A laboratory evaluation into the short activated partial thromboplastin time

Are shortened aPTT values always to be attributed only to preanalytical problems?

OBJECTIVES

It has been recognized that shortened activated partial thromboplastin time (aPTT) may be caused by various preanalytical conditions. As coagulation Factor VIII is included in the in vitro intrinsic coagulation cascade measured by aPTT, we hypothesized that the shortened aPTT could be a result of elevated FVIII activity. We aimed to inspect the connection of elevated FVIII with shortened aPTT, and the possible effect inflammation has on routine laboratory parameters.

METHODS

40 patients from various hospital departments with aPTT measurement below the lower limit of the reference interval (<23.0 s) were included in the study. To compare the obtained results with aPTT measurements in the non-inflammatory state, samples from 25 volunteers (laboratory personnel) were collected. White blood cell count, C-reactive protein, aPTT, and FVIII values were measured in the control group.

RESULTS

Only two samples among 40 patients with shortened aPTT (5 %) were clotted. Out of the remaining 38, 26 had FVIII activity above 150 % (upper limit of a reference interval), median value of 194 % (IQR: 143-243 %). Seven samples in the control group had shortened aPTT results (36 %). However, all coagulation samples were clot and hemolysis-free. Multiple regression identified only FVIII activity as an independent variable in predicting aPTT values (p=0.001).

CONCLUSIONS

Our results support the thesis that shortened aPTT is rarely a consequence of preanalytical problems. Elevated FVIII activity causes shortened aPTT, not only in the inflammatory state but also in individuals with concentration of inflammatory markers within reference intervals.

The Role of the von Willebrand Factor Collagen-Binding Assay (VWF:CB) in the Diagnosis and Treatment of von Willebrand Disease (VWD) and Way Beyond: A Comprehensive 36-Year History

The von Willebrand factor (VWF) collagen binding (VWF:CB) assay was first reported for use in von Willebrand diagnostics in 1986, by Brown and Bosak. Since then, the VWF:CB has continued to be used to help diagnose von Willebrand disease (VWD) (correctly) and also to help assign the correct subtype, as well as to assist in the monitoring of VWD therapy, especially desmopressin (DDAVP). However, it is important to recognize that the specific value of any VWF:CB is predicated on the use of an optimized VWF:CB, and that not all VWF:CB assays are so optimized. There are some good commercial assays available, but there are also some "not-so-good" commercial assays available, and these may continue to give the VWF:CB "a bad reputation." In addition to VWD diagnosis and management, the VWF:CB found purpose in a variety of other applications, from assessing ADAMTS13 activity, to investigation into acquired von Willebrand syndrome (especially as associated with use of mechanical circulatory support or cardiac assist devices), to assessment of VWF activity in disease states in where an excess of high-molecular-weight VWF may accumulate, and lead to increased (micro)thrombosis risk (e.g., coronavirus disease 2019, thrombotic thrombocytopenic purpura). The VWF:CB turns 37 in 2023. This review is a celebration of the utility of the VWF:CB over this nearly 40-year history.

CA125-Associated Activated Partial Thromboplastin Time and Thrombin Time Decrease in Patients with Adenomyosis

Objective

Adenomyosis patients are in a hypercoagulable state, and studies have shown that carbohydrate antigen125 (CA125) may relate to the hypercoagulability and thrombosis of patients with adenomyosis, but there is still a lack of clarity regarding the changes in CA125-related coagulation indicators. This study was to explore the changes and influencing factors of CA125-related coagulation parameters in patients with adenomyosis.

Methods

Retrospective observational study conducted on 200 patients with adenomyosis (AM group), 240 patients with uterine leiomyoma (LM group) and 81 patients with cervical intraepithelial neoplasia (CIN)-III (control group), of which the coagulation parameters were detected by clinical blood sample collection and statistical method analysis and informed consent was obtained.

Results

The level of CA125 in the AM group was significantly higher than that in the LM group and control group. However, thrombin time (TT) shortened in the AM group when compared with the LM and control group. Activated partial thromboplastin time (APTT) in the AM group was shorter than in the control group. Multivariate logistic regression analysis found that adenomyosis was associated with CA125 level (OR=323.860, 95% CI 90.424-1159.924, P<0.001), APTT (OR=1.295, 95% CI 1.050-1.598, P=0.016), TT (OR=0.642, 95% CI 0.439-0.938, P=0.022), menorrhagia (OR=7.363, 95% CI 2.544-21.315, P<0.001), dysmenorrhea (OR=22.590, 95% CI 8.185-62.347, P<0.001). Correlation analysis revealed that APTT (r= -0.207) and TT (r = -0.174) were negatively correlated with the level of CA125.

