Thrombin generation test as a marker for high risk venous thrombosis pregnancies

Establishing Expectancy Values for Fibrin Monomer in Uncomplicated Pregnancy

Background  During pregnancy, a physiological increase of molecular activation markers (MAM) of hemostasis such as prothrombin fragments 1 + 2, thrombin-antithrombin complex, and D-dimers (DD) occurs. Therefore, monitoring MAM levels during pregnancy to evaluate the risk of venous thromboembolism (VTE) may be unreliable; nevertheless, DD analysis in pregnancy is widely performed. In contrast to DD, fibrin monomer (FM) levels have been reported to remain stable during pregnancy. Objectives  The main aim of this study was to define the expected range for FM levels in pregnant outpatients. In addition, we examined the impact of the individual VTE risk, as calculated by the pregnancy risk score of the Royal College of Obstetricians and Gynaecologists (RCOG), as well as that of antithrombotic treatment on FM levels. Methods  A total of 342 pregnant women seen at our hemostasis unit were included throughout 350 pregnancies in 899 samples. Results  Low-risk thrombophilia, but not the RCOG score itself, was found to influence all MAM levels, whereas antithrombotic treatment had only an impact on DD. For FM, a reference range could be calculated irrespective of the pregnancy term, in contrast to other MAMs, which fluctuated throughout pregnancy. Conclusions  Our findings suggest a stronger impact of inherited thrombophilia on hemostasis activity during pregnancy as compared with acquired or other predisposing thrombophilic risk factors. FM levels showed a marginal increase during pregnancy in contrast to other MAM and remain a potential candidate to improve the laboratory assessment of VTE risk during pregnancy. Further prospective studies in pregnant patients with suspicion of VTE are needed.

Thrombin generation assay and lupus anticoagulant synergically distinguish populations of patients with antiphospholipid antibodies

AIM

To apply thrombin generation assay (TGA) in a large cohort of antiphospholipid antibodies (aPL)-positive patients.

MATERIAL AND METHODS

108 patients were tested with TGA and lupus anticoagulant (LA) testing and divided according to their aPL profile. Briefly, 21 patients were positive for anti-phosphatidylserine (aPS)/prothrombin (PT) IgG/IgM (group1), 29 for anti-ß2-glycoprotein-I (aβ2GPI) and anti-cardiolipin (aCL) IgG/IgM (group2), 31 for aPS/PT, aβ2GPI and aCL IgG/IgM (group3), 27 for aPS/PT and/or aβ2GPI+aCL IgM at low-titres (group4). 31 healthy donors (HDs) and 24 controls treated with vitamin K antagonists (VKA) were included.

RESULTS

The most deranged TGA and LA profiles were observed in tetra-positive patients (group3) that differed significantly to the other groups, thus those with isolated, double or triple aPL-positivity. Moreover, when comparing the TGA profile of all antiphospholipid syndrome (APS) patients, aPL-carriers, HDs and VKA controls, we observed that the aPL+ patients (especially APS) showed a distinctive profile that allowed to distinguish them from the other groups with significantly higher tLag and tPeak, and lower Peak and area under the curve.When focusing on APS clinical manifestations, patients with a high-risk profile (group3) showed significant differences from those presenting low-titres aPL (group 4) regarding the number of venous events (p=0.04), recurrence of any thrombotic event (p=0.01), of arterial events (5 vs 0, p=0.02), the occurrence of TIA (p=0.04), DVT (p=0.02) and, when analysing extracriteria manifestations, of peripheral artery disease (p=0.04).

CONCLUSIONS

TGA seems a valuable approach to stratify aPL+ patients according to their risk profile. The differences among different populations of autoantibodies specificities could be considered a translational validation of the increased thrombotic risk of patients with triple or tetra aPL-positivity.

