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PubMed2002

Reliability of point-of-care prothrombin time testing in a community clinic: a randomized crossover comparison with hospital laboratory testing.

The success in achieving therapeutic international normalized ratio (INR) targets in the control of warfarin using a whole-blood point-of-care testing (POCT) monitor (CoaguChek) in a community clinic was compared with hospital laboratory coagulometer prothrombin time (PT) testing in a randomized crossover study. Forty-six patients were randomized into two groups. At each visit, capillary blood was taken for the POCT monitor and venous blood for the laboratory coagulometer. In Group 1, for 6 months, dosage was based on the CoaguChek and for the second 6 months on the coagulometer. In the second group, the order was reversed. Dosages were determined using the dawn ac computer programme. Success was assessed by the percentage of time patients were maintained within the INR targets. Agreement between laboratory and monitor INR, and patient satisfaction were also assessed. Results with the POCT monitor compared well with the hospital coagulometer. Time in INR target range between the groups was similar, with 60.9% on the POCT monitor and 59.3% with the laboratory coagulometer in Group 1 and in Group 2, respectively, 64.3% and 63.4% with no significant difference in mean INR. An INR above 4.0 gave some discrepant results. International Sensitivity Index calibrations of the two test systems indicated that the INRs were dependable. Patient questionnaires showed greater satisfaction with community POCT monitoring.

Anticoagulants↗
PubMed2003

European Concerted Action on Anticoagulation. Correction of displayed international normalized ratio on two point-of-care test whole-blood prothrombin time monitors (CoaguChek Mini and TAS PT-NC) by independent international sensitivity index calibration.

The international normalized ratio (INR) on two widely used point-of-care test (POCT) prothrombin time (PT) monitors (CoaguChek Mini and TAS PT-NC) differed considerably and also differed from the 'true' INR obtained on the same samples using a manual PT and the same species thromboplastin international reference preparation. Agreement between the displayed INR and difference from 'true' INR has been reassessed following an independent international sensitivity index (ISI) calibration of the two systems. The displayed INRs taken at seven centres were compared with 'true' INRs from the same blood donations and INRs based on the resulting ISI. The overall difference between the displayed INRs on the two monitor systems was reduced from 21.0% to 3.5%. The overall difference in mean INR of system A from the 'true' INR was reduced from 19.0% to 9.5% and of system B from 6.8% to 0.3%, but individual centre's results still showed considerable mean INR variability. Differences between overall displayed INR with the two monitor systems have been reduced by an independent multicentre calibration, and agreement with 'true' INR on the same blood samples improved. However, marked variability in mean INR at individual centres remained after ISI correction, which demonstrates the need for external quality control of individual POCT whole-blood PT monitors.

Anticoagulants↗
PubMed2003

Pregnancy-associated venous thromboembolism (VTE) in combined heterozygous factor V Leiden (FVL) and prothrombin (FII) 20210 A mutation and in heterozygous FII single gene mutation alone.

The risk of venous thromboembolism (VTE) in the absence of prophylaxis was evaluated in a retrospective study of 47 women (84 pregnancies) with combined thrombophilia [heterozygous factor V Leiden (FVL) plus prothrombin (FII) 20210A mutation (group I)] and in 82 women (193 pregnancies) with the FII alone (group II). VTE was more frequent in group I than in group II [17.8% versus 6.2%, P = 0.003, relative risk (RR) 2.9, 95% confidence interval (CI) 1.4-5.9], ante partum (7.1% and 2.1%) and post partum (11.5% and 4.2%). The risk was higher in index cases than in family members (RR 2.5, 95% CI 1.2-5.2 and RR 2.1, 95% CI 0.2-22.3 respectively) Even women who had no history of VTE before pregnancy had an increased risk (RR 2.2, 95% CI 1.0-4.8). Our results suggest that, during ante partum, prophylaxis is indicated in women with combined thrombophilia and with a VTE before pregnancy. In those without VTE before pregnancy, prophylaxis might be decided for each individual case, taking into consideration all risk factors. In women with the FII mutation alone, the low risk may not justify prophylaxis in the absence of previous VTE. In post partum, prophylaxis is indicated in all cases.