Conclusion

The shortening of CA125-related APTT and TT indicates that it is meaningful to detect coagulation parameters of patients with elevated CA125 levels early, dysmenorrhea and menorrhagia, and maybe further discover the hypercoagulability and prevent the occurrence of thrombus in adenomyosis.

Reference interval for the C-ACT activated clotting time test in healthy dogs using a water bath and manual assessment of clot formation

AIMS

To establish a reference range for the canine C-ACT activated clotting time (ACT) test using a water bath and visual clot assessment technique.

METHODS

Healthy, privately owned dogs (n = 48) were prospectively recruited to the study. Blood samples were collected via direct jugular venipuncture for complete blood count, serum biochemistry, prothrombin time (PT) and activated partial thromboplastin time (aPTT). Five animals with major abnormalities or who became agitated during phlebotomy were excluded. For the 43 remaining animals, 2 mL of blood was then collected via the cephalic vein and added directly to a C-ACT tube that was shaken vigorously before being placed in a water bath at 37°C. Tubes were visually assessed for clot formation and C-ACT was recorded in seconds when the magnet within the tube lodged in the clot.

RESULTS

Forty-three animals were eligible for inclusion. The nonparametric reference interval (capturing the central 95% of the data) was 50-80 seconds, with a 90% CI for the lower limit of 50-55 seconds and a 90% CI for the upper limit of 75-80 seconds. The C-ACT ACT test had a positive correlation with aPTT (0.42, 95% CI = 0.13-0.64). There was no evidence of a correlation between C-ACT ACT and age, weight, PT, haematocrit, white blood cell count, platelet count or total protein.

CONCLUSIONS AND CLINICAL RELEVANCE

The results of this study suggest that the normal reference interval for ACT in dogs using C-ACT tubes in a 37°C water bath is 50-80 seconds. Care should be taken extrapolating the results of this study to the general population, as the smaller study design had less control for confounders than a larger study. However, when using the described analytical methods, C-ACT tube ACT test results > 80 seconds should be considered prolonged in dogs and should prompt further investigation.

ABBREVIATIONS

ACT: Activated clotting time; aPTT: Activated partial thromboplastin time; EDTA: Ethylenediaminetetraacetic acid; Hct: Haematocrit; PT: Prothrombin time.

The Role of Platelets in the Pathogenesis and Pathophysiology of Adenomyosis

Widely viewed as an enigmatic disease, adenomyosis is a common gynecological disease with bewildering pathogenesis and pathophysiology. One defining hallmark of adenomyotic lesions is cyclic bleeding as in eutopic endometrium, yet bleeding is a quintessential trademark of tissue injury, which is invariably followed by tissue repair. Consequently, adenomyotic lesions resemble wounds. Following each bleeding episode, adenomyotic lesions undergo tissue repair, and, as such, platelets are the first responder that heralds the subsequent tissue repair. This repeated tissue injury and repair (ReTIAR) would elicit several key molecular events crucial for lesional progression, eventually leading to lesional fibrosis. Platelets interact with adenomyotic cells and actively participate in these events, promoting the lesional progression and fibrogenesis. Lesional fibrosis may also be propagated into their neighboring endometrial-myometrial interface and then to eutopic endometrium, impairing endometrial repair and causing heavy menstrual bleeding. Moreover, lesional progression may result in hyperinnervation and an enlarged uterus. In this review, the role of platelets in the pathogenesis, progression, and pathophysiology is reviewed, along with the therapeutic implication. In addition, I shall demonstrate how the notion of ReTIAR provides a much needed framework to tether to and piece together many seemingly unrelated findings and how it helps to make useful predictions.

The Effect Of Combined Oral Contraceptives And Hormone Therapy During Assisted Reproductive Technologies On The Function Of The Hemostatic System In Non-Pregnant And Pregnant Women

A review of world literature was conducted in the databases Scopus, Web of Science, MedLine, Cochrane CENTRAL, Cochrane Database of Systematic Reviews (CDSR), Database of Abstracts of Reviews of Effectiveness (DARE), EMBASE, Global Health, CyberLeninka, RSCI on the problem of the effect of combined oral contraceptives (COCs) and hormone therapy during assisted reproductive technologies on the function of the hemostatic system in non-pregnant and pregnant women. The scientific concept of this work is different in that we have summarized and analyzed information on the effect of sex hormones entering the woman’s body from the outside on individual links and the hemostatic system as a whole, determined the relationship between drug administration and thrombotic complications, optimized the sequence of diagnosis of conditions predisposing to thrombosis. The scientific novelty of this work is that we have compared the effects of COCs and hormonal changes during pregnancy on the hemostatic system and found that changes in the hemostatic system in women taking COCs are similar to those that occur during pregnancy.