Perturbations in kinetics of the thrombin generation assay identify women at risk of preeclampsia in the first trimester and provide the rationale for a preventive approach

BACKGROUND

Activation of the coagulation system and increased thrombin generation have been implicated in the pathophysiology of preeclampsia, and this rationale supports the administration of low-molecular-weight heparin to prevent this syndrome in patients at risk. Yet, randomized trials of this prophylactic measure have yielded contradictory results. A possible explanation is that only a subset of patients with preeclampsia have excessive thrombin generation and would benefit from the administration of low-molecular-weight heparin. Therefore, the key questions are whether and when patients who subsequently develop preeclampsia present evidence of abnormal thrombin generation.

OBJECTIVE

This study aimed to determine (1) the kinetics of thrombin generation throughout gestation in women with a normal pregnancy and in those with early and late preeclampsia, and (2) the diagnostic performance of in vivo thrombin generation parameters to predict the development of preeclampsia.

STUDY DESIGN

This retrospective, nested case-control study was based on a prospective longitudinal cohort of singleton gestations. Cases comprised women who developed preeclampsia (n=49), and controls consisted of patients with a normal pregnancy (n=45). Preeclampsia was classified into early-onset (n=24) and late-onset (n=25). Longitudinal changes in the parameters of the thrombin generation assay (lag time, time to peak thrombin concentration, peak thrombin concentration, endogenous thrombin generation, and velocity index) throughout gestation were compared between the study groups, and normal pregnancy percentiles were derived from the control group. We tested whether a single parameter or a combination of parameters, derived from the kinetics of thrombin generation, could identify patients who subsequently developed preeclampsia. Time-related parameters <10th percentile were considered short, and concentration-related parameters >90th percentile were considered high.

RESULTS

(1) Patients who developed preeclampsia (early- and late-onset) had abnormal thrombin generation kinetics as early as 8 to 16 weeks of pregnancy; (2) patients with a combination of a short lag time and high peak thrombin concentration at 8 to 16 weeks of pregnancy had an odds ratio of 43.87 for the subsequent development of preeclampsia (area under the curve, 0.79; sensitivity, 56.8%; specificity, 92.7%; positive likelihood ratio, 7.76); (3) at 16 to 22 weeks of gestation, patients with a combination of a short lag time and a high velocity index had an odds ratio of 16 for the subsequent development of preeclampsia (area under the curve, 0.78; sensitivity, 62.2%; specificity, 92.5%; positive likelihood ratio, 8.29).

CONCLUSION

During early pregnancy, the thrombin generation assay can identify the subset of patients at a greater risk for the development of preeclampsia owing to accelerated and enhanced production of thrombin. This observation provides a rationale for testing the efficacy of low-molecular-weight heparin in this subset of patients. We propose that future research on the efficacy of low-molecular-weight heparin and other interventions targeting the coagulation system to prevent preeclampsia should be focused on patients with abnormal kinetics of thrombin generation.

Use of thrombomodulin-modified thrombin generation in uncomplicated pregnancy: the normal range and prothrombotic phenotype

Pregnancy is a hypercoagulable state associated with an increased risk of venous thrombosis. Thrombomodulin(TM)-modified thrombin generation is a promising laboratory method to detect the thrombotic tendency and prothrombotic phenotype. 141 women were enrolled: 30 healthy non-pregnant controls, 85 healthy pregnant women (26 in 1st trimester, 28 in 2nd trimester, 31 in 3rd trimester), and 26 patients with gestational diabetes mellitus (GDM). Thrombin generation was measured using platelet poor plasma (PPP) TM + and PPP TM- reagents. The parameters were endogenous thrombin potential (ETP), Lagtime, Peak Height, time to peak and ETP ratio(ETP(TM+)/ETP(TM-)). Protein S-depleted plasma samples with different activity were prepared and measured. Pregnancy was associated with a significant decrease of ETP in the presence of TM, compared with that found in the absence of TM. This was observed in all trimesters (1st trimester 1185.67 ± 284.95 nM*min vs.1510.39 ± 281.90 nM*min, p < .001; 2nd trimester 1458.96 ± 349.65 nM*min vs. 1929.10 ± 316.98 nM*min, p < .001; 3rd trimester 1391.60 ± 317.05 nM*min vs. 1854.88 ± 327.60 nM*min, p < .001). The ETP ratio was also markedly increased in all trimesters (0.78 ± 0.10, 0.76 ± 0.11 and 0.74 ± 0.12) compared with that of non-pregnant controls (0.51 ± 0.17, p < .001). The results of ETP ratio in protein S-depleted plasmas were 0.986, 0.943 and 0.880 with 0%, 16% and 40% of protein S activity, which indirect represented the thrombotic phenotype of PS deficiency in pregnancy. TM-modified thrombin generation serves as a useful test for hypercoagulation in pregnant women. The ETP ratio and the reference range of ETP in the presence of TM could provide the basis to predict the risk of thrombotic complications during pregnancy.