Adolescent↗
PubMed1999

Prognostic significance of anatomical resection and des-gamma-carboxy prothrombin in patients with hepatocellular carcinoma.

BACKGROUND: Portal venous tumour extension and intrahepatic metastasis result in a poor prognosis following hepatectomy for hepatocellular carcinoma (HCC). Anatomical resection is, in theory, preferable for eradicating these types of invasion. Des-gamma-carboxy prothrombin (DCP) has been reported to be associated with adverse pathological variables. This study investigated the significance of anatomical resection and DCP as predictive factors for postoperative recurrence of HCC. METHODS: A retrospective cohort study was carried out in 138 consecutive patients who underwent hepatectomy for HCC smaller than 5 cm using the Cox proportional hazards model. RESULTS: Eight factors were univariately related to poor prognosis (in decreasing order of hazard ratio): intrahepatic metastasis, multiple tumours, alpha-fetoprotein 32 ng/ml or more; DCP greater than 0.1 arbitrary units (AU), tumour-exposed surgical margin, vascular invasion, non-anatomical resection and tumour 2.5 cm or more. Three variables (DCP, vascular invasion and tumour-exposed surgical margin) were excluded by a stepwise procedure in multivariate analysis. Although DCP was not an independent prognostic factor, a model replacing intrahepatic metastasis with DCP showed similar predictive accuracy in a receiver-operating characteristic curve. CONCLUSION: Anatomical resection appeared to have a beneficial effect on recurrence-free survival after hepatectomy for HCC. DCP measurement was effective in predicting HCC recurrence and had the advantage that it can be assessed before operation.

Biomarkers↗
PubMed2001

Detection of 'antiphospholipid' antibodies: a single chromogenic assay of thrombin generation sensitively detects lupus anticoagulants, anticardiolipin antibodies, plus antibodies binding beta(2)-glycoprotein I and prothrombin.

The diagnosis of the antiphospholipid syndrome (APS) requires both a typical clinical event plus a persistently positive test in an assay for either anticardiolipin (aCL) antibodies or a lupus anticoagulant (LA). Enzyme linked immunosorbent assays (ELISA) specific for autoantibodies against beta(2)-glycoprotein I (beta(2)GPI) or prothrombin are also used, but none of the tests are adequately sensitive or specific. A chromogenic assay was developed that measures the effect of test antibody or plasma samples on in vitro thrombin formation. It is able to detect both LA and beta(2)GPI-dependent aCL antibodies and may have greater specificity for APS than currently available tests. Using this method various monoclonal antibodies (MoAbs) were examined, from mice immunized with beta(2)GPI, mice with a spontaneous animal model of APS, and from three humans with APS. Plasma and affinity purified antibodies from patients with APS and control groups were also examined. Thrombin inhibition was more sensitive to perturbation by MoAbs than a combination of tests for LA (P < 0.05) and at lower antibody concentrations (12.5 microg/ml versus 100 microg/ml). There was a significant correlation between inhibition of thrombin generation and the level of MoAb reactivity to beta(2)GPI (r = 0.90; P < 0.001) but not to CL (r = 0.06; P = 0.76). Plasma and affinity purified antibodies from patients with APS also inhibited thrombin generation, and significantly more so than patients with aPL from causes other than APS. APS patient samples showed thrombin inhibition in the presence of anti-beta(2)GPI or antiprothrombin antibodies. All MoAbs binding beta(2)GPI showed inhibition of thrombin generation, while MoAbs binding domain I of beta(2)GPI had more LA effect.

Animals↗
PubMed1999

Development of an internal restriction control in the PCR detection of the prothrombin 20210A mutation.

Detection of the presence of the 20210A/G allele in the human prothrombin gene is easily achieved by amplification using primers designed to span this region. The downstream primer creates a HindIII restriction site if the 20210A variant is present. A new forward upstream primer was designed to incorporate a naturally occurring HindIII site that, as it is present in both alleles, serves as an internal restriction control. Using this technique, the DNA of 292 unselected patients with venous thromboembolic disease was analysed. Of the 149 white patients, 4.7% were heterozygous for this mutation but none of the African Black patients were positive.