Nusinersen treatment in adult patients with spinal muscular atrophy: a safety analysis of laboratory parameters

Background

Nusinersen is an intrathecally administered antisense oligonucleotide (ASO) that improves motor function in patients with spinal muscular atrophy (SMA). In addition to efficacy, the safety of a therapy is the decisive factor for the success of the treatment. For some ASOs, various organ toxicities have been described, such as thrombocytopenia, renal and liver impairment, or coagulation abnormalities. However, systematic data on laboratory parameters under treatment with nusinersen are mainly available from studies in infants and children. Therefore, our aim was to assess the safety of nusinersen therapy in adult SMA patients.

Methods

Laboratory data from 404 nusinersen injections performed in 50 adult patients with SMA type 2 and type 3 were retrospectively analyzed.

Results

The total observation period was 76.9 patient-years, and patients received up to 12 injections. Our data provides no new safety concerns. In cerebrospinal fluid (CSF), the mean white blood cell count and lactate remained stable over time. Total CSF protein increased by 2.9 mg/dL. No change in mean platelet count was observed under therapy. Only one patient showed sporadic mild thrombocytopenia. Coagulation parameters and inflammatory markers were stable. The mean creatinine level decreased by 0.09 mg/dL. Analysis of mean liver enzyme levels revealed no relevant changes during treatment.

Conclusion

Our data demonstrate a favorable safety profile of nusinersen therapy in adult SMA patients under longer-term “real-world” conditions. In particular, we found no evidence of clinically relevant platelet declines, coagulopathies, or renal or hepatic organ toxicities, which are common concerns with the use of ASOs.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-021-10569-8.

A Novel Heterozygous Variant in F2 Gene in a Chinese Patient With Coronary Thrombosis and Acute Myocardial Infarction Leads to Antithrombin Resistance

Thrombophilia refers to a group of conditions where the blood clots more easily than normal. These blood clots can cause problems such as deep vein thrombosis or pulmonary embolism. Most kinds of mutated coagulation factors II (F2) exhibit lower procoagulant activity, but in some cases, a higher coagulation rate has been observed. The underlying mechanism is that those variations can prevent F2s from being inhibited by antithrombin, leading to a contiguous activation of procoagulation, and causing recurrent thromboembolism. In this study, a patient was admitted to our hospital due to repeated chest pain for 2 days and aggravated for 4 h. A medical history investigation showed that he had three deep venous thromboses in the lower limbs and one portal vein thrombosis events during the past 10 years. The electrocardiogram showed Q wave elevation and slight ST segment elevation in lead V2, and coronary angiogram showed a total occlusion of the left anterior descending artery. Laboratory testing found that troponin I was obviously elevated. Family history also indicated that both his father (II-3) and grandfather (I-1) died from pulmonary thromboembolism. Whole-exome sequencing was performed to detect the genetic lesion of the patient, and a novel mutation (c.1621 C>T/p.R541W) of F2 was identified in the patient. This novel mutation resulted in a substitution of arginine by tryptophan, leading to antithrombin resistance (ATR). Our study is consistent with previously published papers. In conclusion, this study not only identifies a novel mutation of F2 and will contribute to the genetic diagnosis and counseling of families with thrombosis but also suggests that the site p.R541 of F2 may play a crucial role in thrombosis.

Oral contraceptive use increases risk of inflammatory and coagulatory disorders in women with Polycystic Ovarian Syndrome: An observational study

Polycystic ovarian syndrome (PCOS) is a multispectral disorder requiring lifelong management. Its pathophysiology is still being explored which makes its treatment options restrained. Present study explores impact of oral contraceptive mode of treatment on metabolic, hormonal, inflammation and coagulation profile of PCOS women. 50 subjects diagnosed with Rotterdam criteria receiving no drug treatment served as controls whereas 50 subjects receiving only OCPs (Ethinyl estradiol 0.03 mg, Levonorgestrel 0.15 mg) as a mode of treatment at least for six-months served as cases. Ferriman-Gallwey score and hormonal profile improved on OCP treatment. However, parameters like weight, Body mass index, waist-hip ratio, Oral glucose tolerance test, lipid profile, insulin, HOMA-IR, adiponectin, interleukin1β, visfatin, resistin, tissue factor, PT and APTT showed considerable derangements in OCP group. All above parameters are associated with the risk of diabetes mellitus, dyslipidemia, coronary vascular disease, cancers, hypercoagulable state, venous thromboembolism and thrombotic events. Long-term use of OCPs needs to be considered carefully for PCOS patients who are already burdened with associated risk factors. This study was conducted in a region where women do not have much access to high-end screening and diagnostic facilities that further exacerbates their clinical outcomes. Large scale, long-term studies need to be designed to further evaluate safety use of OCPs in PCOS women.