Thrombodynamics Test in Assessing the Risk of Thrombus Formation in Patients with Atrial Fibrillation Taking Direct Oral Anticoagulants

Aim. To evaluate thrombus characteristics in patients with atrial fibrillation (AF) taking different direct oral anticoagulants (DOACs) using Thrombodynamics test.Materials and methods. Thrombodynamics test was performed in 100 patients with paroxysmal and permanent forms of AF taking different DOACs, dose choice was done in accordance with the instructions for drugs use. For analysis samples of fresh citrated platelet-free plasma were taken just before regular DOACs dose intake (trough concentration). Statistical data processing was carried out using R software packages.Results. All patients had no history of thrombosis or bleeding before inclusion in this study. All parameters of Thrombodynamics test taken at residual concentration of DOACs were in general within reference values, that is in the area of normal coagulation: spatial clot growth rate (V) – 26.56 (25.0; 29.2) μm/min, the time to the start of clot growth (Tlag) – 1.05 (0.85; 1.27) min, initial spatial clot growth rate (Vi) – 44.3±7.7 μm/min, stationary spatial clot growth rate (Vst) – 26.5 (24.9; 28.4) μm/min, clot size (CS) – 999.7 (912.9; 1084.7) μm, clot density (D) – 22883.1±3199.9 arb. units. D was appeared to be higher in women [22947.7 (21477.5; 22947.7) vs men [22124.8 (19722.8; 22124.8), p=0.035] and Tlag was significantly higher in patients with chronic heart failure [1.2 (1.0; 1.2) vs 1.0 (0.8; 1.0), p=0.008]. A correlation was found between level of creatinine and Tlag parameter, glomerular filtration rate (GFR) and clot density. With an increase in the level of creatinine in the blood and a decrease in GFR, respectively, there was an increase in Tlag parameter (p-value 0.038); with an increase in GFR, clot density decrease (p-value 0.005).

Conclusion. All parameters of Thrombodynamics test on residual concentration of DOACs were within reference values that indicated optimal anticoagulant effect of all DOACs. The obtained data of normal coagulation at the residual concentration of the anticoagulant are consistent with the previously obtained data on the safety and effectiveness of DOACs using other methods. Further studies with clinical end points are needed to assess the clinical value of this method.

Potential value of the calibrated automated thrombogram in patients after a cerebral venous sinus thrombosis; an exploratory study

Background

Cerebral venous sinus thrombosis (CVST) is a relatively rare, but potentially lethal condition. In approximately 15% of the patients, the cause of CVST remains unclear. Conventional clotting tests such as prothrombin time and activated partial thromboplastin time are not sensitive enough to detect prothrombotic conditions nor mild haemostatic abnormalities. The calibrated automated thrombogram (CAT) is a physiological function test that might be able to detect minor aberrations in haemostasis. Therefore, we aimed to detect the presence of a prothrombotic state in patients who endured idiopathic CVST with the CAT assay.

Methods

Five adult patients with an idiopathic, radiologically proven CVST that had been admitted during the past 3 years were included in this study. The control group consisted of five age/gender matched healthy volunteers. Exclusion criteria were known haematological disorders, malignancy (current/past) or hormonal and anticoagulant therapy recipients. We obtained venous blood samples from all participants following cessation of anticoagulation. Using the CAT assay, we determined lag time, normalized endogenous thrombin potential (ETP), ETP reduction and normalized peak height. In addition, prothrombin concentrations were determined.

