTT; 4.3 ± 5.7, compared with 3.6 ± 5.0 (P <0.005) for the original APTT. Conclusions: Isocitrate can be used to buffer Ca2+ activity at physiological concentrations and can serve as an anticoagulant. APTT with isocitrate-buffered Ca2+ activity shows signs of improved diagnostic efficacy.

Interferences in coagulation tests – evaluation of the 570-nm method on the Dade Behring BCS analyser

2005 ◽  
Vol 43 (2) ◽  
Author(s):  
Ralf Junker ◽  
Margit Käse ◽  
Helmut Schulte ◽  
Ruth Bäumer ◽  
Claus Langer ◽  
...  
Keyword(s):  
Optical Properties ◽  
Prothrombin Time ◽  
Partial Thromboplastin Time ◽  
Activated Partial Thromboplastin Time ◽  
Plasma Samples ◽  
Comparison Methods ◽  
Coagulation Tests ◽  
Elisa Technique ◽  
Roche Diagnostics ◽  
D Dimer

AbstractThe Dade Behring BCS is a coagulation analyser with optical reaction detection (standard 405nm). The present study was conducted to evaluate measurement at 570nm for analyses in interfering plasma samples. Prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen and D-dimer in normal (n=50), lipaemic (n=60), icteric (n=113), and haemolytic (n=58) samples were measured at 405 and 570nm. As they are unaffected by the optical properties of the sample, the mechanical STAcompact analyser (Roche Diagnostics) and an ELISA technique were defined as the “comparison” methods. The percentage of valid PT results using the 570-nm method varied from 54% (lipaemic samples) to 97% (haemolytic samples). Valid aPTT measurements were found in 67% (lipaemic samples) up to 93% (icteric samples) of samples. Fibrinogen measurement revealed valid results in 58% (lipaemic samples) to 100% (haemolytic samples) of samples. The number of valid D-dimer results varied from 28% (lipaemic material) up to 100% (haemolytic material). Significant inter-method differences were found: aPTT in lipaemic (BCS 405 vs. 570nm) and icteric samples (STAcompact vs. BCS 405 and 570nm); fibrinogen in lipaemic (BCS 405 vs. 570nm), icteric (BCS 405 vs. 570nm; STAcompact vs. BCS 570nm) and haemolytic samples (STAcompact vs. BCS 405 and 570nm). Differences between the BCS 570-nm and the STAcompact methods were in most cases low and less pronounced than between the BCS 570- and 405-nm methods, making the BCS 570-nm method an alternative to measurement at 405nm. Limitations have to be taken into account regarding lipaemic plasma.

Can RoTEM®analysis be applied for haemostatic monitoring in paediatric congenital heart surgery?

2011 ◽  
Vol 21 (6) ◽  
pp. 684-691 ◽  
Author(s):  
Jo Bønding Andreasen ◽  
Anne-Mette Hvas ◽  
Kirsten Christiansen ◽  
Hanne Berg Ravn
Keyword(s):  
Cardiac Surgery ◽  
Platelet Count ◽  
Prothrombin Time ◽  
Partial Thromboplastin Time ◽  
Congenital Heart ◽  
Heart Surgery ◽  
Congenital Heart Surgery ◽  
Activated Partial Thromboplastin Time ◽  
Clotting Time ◽  
Coagulation Tests

AbstractBackgroundSuccessful management of bleeding disorders after congenital heart surgery requires detection of specific coagulation disturbances. Whole-blood rotation thromboelastometry (RoTEM®) provides continuous qualitative haemostatic profiles, and the technique has shown promising results in adult cardiac surgery.SettingTo compare the performance of RoTEM®with that of conventional coagulation tests in children, we conducted a descriptive study in children undergoing congenital cardiac surgery. For that purpose, 60 children were enrolled and had blood samples taken before, immediately after, and 1 day after surgery. Conventional coagulation tests included: activated partial thromboplastin time, prothrombin time, fibrinogen, fibrin D-dimer, thrombin clotting time, factor XIII, and platelet count.ResultsPost-surgical haemostatic impairment was present to some degree in all children, as seen by pronounced changes in activated partial thromboplastin time, prothrombin time, thrombin clotting time, and platelet count, as well as RoTEM®analysis. RoTEM®showed marked changes in clotting time – prolonged by 7–18% – clot formation time – prolonged by 46–71% – maximum clot firmness – reduced by 10–19%, and maximum velocity – reduced by 29–39%. Comparison of the two techniques showed that conventional coagulation tests and RoTEM®performed equally well with regard to negative predictive values for excessive post-operative drain production – more than 20 millilitres per kilogram per 24 hours after surgery – with an area under the curve of approximately 0.65.ConclusionRoTEM®can detect haemostatic impairments in children undergoing cardiac surgery and the method should be considered as a supplement in the perioperative care of the children where targeted transfusion therapy is necessary to avoid volume overload.

scholarly journals Effect of storage time on prothrombin time and activated partial thromboplastin time: study at a tertiary care center in Kashmir valley