Further Evidence for Hypercoagulability in Women With Ovarian Endometriomas

Our previous studies have shown that platelets play a crucial role in the development of endometriosis, and women with endometriosis appear to be in a state of hypercoagulability. However, a recent study could only replicate part of our previous finding, casting doubts on this notion. We further investigated this question through a cross-sectional study by measuring additional coagulation factors in women with and without endometriosis. To this end, we conducted a cross-sectional study of 100 women with laparoscopically and pathologically diagnosed ovarian endometriomas (OMA) and another 100 women without endometriosis. The platelet count; platelet activation rate; maximum platelet aggregation rate; plasma levels of D-dimer, fibrinogen, fibrin degradation products (FDPs), plasma soluble P-selectin (sP-sel), and prothrombin fragment 1+2 (F1+2); prothrombin time; thrombin time (TT); and activated partial thromboplastin time were measured before surgery and 3 months after surgery, and their clinical data were recorded. These measurements were also performed in control patients. We found that, compared with controls, women with OMA had a significantly higher platelet activation rate and platelet aggregation rate, elevated plasma D-dimer, fibrinogen, FDPs, sP-sel, and F1+2 levels as well as shortened TT. Remarkably, TT was prolonged, and all the other coagulation measurements, except plasma fibrinogen level, were significantly reduced 3 months after surgical removal of endometriotic lesions. Thus, our study provides another piece of evidence that endometriosis is a hypercoagulable disease, and anticoagulation therapy may hold promises in treating endometriosis.

Haemostatic parameters, platelet activation markers, and platelet indices among regular plateletpheresis donors

OBJECTIVE

Plateletpheresis is generally a safe procedure for platelet donation. Studies on the effects of haemostatic parameters and possible association between automated plateletpheresis and hypercoagulable state are limited. Hence, this study aimed to investigate the effects of plateletpheresis on regular donors using haemostatic parameters, i.e. natural anticoagulant proteins, platelet indices, and platelet activation markers.

METHODS

A total of 139 participants (plateletpheresis donors and normal controls) were recruited and divided into two groups: Group 1 participants who underwent tests for haemostatic and platelet indices and Group 2 participants who underwent tests for platelet activation markers using CD62P and PAC-1 monoclonal antibodies.

RESULTS

A significant mild shortening of prothrombin time and platelet activation were demonstrated (by increased CD62P and PAC-1 markers) among regular plateletpheresis donors as compared to healthy controls. The current pre-donation platelet count of plateletpheresis donors was significantly lower than their mean baseline platelet count obtained before their first plateletpheresis procedure. However, no significant differences were observed for the other platelet parameters (platelet count, mean platelet volume, platelet distribution width, activated partial thromboplastin time, protein C, protein S, antithrombin, and von Willebrand Factor antigen) between plateletpheresis donors and healthy controls.

CONCLUSION

This study concludes that regular plateletpheresis is a safe procedure. A possibility of mild platelet activation among regular donors requires further confirmation. However, pre-analytical platelet and FVII activations could occur in vitro contributing to these findings.

Association of Admission Glucose Level and Improvement in Pulmonary Artery Pressure in Patients with Submassive-type Acute Pulmonary Embolism

Objective The admission glucose level is a predictor of mortality even in patients with acute pulmonary embolism (APE). However, whether or not the admission glucose level is associated with the severity of APE itself or the underlying disease of APE is unclear. Methods This study was a retrospective observational study. A pulmonary artery (PA) catheter was used to accurately evaluate the severity of APE. The percentage changes in the mean PA pressure (PAPm) upon placement and removal of the inferior vena cava filter (IVCF) were evaluated. We hypothesized that the admission glucose level was associated with the improvement in the PA pressure in patients with APE. Patients A total of consecutive 22 patients with submassive APE who underwent temporary or retrievable IVCF insertion on admission and repetitive PA catheter measurements upon placement and removal of IVCFs were enrolled. Results There was a significant positive correlation between the admission glucose levels and the percentage changes in the PAPm (r=0.543, p=0.009). A univariate linear regression analysis showed that the admission glucose level was the predictor of the percentage change in PAPm (β coefficient=0.169 per 1 mg/dL; 95% confidence interval, 0.047-0.291; p=0.009). A multivariate linear regression analysis with the forced inclusion model showed that the admission glucose level was the predictor of the percentage change in PAPm independent of diabetes mellitus, PAPm on admission, troponin positivity, and brain natriuretic peptide level (all p<0.05). Conclusion The admission glucose level was associated with the improvement in the PAPm in patients with submassive-type APE.