Results

We found no significant differences in lag time (4.7 min [4.5–4.9] vs 5.3 min [3.7–5.7], p = 0.691), normalized ETP (142% [124–148] vs 124% [88–138], p = 0.222), ETP reduction (29% [26–35] vs 28% [24–58], p > 0.999), and normalized peak height (155% [153–175] vs 137 [94–154], p = 0.056) between patients and their age/gender matched controls. In addition, prothrombin concentrations did not significantly differ between patients and controls (120% [105–132] vs 127% [87–139], p > 0.999).

Conclusion

Reasons for absent overt hypercoagulability within this study population may be the small patient sample, long time since the event (e.g. 3 years) and avoidance of acquired risk factors like oral contraception. Given the fact that CVST is a serious condition with a more than negligible risk of venous thrombosis event recurrence, exclusion of clinically relevant hypercoagulability remains a challenging topic to further study at the acute and later time points, particularly in patients with idiopathic CVST.

Changes in Coagulation and Fibrinolysis in Post-Cesarean Section Parturients Treated With Low Molecular Weight Heparin

BACKGROUND

Cesarean section is an independent risk factor for Venous thromboembolism (VTE). Low molecular weight heparin (LMWH) is extensively used for VTE prophylaxis after cesarean section. In this study, the effects of LMWH on coagulation and fibrinolysis after cesarean section and its clinical value were explored by studying the changes in laboratory indicators.

METHODS

Antepartum and postpartum peripheral blood of 44 pregnant women who underwent vaginal delivery and 44 pregnant women who underwent cesarean section treated per routine with LMWH thromboprophylaxis on the first day post-operatively were collected for the following tests: D-dimer; thrombotic markers such as thrombomodulin (TM), thrombin-antithrombin complex (TAT), α2-plasmin inhibitor-plasmin complex (PIC), and tissue plasminogen activator inhibitor complex (t-PAIC); thromboelastography.

RESULTS

Compared to the antepartum levels, PIC increased, TM, TAT, and t-PAIC decreased significantly in the parturients after a spontaneous vaginal delivery. Compared to the antepartum levels, parturients routinely treated with LMWH after cesarean section had higher PIC levels and lower D-dimer, TAT, and t-PAIC levels. Compared with parturients after vaginal delivery, parturients treated with LMWH after cesarean section had higher levels of TM, R, and MA, while there was no significant differences in the levels of D-dimer, TAT, PIC, t-PAIC, K, angle, LY30, and CI.

CONCLUSION

The coagulation and fibrinolytic systems in gravidas and parturients are in a high level of dynamic equilibrium. The levels of coagulation and fibrinolytic system activation were similar in parturients who were routinely treated with LMWH after cesarean section compared with parturients after a spontaneous vaginal delivery.

Assessing maternal clotting function with novel global coagulation assays: A prospective pilot study

INTRODUCTION

Women are at higher risk of venous thromboembolism (VTE) during pregnancy and the puerperium. Global coagulation assays (GCAs), including thromboelastography (TEG), thrombin generation using the calibrated automated thrombogram (CAT) and fibrin generation using the overall haemostatic potential assay (OHP), provide a more comprehensive assessment of the coagulation process than conventional coagulation assays. We aimed to evaluate the ability of these GCAs to analyse the coagulability among pregnant women of varying VTE risk profile.

METHODS

Women undergoing term elective caesarean delivery provided a single predelivery blood sample for conventional and novel coagulation testing (TEG, CAT and OHP). Data from 47 healthy nonpregnant women aged 18-45 years were used as controls.

RESULTS

Sixty women with term singleton pregnancies were included. Samples from pregnant women were hypercoagulable on most GCA parameters compared to nonpregnant controls, demonstrating increased maximum amplitude (clot strength) (71.5 vs 60.6 mm, P < .001) on whole blood TEG and increased endogenous thrombin potential (1895.22 vs 1399.33 nmol/L·min, P < .001) and overall coagulation potential (fibrin generation) (57.58 vs 36.21 units, P < .001) on platelet-poor plasma. Pregnant women with booking BMI ≥ 30 kg/m² had significantly higher maximum amplitude compared to pregnant women of normal BMI (18.5-25 kg/m² ) (73.2 vs 66.1 mm, P < .001).