3' Untranslated Regions↗
PubMed2001

Prothrombin time inhibition detected with recombinant but not with conventional thromboplastins in two patients with high-titre IgM and moderate-titre IgA anticardiolipin antibodies.

We report two cases of high-titre IgM and moderate-titre IgA anticardiolipin antibodies (ACA) in whom prothrombin times (PT) derived using recombinant thromboplastins (rTP) were prolonged but were normal when measured with conventional thromboplastins. The anticoagulant nature of these antibodies cannot be categorized as the classical lupus type. We suggest that routine screening for the presence of antiphospholipid antibodies (APA) should be performed in patients who fall into this category.

Aged↗
PubMed2001

Reliability of delayed prothrombin time INR determinations in a central laboratory using off-site blood sampling.

A major concern of centralized anticoagulant measurements with off-site sampling is the reliability of international normalized ratio (INR) determinations on blood that may have been taken from the patient hours before the analysis. We compared INR differences in the blood of patients receiving oral anticoagulants after 24 h storage in four conditions: centrifuged at room temperature, centrifuged at 4 degrees C, uncentrifuged at room temperature and uncentrifuged at 4 degrees C. The INR of centrifuged and uncentrifuged blood left at room temperature for 24 h consistently increased by 6% and, after adjustment, there were no misclassifications in the assessment of the adequacy of anticoagulant treatment. Inconsistent changes were noted in tests of refrigerated centrifuged blood. We conclude that storage of blood at room temperature for 24 h results in a consistent prolongation of the prothrombin time, which after correction can reliably be used to adjust the dose of oral anticoagulants.

Anticoagulants↗
PubMed1997

Factor VII and activated-factor-VII content of prothrombin complex concentrates. The PCC Study Group.

BACKGROUND AND OBJECTIVES: The aim of this study was to determine the potencies of factor VII (FVII) and of activated FVII (FVIIa) in prothrombin complex concentrates (PCC). MATERIALS AND METHODS: We examined 56 lots of PCC from 5 manufacturers. Three brands were licensed preparations, and 1 product series had been involved in thromboembolic complications. FVII and FVIIa were measured using a two-stage amidolytic assay and a specific clotting assay, respectively. We also quantified FVII clotting activity by a one-stage assay reflecting a mixture of FVII zymogen and FVIIa. RESULTS: All PCC contained substantial amounts of FVII, and FVIIa could be detected in all lots. There were marked differences between manufacturers and some significant variabilities between batches. The two lots involved in thromboembolic events contained considerably more FVIIa than the PCC still licensed. The lowest FVIIa potencies were observed in an experimental product series, indicating that PCC can be produced without activation of FVII during the manufacturing process. CONCLUSION: FVIIa is present in all PCC containing FVII. High FVIIa potencies may contribute to the thrombogenic potential of these preparations, and determination of FVIIa potencies should be included in the in vitro characterization of PCC.

Blood Coagulation Tests↗
PubMed2001

Comparison of clinicopathological features of patients with hepatocellular carcinoma seropositive for alpha-fetoprotein alone and those seropositive for des-gamma-carboxy prothrombin alone.

BACKGROUND: There has been no comparative study of the clinicopathological features of HCC patients who are seropositive for alpha-fetoprotein (AFP) alone and those who are seropositive for des-gamma-carboxy prothrombin (DCP) alone. The authors, thus, performed this comparative study. METHODS: The clinicopathological features of patients with solitary hepatocellular carcinoma (HCC), who underwent a hepatectomy were compared among the four below groups according to the seropositivity of AFP and DCP: group A, seronegative for both AFP below 20 ng/mL and DCP below 40 mAU/mL; group B, seropositive for AFP above 100 ng/mL and seronegative for DCP; group C, seronegative for AFP and seropositive for DCP above 100 mAU/mL; and group D, seropositive for both AFP and DCP. RESULTS: Group B patients showed a higher incidence of HCC with an indistinct margin, and a somewhat higher incidence of small HCC less than 2 cm in greatest dimension compared with group C patients. By contrast, group C patients had a higher frequency of HCC with a distinct margin compared with that of an indistinct margin, large tumors more than 3 cm compared with that of small tumors less than 2 cm, and a somewhat higher frequency of moderately to poorly differentiated HCC compared with that of well-differentiated HCC. Our HCC cases showed advanced clinicopathological features in the order of group C, group B and group A. Groups C and D patients showed similar characteristics. CONCLUSIONS: Hepatocellular carcinoma patients who were seropositive for AFP alone demonstrated clinicopathological features of less advanced HCC compared with those who were seropositive for DCP alone.