COAGULATION ASSESSMENT: UNDERUTILIZED DIAGNOSTIC TOOLS IN ZOO AND AQUATIC ANIMAL MEDICINE

Veterinarians specializing in nondomestic species are faced with unique challenges regarding research and diagnostic capabilities given the wild and frequently dangerous nature of their patients. Standard diagnostic techniques used in small or large animal practice are not always possible due to anatomical constraints, size, tractability, or the inherent risk of anesthesia in highly valued, rare species. Diagnostic modalities that utilize simple, relatively noninvasive techniques show promise in evaluating nondomestic species and elucidating the pathophysiology behind poorly characterized disease processes in both wild and captive populations. Coagulation profiles, which may include prothrombin time (PT), partial thromboplastin time (PTT), D-dimer concentration, platelet count, and thromboelastography (TEG) are frequently used in domestic species but often overlooked in exotic medicine due to lack of normal reference values and/or availability. Whenever possible, coagulation profiles should be utilized in the evaluation of various disease processes including neoplasia, sepsis, trauma, inflammation, toxin exposure, and envenomation. There are several reports of coagulopathies in both wild and captive species; however, few studies on coagulation profiles have been published on nondomestic species. Clinicians should consider coagulation testing as part of the diagnostic work-up in nondomestic species. A review of available coagulation diagnostic tests is provided here in addition to summarizing the pertinent coagulation disorders currently established in the literature.

The use of dielectric blood coagulometry in the evaluation of coagulability in patients with peripheral arterial disease

Background

Platelets and coagulation proteins contribute to the development of peripheral arterial disease, especially atherosclerotic disease. Several experimental studies have proven a significant correlation between hypercoagulability and atherosclerosis. We used dielectric blood coagulometry, which was initially designed to evaluate the coagulable status, to examine the coagulability of peripheral arterial disease patients, and investigated the factors that were significantly correlated with the results.

Methods

We performed dielectric blood coagulometry in 49 peripheral arterial disease patients. In addition, we recorded the patients’ demographic information, including the presence of comorbidities, hemodynamic status, and laboratory findings. To investigate coagulability, we calculated the T_max value, which indicates the time from recalcification to maximum normalized permittivity.

Results

The T_max values of diabetes mellitus patients were significantly lower than those of non-diabetic patients (1 MHz, P = 0.010; 10 MHz, 0.011). Furthermore, the T_max value was statistically correlated with the activated partial thromboplastin time (1 MHz, ρ = 0.286, P = 0.048; 10 MHz, ρ = 0.301, P = 0.037).

Conclusions

Dielectric blood coagulometry detected the hypercoagulable status in diabetes mellitus patients, and reflected their level of coagulability, which was also evaluated by the activated partial thromboplastin time.

Procoagulatory changes induced by head-up tilt test in patients with syncope: observational study

Background

Orthostatic hypercoagulability is proposed as a mechanism promoting cardiovascular and thromboembolic events after awakening and during prolonged orthostasis.

We evaluated early changes in coagulation biomarkers induced by tilt testing among patients investigated for suspected syncope, aiming to test the hypothesis that orthostatic challenge evokes procoagulatory changes to a different degree according to diagnosis.

Methods

One-hundred-and-seventy-eight consecutive patients (age, 51 ± 21 years; 46% men) were analysed. Blood samples were collected during supine rest and after 3 min of 70° head-up tilt test (HUT) for determination of fibrinogen, von Willebrand factor antigen (VWF:Ag) and activity (VWF:GP1bA), factor VIII (FVIII:C), lupus anticoagulant (LA1), functional APC-resistance, and activated prothrombin time (APTT) with and without activated protein C (C+/−). Analyses were stratified according to age, sex and diagnosis.