CONCLUSIONS

Global coagulation assays reliably detect the physiological hypercoagulability of pregnancy. Thromboelastography in particular appears to correlate with obesity in the pregnant population. GCAs may be potential adjuncts to risk factor-based criteria to guide VTE thromboprophylaxis during pregnancy and the puerperium.

Value of TAT and PIC with D-dimer for cancer patients with metastasis

INTRODUCTION

The hypercoagulability of blood is related to the development and metastasis of cancer. High levels of D-dimer have been reported to be associated with the metastasis and poor prognoses of cancer. Here, we investigated the performance of biomarkers-TAT, PIC, TM, and tPAI·C by new method-for monitoring cancer patients with metastasis.

METHODS

A total of 197 cancer patients were enrolled. TM, TAT, PIC, and tPAI·C were detected by the chemiluminescence immunoassay.

RESULTS

Results showed that the levels of TAT and PIC were higher in the metastasis group than those in the nonmetastasis group (P < .01). In the nonmetastasis group, there were 16 patients with elevated levels of D-dimer. But, TAT and PIC in these 16 patients were all at normal level (<0.55 mg/L FEU). After dilution, D-dimer was also decreased to normal levels in these 16 patients. The ROC was used to show the performance of D-dimer, TAT, and PIC on indicating cancer with metastasis. The AUC of PIC was higher than that of D-dimer (0.825 vs. 0.770). The specificity and PPV of TAT and PIC were higher than those of D-dimer. Serial test of TAT, PIC, and D-dimer improved the specificity and positive predictive value to 90.91% [80.61%, 96.25%] and 89.29% [77.45%, 95.57%], respectively.

CONCLUSION

Combining TAT and PIC with D-dimer could be useful surveillance biomarkers for cancer with metastasis.

Compound heterozygous mutations identified in severe type I protein S deficiency impaired the secretion of protein S

AIMS

Hereditary protein S (PS) deficiency is one of the natural anticoagulant deficiencies causing thrombophilia. We herein described a young male with recurrent deep venous thrombosis, who was diagnosed as type I PS deficiency with compound heterozygous mutations of PROS1 gene. We aimed to analyse the relationship between the genotype and phenotype detection and investigate the pathological mechanisms of PROS1 mutations causing PS deficiency.

METHODS

Genetic analysis of PROS1 gene was carried out by direct sequencing. Thrombin generation potential and the inhibition function of thrombin generation by plasma PS were detected by thrombin generation test (TGT). The mRNA transcription level of mutant PS in vitro was measured by real-time PCR, while the protein level was evaluated by western blot and ELISA. Cellular distribution of the protein was further analysed by immunofluorescence.

RESULTS

Compound heterozygous mutations (PROS1 c.1551_1552delinsG, p.Thr518Argfs*39 and PROS1 c.1681C>T, p.Arg561Trp) were identified in the propositus, and the former one was a novel small indel mutation. TGT results showed impaired inhibition of thrombin generation with the addition of activated protein C in his parents with certain heterozygous mutations. In vitro expression study, p.Thr518Argfs*39 mutant produced truncated protein retained in the cytoplasm, while p.Arg561Trp mutant partially affected the secretion of PS. Both mutations are located in C-terminal sex hormone-binding globulin (SHBG)-like domain of PS.

CONCLUSIONS

Compound heterozygous mutations identified in the study have strong detrimental effect, causing severe type I PS deficiency in the propositus. SHBG-like domain of PS might play an important role in PS secretion system.