Adult↗
PubMed1999

Maternal cardiolipin, beta 2-glycoprotein-I and prothrombin antibody expression in high-risk pregnancies with bilateral abnormal uterine artery Doppler waveforms.

OBJECTIVE: To compare the frequency of maternal serum antiphospholipid antibodies (to cardiolipin, beta 2-glycoprotein I and prothrombin) in pregnancies presenting with bilateral abnormal uterine artery Doppler waveforms. DESIGN: Retrospective analysis of stored serum. SUBJECTS: Cases comprised 47 singleton pregnancies with bilateral abnormal uterine artery Doppler waveforms at 24 weeks of gestation, followed from 20 weeks, and controls were 100 healthy pregnancies with normal uterine artery Doppler waveforms. METHODS: Ultrasound examination utilized a 5-MHz curvilinear transabdominal transducer with pulsed and color Doppler facilities. Antiphospholipid antibodies were analyzed by ELISA methodology, and reference ranges were established using the geometric mean +/- 2 SD of healthy non-pregnant adults. Human chorionic gonadotropin (hCG) levels were obtained from patient notes. RESULTS: Anticardiolipin antibodies were detected in 11 (23%) of the cases (IgG, n = 7; IgM, n = 6) compared with ten (10%) of the controls (p < 0.05). Low titer anticardiolipin IgG (range, 5.5-35.3; median, 6.3 GPL units) and anticardiolipin IgM (range, 3.4-14.7; median, 5.3 MPL units) were detected in cases. Amongst the cases, adverse perinatal outcomes were more common in the presence of raised levels of anticardiolipin antibodies. Anti-beta 2-glycoprotein I IgG was not detected in any of the cases. Antiprothrombin IgG was not detected, but antiprothrombin IgM occurred in 10.6% of cases compared with 2% of controls. CONCLUSIONS: Women with persistent bilateral abnormal uterine artery. Doppler waveforms in mid-gestation were more likely to express raised levels of anticardiolipin antibodies than healthy controls with normal uteroplacental perfusion. Anticardiolipin antibodies without anti-beta 2-glycoprotein I binding may be involved in the pathogenesis of uteroplacental ischemia in a proportion of high-risk pregnancies.

Adolescent↗
PubMed2002

Prevalence of anti-cardiolipin, anti-beta2 glycoprotein I, and anti-prothrombin antibodies in young patients with epilepsy.

PURPOSE: To measure anti-cardiolipin (aCL), anti-beta2 glycoprotein I (anti-beta2GPI), and anti-prothrombin (aPT) antibodies in young patients with epilepsy, and to correlate their presence with demographic data, clinical diagnoses, laboratory and neuroradiologic findings, and antiepileptic drugs (AEDs). METHODS: Sera from one hundred forty-two consecutive patients with epilepsy with a median age of 10 years were tested for aCL and anti-beta2GPI autoantibodies by solid-phase assays. aPT antibodies also were assayed in sera from 90 patients. Positive results were confirmed after a minimum of 6 weeks. Antinuclear antibodies (ANAs) and antibodies against extractable nuclear antigens (ENAs) also were tested. RESULTS: An overall positivity of 41 (28.8%) of 142 sera was found. Fifteen patients were positive for aCL, 25 for anti-beta2GPI, and 18 for aPT antibodies. Several patients (12%) displayed more than one specificity in their serum. Only one of these patients had a concurrent positivity for ANAs and ENAs. A predominance of younger patients was found in the antibody-positive group. All types of epilepsy were represented in the positive group. No relation between antibody positivity and AEDs was found. Diffuse ischemic lesions at computed tomography (CT)/magnetic resonance imaging (MRI) scans were present in higher percentages in patients who were antibody positive. No positive patient had a history of previous thrombosis or other features related to systemic lupus erythematosus (SLE), and no patient was born of a mother with SLE. CONCLUSIONS: Our study suggests a relation between epilepsy and aPL in young patients. A pathogenetic role for these autoantibodies cannot be excluded, and their determination might prove useful even from a therapeutic point of view.