Results

After 3 min in the upright position, VWF:Ag (1.28 ± 0.55 vs. 1.22 ± 0.54; p < 0.001) and fibrinogen (2.84 ± 0.60 vs. 2.75 ± 0.60, p < 0.001) increased, whereas APTT/C+/− (75.1 ± 18.8 vs. 84.3 ± 19.6 s; p < 0.001, and 30.8 ± 3.7 vs. 32.1 ± 3.8 s; p < 0.001, respectively) and APC-resistance (2.42 ± 0.43 vs. 2.60 ± 0.41, p < 0.001) decreased compared with supine values. Significant changes in fibrinogen were restricted to women (p < 0.001) who also had lower LA1 during HUT (p = 0.007), indicating increased coagulability. Diagnosis vasovagal syncope was associated with less increase in VWF:Ag during HUT compared to other diagnoses (0.01 ± 0.16 vs. 0.09 ± 0.17; p = 0.004).

Conclusions

Procoagulatory changes in haemostatic plasma components are observed early during orthostasis in patients with history of syncope, irrespective of syncope aetiology. These findings may contribute to the understanding of orthostatic hypercoagulability and chronobiology of cardiovascular disease.

Factors associated with thrombotic complications in pediatric patients with vascular malformations

BACKGROUND AND OBJECTIVES

Thrombosis is an uncommon disorder in children. Patients with slowflow vascular malformations have higher risk of developing localized intravascular coagulation, which is closely related to the presence of thrombotic events. These episodes cause pain, can be recurrent and determine a clear deterioration in the quality of life. Moreover, serious complications such as pulmonary thromboembolism and eventually death have been described. The aim of the present study is to identify clinical and laboratory risk factors associated with thrombotic events in pediatric patients with vascular malformations.

METHODS

Case-Control study. Clinical records of patients who consulted the vascular anomalies study group (VASG). This group carries out interdisciplinary assessment of patients with vascular malformations. From June 2008 to December 2014, 110 patients were assessed of whom 46 patients met the inclusion criteria, with half of them presenting a thrombotic complication and the others not, these latter serving as controls. Statistical analysis included multivariate logistic regression analysis to determine major risk factors for thrombosis.

RESULTS

In the bivariate analysis we found a significant association between increased levels of Ddimer and thrombotic complications (OR 17.1 [95% CI 3.95-73.95; p<0.01]). In addition, a surface area≥10cm² (OR 6.18 [95% CI 1.59-23.99; p<0.01]) and the presence of palpable phleboliths (OR 20.17 [95% CI 2.32-165.77; p<0.01]) were associated with a significant higher risk of thrombosis. Multivariate analysis identified older age (OR 1.33; p=0.013), a surface area≥10cm² (OR 8.19; p=0.042) and palpable phleboliths (OR 85.29; p<0.01) as significant risk factors.

CONCLUSIONS

Our study suggests the existence of clinical factors associated with higher risk of thrombotic complications, such as the extent of the malformation, palpable phleboliths and increased age among children with vascular malformations.

Establishment of reference values for various coagulation tests in healthy Florida manatees (Trichechus manatus latirostris) and evaluation of coagulation in debilitated manatees during rehabilitation

OBJECTIVE

To establish reference ranges for coagulation parameters in healthy Florida manatees (Trichechus manatus latirostris) and compare results with those for debilitated manatees undergoing treatment at a rehabilitation facility.

DESIGN

Prospective study.

ANIMALS

29 healthy manatees and 45 debilitated manatees with various diseases.

PROCEDURES

Manatees considered healthy on the basis of results of physical examination, CBC, and serum biochemical analysis underwent coagulation testing including measurement of prothrombin time, partial thromboplastin time, D-dimer concentration, platelet count, and fibrinogen concentration to establish reference ranges. For comparison, a group of manatees undergoing rehabilitation was also tested, and the results were compared. Thromboelastography was also performed on some animals.

RESULTS

Values for D-dimer concentration were significantly higher in debilitated versus healthy animals. There was no significant difference for prothrombin time, partial thromboplastin time, platelet count, or fibrinogen concentration between groups. Thromboelastography was performed on 8 healthy animals.

CONCLUSIONS AND CLINICAL RELEVANCE

Reference ranges were established for various tests of coagulation that may assist clinicians during the initial evaluation and rehabilitation of Florida manatees. Future research to evaluate the effect of specific disease processes on the coagulation cascade is recommended.

Retrospective evaluation of shortened prothrombin time or activated partial thromboplastin time for the diagnosis of hypercoagulability in dogs: 25 cases (2006-2011)

OBJECTIVE

To evaluate the relationship between shortened prothrombin time (PT) or activated partial thromboplastin time (aPTT) values, clinical findings associated with hypercoagulability, suspicion of pulmonary thromboembolism (PTE), D-dimer concentrations, and thromboelastogram (TEG) indices.