2018 ◽  
Vol 4 (7) ◽  
pp. 182
Author(s):  
Sajad Geelani ◽  
Gul Sajad Wani ◽  
Subuh Parvez Khan ◽  
Syed Mudasir Qadri ◽  
Javid Rasool ◽  
...  
Keyword(s):  
Prothrombin Time ◽  
Partial Thromboplastin Time ◽  
Storage Temperature ◽  
Care Center ◽  
Tertiary Care ◽  
Activated Partial Thromboplastin Time ◽  
Time Interval ◽  
Tertiary Care Center ◽  
Kashmir Valley ◽  
Coagulation Tests

<p class="abstract"><strong>Background:</strong> Prothrombin time (PT) and activated partial thromboplastin time (APTT) are tests of haemostasis commonly employed in the evaluation of coagulopathies. Storage temperature and time interval between sample collection and testing can have a significant effect on results of coagulation tests. The aims of the study were investigate whether storage temperature and time influence the results of routine coagulation tests and whether any changes caused by delayed analysis results in a clinically relevant difference, as well as to establish our own acceptable storage temperature and time guidelines.</p><p class="abstract"><strong>Methods:</strong> This study was conducted at Department of Clinical Haematology, in a tertiary care center in Kashmir valley. This study included 50 cases. Individuals with chronic liver diseases or cardiovascular disorders, subjects on anticoagulant therapy were excluded. 25 samples were observed at room temperature (RT) and 25 samples at 2-8°C. PT and APTT was measured at 0, 2, 4, 8, 16 and 24 hours both at RT and 2-8°C. Findings at 0 hr were compared to findings at 2,4, 8,16 and 24 hours in both the groups.  </p><p class="abstract"><strong>Results:</strong> In case of PT, reliable results were obtained up to 24 hrs either kept at RT or at 2 to 8°C and for APTT reliable results were obtained up to 4 hours kept at RT or at 2 to 8°C as there was no significant change during this period.</p><p class="abstract"><strong>Conclusions:</strong> Coagulation test should be performed as soon as possible with PT being performed before 24 hours and APTT before 4 hours of collection of sample irrespective of whether the sample has been preserved at RT or in refrigerator.</p>

Properties of Optical Data from Activated Partial Thromboplastin Time and Prothrombin Time Assays

1997 ◽  
Vol 78 (03) ◽  
pp. 1079-1087 ◽  
Author(s):  
Paul J Braun ◽  
Thomas B Givens ◽  
Andrew G Stead ◽  
Lisa R Beck ◽  
Sheila A Gooch ◽  
...  
Keyword(s):  
Prothrombin Time ◽  
Partial Thromboplastin Time ◽  
Optical Transmittance ◽  
Coagulation Factors ◽  
Activated Partial Thromboplastin Time ◽  
Optical Data ◽  
Change Rate ◽  
Coagulation Assays ◽  
Signal Change ◽  
Coagulation Proteins

SummaryChanges in characteristics of optical transmittance data from coagulation assays were examined as a function of concentration of coagulation proteins or anticoagulants. Transmittance data were collected for activated partial thromboplastin time (APTT) and prothrombin time (PT) assays from: 1) plasmas prepared by mixing normal plasmas with deficient plasmas to give varying levels of coagulation proteins; 2) plasmas containing added heparin; and 3) 200 specimen plasmas that were also assayed for fibrinogen, coagulation factors, and other components. Optical profiles were characterized using a set of parameters describing onset and completion of coagulation, magnitude of signal change, rate of coagulation and other properties. Results indicated that parameters other than those typically reported for APTT and PT are associated with individual deficiencies, but that diagnosis of specimen status on the basis of optical data is complex. These results suggest possibilities for expanded interpretation of PT/APTT optical data for clinical or research applications.

The Control Of Heparin Administration By The Activated Partial Thromboplastin Time(APTT)

1981 ◽  
Author(s):  
Jean M Thomson
Keyword(s):  
Quality Control ◽  
Partial Thromboplastin Time ◽  
Activated Partial Thromboplastin Time ◽  
Reference Laboratory ◽  
Plasma Samples ◽  
Heparin Administration ◽  
National Quality ◽  
Fresh Plasma ◽  
Low Levels ◽  
The Uk

The UK National Quality Control Trials have previously shown that the various APTT methods differ in their ability to detect low levels of heparin (Poller et al 1980). UK and US proficiency surveys have also shown lack of linearity of some APTT methods over a range of heparin concentrations. A further, recent collaborative exercise, using lyophilised plasma from a heparinised donor, has confirmed that most of the commonly-used commercial reagents have a higher threshhold of sensitivity to heparin than the reference reagent provided by the National (UK) Reference Laboratory. Additional studies on fresh plasma samples obtained from heparinised patients, have demonstrated considerable variations in the detection of heparin by widely-used commercial APTT techniques.