Adolescent↗
PubMed1990

Factor IX concentrate versus prothrombin complex concentrate for the treatment of hemophilia B during surgery.

Hemophilia B patients are usually treated for the prevention and control of bleeding episodes with a plasma derivative containing the four vitamin K-dependent clotting factors (PPSB). Prothrombin complex concentrate and the French PPSB concentrate are known to be thrombogenic when used in long-term treatment of surgical patients. The present study reports two cases of thrombotic episodes following surgery in PPSB-treated hemophilia B patients. Since 1986, there has been available a factor IX (FIX) concentrate depleted of the other vitamin K-dependent clotting factors and virally inactivated by the solvent-detergent method. This preparation has been used as replacement therapy in six patients with severe hemophilia B who were to undergo orthopedic surgery. The management of the patients before and after operation was without any thrombotic complication or undesirable side effects. The present study suggests that there is a need for an FIX preparation devoid of the other vitamin K-dependent clotting factors for long-term therapy of hemophilia B patients.

Adult↗
PubMed1999

Variability of prothrombin time and activated partial thromboplastin time in the diagnosis of increased surgical bleeding.

BACKGROUND: Prothrombin time (PT) and activated partial thromboplastin time (APTT) are used to diagnose causes of increased surgical bleeding and to guide treatment of acquired coagulation factor deficiency. This study compared the sensitivity of various commercial PT and APTT tests in patients with dilutional coagulopathy. STUDY DESIGN AND METHODS: A prospective study was used to identify patients who experienced increased surgical bleeding during elective extensive (>10 spinal segments) spinal fusion and instrumentation. In patients with clinical signs of increased bleeding, blood was obtained to compare the sensitivity of various commercial PT and APTT tests. PT, PT ratio, the International Normalized Ratio (INR), APTT, and APTT ratio were compared for their sensitivity in the diagnosis of a dilutional coagulopathy. RESULTS: Sixteen patients experienced increased bleeding during surgery. Mean estimated blood volume lost exceeded 1 blood volume (1.14 +/- 0.28). PT and APTT test results varied markedly. In the most sensitive PT and APTT tests, the results were 1.5 times the mean reference range values in all but on of the patients. The least sensitive combination of tests had results that were 1.5 times the mean reference range values in only 2 of 16 patients. Variability among tests was not reduced by the use of the PT or the APTT ratio, by the use of INR, or by incorporation of a measure of PT or APTT test sensitivity to factor-deficient serum. CONCLUSION: In surgical patients with dilutional coagulopathy, diagnostic and treatment decisions could depend on which PT and APTT test was used to determine the etiology of increased bleeding. This study indicates that the relationship between increased bleeding and an increased PT and APTT may be more difficult to define than is suggested by current practice guidelines. Each laboratory must establish guidelines based on reagent and instrument sensitivity to coagulation factor dilution.

Blood Coagulation Disorders↗
PubMed2000

Frequency of factor V(Leiden) and prothrombin G20210A in placentas and their relationship with placental lesions.

The most common hereditary hypercoaguable states are factor V(Leiden) (FVL) and prothrombin mutations (PRO). FVL and PRO present with an incidence of approximately 5% in a heterogeneous population, and 45% to 63% of the thrombophilic population. The frequency of these mutations in the fetal population and their clinical importance is unknown. Fetal side thromboembolic events (FST) include congenital stroke and renal vein thromboses. In some cases, FST can be diagnosed by placental histopathology when avascular (infarcted) villi are present in a patent maternal vascular space. FST can present as placenta-fetal-vascular or fetal-visceral-vascular lesions. Causes include vascular damage from cord compression or inflammation, but most remain unclear. Potential causes of FST include FVL and PRO. We describe the incidence of FVL and PRO from a prospective group of 169 consecutive placentas and in a retrospective group of archived placentas diagnosed with placental FST. One each of FVL and PRO heterozygosity was found in the prospective set (< 1% incidence for each). Five prospective placentas were diagnosed with placental FST, for an incidence of 3%; all were wild-type for FLV and PRO. Twenty-seven of 65 archived FST cases had analyzable DNA to find 5 FVL heterozygotes (18.5%); all were wild-type for PRO. Twenty-one of 65 retrospective archived controls analyzable found 1 case of FVL heterozygosity (< 5%). We find that the frequency of FVL and PRO may be decreased in the pregnant population but increased in cases of placental FST. Because factor V Leiden heterozygosity carries an increased risk for thrombotic complications, we suggest placental diagnosis of fetal side thromboemboli warrants clinical evaluation for FVL in infant and potentially the parents.