DESIGN

Retrospective observational study from 2006 to 2011.

SETTING

University veterinary teaching hospital.

ANIMALS

Twenty-three dogs with TEG tracings and shortened PT or aPTT values and 23 control dogs with TEG tracings and normal PT and aPTT values.

MEASUREMENTS AND MAIN RESULTS

Parameters evaluated included signalment, coagulation testing results (PT, aPTT, D-dimer concentration), TEG measurements (R, K, α, maximal amplitude) and calculated clotting index, findings of clinical hypercoagulability (thrombosis of intravenous/intra-arterial catheters, vessel thrombosis, and suspected PTE). Dogs with shortened PT or aPTT had significantly more thrombus formation (P = 0.038), suspicion of PTE (P < 0.001), and increased D-dimer concentration (P < 0.001) compared to dogs with normal PT and aPTT values. There were no significant findings when compared to TEG values.

CONCLUSIONS

A shortened PT or aPTT in dogs may be indicative of a hypercoagulable state as evidenced by an increased incidence of thrombosis, frequency of suspected PTE, and increased circulating D-dimers. A prospective study is warranted to further evaluate the use of PT and aPTT to diagnose hypercoagulable states.

Elevated Factor VIII Levels and Shortened APTT in Recurrent Abortions

INTRODUCTION

Thrombotic disorders have been found to be associated with recurrent abortions. Several risk factors have been identified. APTT reflects the common pathway and intrinsic pathway of coagulation cascade and hence is a good marker for thrombotic work. Elevated factor VIII: C has also been identified as risk factor for recurrent miscarriage. This study aims at identifying association of elevated factor VIII levels, shortened APTT and recurrent abortions in Indian population as little has been studied about this and the literature available is also based on studies done in European population. This study also aims to find whether shortened APTT can be an independent risk as well.

MATERIALS AND METHODS

Women referred to the obstetrics department with a history of early recurrent early pregnancy loss (at least three pregnancy losses before 13 weeks of gestation) were included in this study. Exclusion criteria were elevated CRP levels, positive antiphospholipid antibodies, endocrine, immunological or anatomical cause of embryo demise. A total of 68 cases of recurrent abortion were included in this study, 68 normal pregnant females (<15 weeks of gestation) were also included as controls with no history of abortion. The age group of the cases as well as control was 20-45 years. Activated partial thromboplastin time and factor VIII assay (one stage APTT based) were done on the blood samples.

RESULTS

Increased factor VIII levels were seen in 25 cases (36.4%); 19 cases showed shortened APTT (27.3%); 12 cases showed both increased factor VIII levels as well as shortened APTT (18%). All risk factors were negative in 36 cases (52.9%). None of the controls showed elevated factor VIII levels or shortened APTT. The mean APTT values of the control subjects was 31.01 and cases were 27.01 (p=0.001). The mean factor VIII levels of case were 152.85% and control 144.953% (p=0.012).

CONCLUSION

There was significant association between recurrent abortions and elevated factor VIII :c levels and shortened APTT. Shortened APTT was also identified as an independent risk factor.

Global assays of hemostasis in the diagnostics of hypercoagulation and evaluation of thrombosis risk

Thrombosis is a deadly malfunctioning of the hemostatic system occurring in numerous conditions and states, from surgery and pregnancy to cancer, sepsis and infarction. Despite availability of antithrombotic agents and vast clinical experience justifying their use, thrombosis is still responsible for a lion’s share of mortality and morbidity in the modern world. One of the key reasons behind this is notorious insensitivity of traditional coagulation assays to hypercoagulation and their inability to evaluate thrombotic risks; specific molecular markers are more successful but suffer from numerous disadvantages. A possible solution is proposed by use of global, or integral, assays that aim to mimic and reflect the major physiological aspects of hemostasis process in vitro. Here we review the existing evidence regarding the ability of both established and novel global assays (thrombin generation, thrombelastography, thrombodynamics, flow perfusion chambers) to evaluate thrombotic risk in specific disorders. The biochemical nature of this risk and its detectability by analysis of blood state in principle are also discussed. We conclude that existing global assays have a potential to be an important tool of hypercoagulation diagnostics. However, their lack of standardization currently impedes their application: different assays and different modifications of each assay vary in their sensitivity and specificity for each specific pathology. In addition, it remains to be seen how their sensitivity to hypercoagulation (even when they can reliably detect groups with different risk of thrombosis) can be used for clinical decisions: the risk difference between such groups is statistically significant, but not large.