Control of Heparin Treatment with three Different Methods. Behaviour of Antithrombin III

1979 ◽  
Author(s):  
H. Bounameaux ◽  
G.A. Marbet ◽  
H. Airenne ◽  
E. Grossmann ◽  
B. Stanojevic ◽  
...  
Keyword(s):  
Correlation Coefficient ◽  
Partial Thromboplastin Time ◽  
Antithrombin Iii ◽  
Heparin Therapy ◽  
Activated Partial Thromboplastin Time ◽  
Thrombin Time ◽  
Plasma Samples ◽  
Heparin Concentration ◽  
The Mean ◽  
Antithrombin Iii Activity

In 63 plasma samples from patients under heparin we determined the heparin concentration using the chromogenic substrats S-2222 (COATEST Heparin). Thrombin time (TT), activated partial thromboplastin time (APTT), antithrombin III activity (ATIIIact) and concentration (ATIIIimm) were also measured. A good correlation was found between heparin concentration and TT (r= .850, p< .001), heparin concentration and APTT (r =669, p < .001) while the correlation coefficient r between TT and APLT was .896 (p< .001).We found a statilttically significant reduction of ATIIIact with increasing APTT (p < .05. The ATIIIact and ATIIIimm values were also lower (p < .001) in the overanticoaculated group (n=ll) than in the group with insufficient heparinisation (0.18). The mean (±SO) heparin concentration in 12 plasmas with both TT and APTT in the therapeutic range was .54 (±.15) USP-U/al, very similar to that of 13 plasma (.68 ± .46 U/al) insufficiently heparinised accordirig to the APTT. However, the TT recognised then as correctly anticoagulated. Regarding these findings and our good experience without complication by monitoring heparin therapy with TT we assume that TT is more accurate than APTT for this aim.

Interference of the new oral anticoagulant dabigatran with frequently used coagulation tests

2012 ◽  
Vol 50 (9) ◽  
Author(s):  
Walter-Michael Halbmayer ◽  
Guenter Weigel ◽  
Peter Quehenberger ◽  
Josef Tomasits ◽  
Alexander C. Haushofer ◽  
...  
Keyword(s):  
Oral Anticoagulant ◽  
Dabigatran Etexilate ◽  
The Elderly ◽  
Multicenter Trial ◽  
Plasma Samples ◽  
Activity Assay ◽  
Coagulation Assays ◽  
New Oral Anticoagulant ◽  
Coagulation Tests

AbstractDabigatran etexilate is a new oral anticoagulant for the therapy and prophylaxis of venous thromboembolism and stroke prevention in patients with atrial fibrillation. To investigate the extent of interactions of this new anticoagulant with frequently used coagulation assays, we completed a multicenter in vitro trial with Conformité Européenne(CE)-labeled dabigatran-spiked plasma samples.Lyophilized plasma samples with dabigatran concentrations ranging from 0.00 to 0.48 μg/mL were sent to the coagulation laboratories of six major Austrian hospitals for evaluation. Coagulation assays were performed under routine conditions using standard reagents and analyzer.Dabigatran led to a dose-dependent prolongation of the clotting times in coagulometric tests and influenced the majority of the parameters measured. Statistically significant interference could be observed with the prothrombin time (PT), activated partial thromboplastin time (aPTT) and PT/aPTT-based assays (extrinsic/intrinsic factors, APC-resistance test) as well as lupus anticoagulant testing. Even non-clotting tests, such as the colorimetric factor XIII activity assay and to a minor extent the amidolytic antithrombin activity assay (via factor IIa) were affected.This multicenter trial confirms and also adds to existing data, demonstrating that laboratories should expect to observe strong interferences of coagulation tests with increasing concentrations of dabigatran. This finding might become particularly important in the elderly and in patients with renal impairment as well as patients whose blood is drawn at peak levels of dabigatran.

scholarly journals Activated Partial Thromboplastin Time as a Screening Test of Minor or Moderate Coagulation Factor Deficiencies for Canine Plasma: Sensitivity of Different Commercial Reagents

2000 ◽  
Vol 12 (5) ◽  
pp. 433-437 ◽  
Author(s):  
Reinhard Mischke
Keyword(s):  
Partial Thromboplastin Time ◽  
Screening Test ◽  
Reference Range ◽  
Standardized Test ◽  
Coagulation Factor ◽  
Activated Partial Thromboplastin Time ◽  
Plasma Samples ◽  
Test Protocol ◽  
Different Types ◽  
Canine Plasma

To determine the sensitivity for detection of coagulation factor deficiencies by commercial reagents for canine plasma, 5 commercial activated partial thromboplastin time (APTT) reagents with different types of contact activator and phospholipid of various origin were examined. Thirty canine plasma samples with minor or moderate deficiencies of coagualition factors that influence the APTT were examined. Significant differences were found for the sensitivity of various reagents, but no correlation was found with the type of contact activator. Following the test instructions provided by the manufacturers, the number of APTT results that were prolonged beyond the reference range varied between 20 and 30 (sensitivity = 0.67–1.00); the number of corresponding results using a standardized test protocol varied between 19 and 28 (sensitivity: 0.63–0.93). The most sensitive reagent contained kaolin as a contact activator and a human placental thromboplastin. The results of this study indicate that the APTT test optimized for human plasma is also a sensitive screening test of the intrinsic system of canine plasma, provided that a suitable reagent is used.

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