Thrombin Generation in Chinese Pregnant Women and the Effect of Insulin Use on Thrombin Generation in Patients with GDM

Pregnancy is a hypercoagulable state associated with an increased risk of venous thrombosis. Calibrated automated thrombogram (CAT) is a test to monitor the thrombin generation (TG), a laboratory marker of thrombosis risk, and increases during normal pregnancy, but it is still unclear whether TG is related to the use of insulin in pregnant women with gestational diabetes mellitus (GDM). We performed thrombin generation by CAT on 135 normal pregnant women, including 43 in first trimester, 32 in second trimester, 60 in third trimester, respectively; 68 pregnant women with GDM were also enrolled, 19 patients with GDM using insulin to control blood glucose and 49 patients control their blood glucose through diet and exercise with noninsulin treatment. The overall CAT parameters were calculated using descriptive statistics method with mean ± standard deviation. Mean endogenous thrombin potential, peak thrombin generation, and StartTail time increased significantly with the pregnancy. There was no significant difference in TG test parameters except StartTail time(P = .003) in insulin-treated GDM group when compared to those without insulin in the GDM group. The normal ranges for CAT parameters in pregnant women were determined. Thrombin generation increased significantly in first trimester and remains stable in second and third trimester. The use of insulin in patient with GDM did not affect thrombin generation test. Our study helps to establish the reference range of thrombin generation in Chinese normal pregnant population and provide more basis to predict the risk of thrombus complicating during pregnancy.

Coagulation tests and blood glucose before vaginal delivery in healthy teenage pregnant women compared with healthy adult pregnant women

The aim of this study was to compare the coagulation tests and blood glucose levels between healthy teenage pregnant patients and healthy adult pregnant patients just before vaginal deliveryIn a prospective study, 208 consecutive patients, 3rd trimester healthy pregnant women, underwent blood tests to determine their glucose levels the day before vaginal delivery. Of the 208 patients, 103 also underwent blood coagulation testing performed on the same day.The median values of the coagulation tests (APTT, prothrombin time, INR, prothrombin activity) and blood glucose were very similar in the healthy pregnant teenagers (32.6; 12.9; 1.02; 97.1; 81) compared with that in the healthy adult pregnant patients (32.45; 13.1; 1.01; 97.5; 81.2). Only the median value for fibrinogen was significantly different in healthy pregnant teenagers (348.9 mg/dL) (interquartile range 21.7) compared with that in healthy adult pregnant patients (359.1 mg/dL) (interquartile range 29.88).Significantly different median blood glucose levels also occurred in the <20; 20-29; 30-39; >40 age groups, but the glucose levels were still within normal limits.Even if there was variability between blood values from one age group to another, the median values for coagulation tests and blood glucose were very close in the healthy teenage pregnant patients compared with the median values of the healthy adult pregnant patients, just before vaginal delivery. With very few exceptions, the values for coagulation tests and blood glucose were within normal limits in all age groups of healthy pregnant patients.

The combination of Caprini risk assessment scale and thrombotic biomarkers to evaluate the risk of venous thromboembolism in critically ill patients

To evaluate the correlation between the Caprini risk assessment scale and plasma thrombosis biomarkers and estimate the validity of this method in identifying critically ill patients at high risk of venous thromboembolism (VTE).Patients with VTE who were admitted to the intensive care unit (ICU) department of West China Hospital SiChuan University from October 2016 to October 2017 were enrolled in this case-control study. We retrieved relative clinical data and laboratory test results included in the Caprini risk assessment scale to calculate the Caprini score and compared thrombosis biomarkers between various risk stratifications (low, moderate, high, and highest).A total of 151 critically ill patients were enrolled in our research, including 47 VTE and 94 non-VTE patients. The differences in Caprini score and levels of thrombosis biomarkers between the VTE and control group were significant. Thrombomodulin (TM) was positively correlated with Caprini score (R-value was .451, P < .05). Based on the receiver operating characteristic analysis, TM, tissue plasminogen activator-inhibitor complexes, D-dimer, and fibrinogen degradation products had a certain diagnostic efficiency in distinguishing VTE from others (P < .05). Using the logistic regression model, we identified that 5 risk factors, namely drinking history, major surgery (>3 hours), swollen legs (current), TM, and D-dimer, were independent factors for the occurrence of VTE in critically ill patients admitted in the ICU.Thrombosis markers were positively correlated with Caprini risk stratification. The combination of plasma markers and Caprini risk assessment scale can further increase the predictive value in critically ill patients with VTE.