Adolescent↗
PubMed1996

Prothrombin time in liver failure: time, ratio, activity percentage, or international normalized ratio?

Prothrombin time (PT) is a universal indicator of liver disease severity. However, variability in thromboplastin reagents leads to large interlaboratory differences in PT results. The aim of this study was to determine whether the use of the international normalized ratio (INR) or other modes of expression might achieve PT standardization in patients with liver failure. PT was measured with seven thromboplastin reagents with different sensitivities in plasmas from 27 patients with miscellaneous chronic and acute liver failure and, as a control population, 29 patients on oral anticoagulation therapy. PT was expressed in seconds, ratio, activity percentage, and INR. In patients with liver failure, only activity percentage expression eliminated variability in PT results obtained with the seven thromboplastins while INR, seconds, and ratio values remained significantly different (P < .01). In patients on oral anticoagulant therapy, only INR normalized PT results. We conclude that, in patients with liver failure, INR fails to yield a PT expression independent of the thromboplastin used and only activity percentage expression may provide a common international scale of PT reporting.

Analysis of Variance↗
PubMed1999

Effects of haemolysis, lipaemia and bilirubinaemia on prothrombin time, activated partial thromboplastin time and thrombin time in plasma samples from healthy dogs.

Interferences caused by haemolysis, lipaemia and bilirubinaemia on prothrombin time (PT), activated partial thromboplastin time (APTT) and thrombin time (TT in normal canine plasma samples were studied using commercially available reagents and a steel ball coagulometer. Haemolysis significantly interfered with APTT (P = 0.0076) and TT (P = 0.0292). Regression analysis showed that TT was significantly shortened as haemoglobin concentrations increased. Lipaemia increased as demonstrated by regression analysis. Bilirubin significantly interfered with PT (P=0.0003) and APTT (P=0.002). Although statistically significant, none of the differences found were of clinical relevance.

Animals↗
PubMed2000

Possible effects of one week vitamin K (menaquinone-4) tablets intake on glucose tolerance in healthy young male volunteers with different descarboxy prothrombin levels.

To clarify the roles of vitamin K (VK) in the pancreas, twice oral, glucose tolerance tests were examined in 12 healthy young male volunteers before and after 1 week of VK tablet intake. Blood were collected by venipucture at 0, 30 and 120 min after 75 g oral glucose loading. They then took VK tablets (90 mg/d of menaquinone-4) for 1 week, and the second glucose tolerance test was examined. The subjects were divided into three groups by serum descarboxy prothrombin (DP) levels; four of lowest DP (L-DP), middle of DP (M-DP) and highest DP (H-DP) levels. They were compared by one-factor analysis of variance and Scheffè's F (group differences) and paired t -test (the effects of 1 week of VK intake). Age, body mass index and glucose status [plasma glucose (PG) and immunoreactive insulin (IRI), hemoglobin-Alc, fructosamine] of all groups were almost the same, but the IRI of the H-DP group was higher than that of the other groups at 120 min after the glucose loading (mean+/-SEM; L; 10.6+/-0.9, M-; 17.5+/-4.2, H-; 40.4+/-6.0 microU/ml). One week of VK intake tended to decrease the plasma DP levels of all groups and significantly reduced IRI of the H-DP at 120 min by half (before; 40.4+/-6.0 vs after: 18.4+/-4.6 microU/ml). The IRI/pG ratio in areas under the curve (AUC) of H-DP from 0 to 120 min after the loading was significantly decreased by 1 week of VK tablet intake (before: 31.0+/-7.4 vs after: 20/1+/-3.8 microU/g). These results suggested that there may be some relationship between pharmacological dose of vitamin K and insulin response.

Adult↗