A genetic association study of activated partial thromboplastin time in European Americans and African Americans: the ARIC Study

Reduced activated partial thromboplastin time (aPTT) is a risk marker for incident and recurrent venous thromboembolism (VTE). Genetic factors influencing aPTT are not well understood, especially in populations of non-European ancestry. The present study aimed to identify aPTT-related gene variants in both European Americans (EAs) and African Americans (AAs). We conducted a genetic association study for aPTT in 9719 EAs and 2799 AAs from the Atherosclerosis Risk in Communities (ARIC) study. Using the Candidate Gene Association Resource (CARe) consortium candidate gene array, the analyses were based on ∼50 000 SNPs in ∼2000 candidate genes. In EAs, the analyses identified a new independent association for aPTT in F5 (rs2239852, P-value = 1.9 × 10(-8)), which clusters with a coding variant rs6030 (P-value = 7.8 × 10(-7)). The remaining significant signals were located on F5, HRG, KNG1, F11, F12 and ABO and have been previously reported in EA populations. In AAs, significant signals were identified in KNG1, HRG, F12, ABO and VWF, with the leading variants in KNG1, HRG and F12 being the same as in the EAs; the significant variant in VWF (rs2229446, P-value = 1.2 × 10(-6)) was specific to the AA sample (minor allele frequency = 19% in AAs and 0.2% in EAs) and has not been previously reported. This is the first study to report aPTT-related genetic variants in AAs. Our findings in AAs demonstrate transferability of previously reported associations with KNG1, HRG and F12 in EAs. We also identified new associations at F5 in EAs and VWF in AAs that have not been previously reported for aPTT.

Association of activated partial thromboplastin time and fibrinogen level in patients with type II diabetes mellitus

Background

Patients with diabetes mellitus have a high risk of atherothrombotic events. Diabetes contributes for initiation and progression of microvascular and macrovascular complications. Shortened activated partial thromboplastin time (aPTT) values may reflect hypercoaguable state, which is associated with increased thrombotic risk and adverse cardiovascular events. Increased level of fibrinogen is common in type II diabetes. The present study was conducted to study the aPTT and fibrinogen levels in diabetics in a tertiary care Teaching Hospital of Nepal.

Methods

Observational study was performed at out-patients visiting Pathology Department at Tribhuvan University Teaching Hospital from August 5 to September 7, 2012. Research protocol was approved by Institutional Review Board at Tribhuvan University Institute of Medicine. Altogether 90 people who came to the hospital during study period and who met inclusion criteria were selected, out of which 72 were diabetics and 18 were normal controls. Diabetic cases were identified via verbal interview with patients themselves and review of laboratory findings and diagnosis performed by their physicians. Diabetics with a diabetic history of more than one year and stabilized with antidiabetic medicines such as insulin, metformin, glibenclamide, and gliclazide and diabetics with controlled diabetes as revealed by HbA_1c in the range 6.2-7% were taken for the study purpose. Data were analyzed with chi square test and Fischer’s exact test (when each cell frequency was less than 5) using Statistical Package for Social Sciences 17.

Results

Maximum (53; 73.6%) diabetics and all non-diabetics had aPTT in the range 26–40 seconds. Maximum (51; 70.8%) patients had fibrinogen beyond 351 whereas all non-diabetics had fibrinogen in the range 151–350. Mean aPTT values of the diabetic patients and non-diabetic persons were 29.88 ± 4.89 seconds and 32.44 ± 2.25 seconds respectively. Mean fibrinogen values of the diabetic patients and non-diabetic persons were 388.57 ± 60.90 mg/dL and 320.89 ± 10.20 mg/dL respectively. Test data identified in results were statistically significant for aPTT (p value 0.000) and fibrinogen (p value 0.000) between the diabetics and non-diabetics.

Conclusions

Diabetics have an increased level of fibrinogen and relatively shortened aPTT as compared to the non-diabetic patients.

Low intraindividual variability of activated partial thromboplastin time revealed in a population of 10,487 control individuals

The activated partial thromboplastin time (aPTT) is a routine coagulation test that reflects the activities of multiple coagulation proteins. Given the known genetic elements underlying the different coagulation factor activities, a low intraindividual variability is expected in aPTT values, but has not been demonstrated in a large population. In this regard, we evaluated the intraindividual variability of aPTT by analyzing serial aPTTs from a large population. The study population consisted of control individuals who had three or more consecutive aPTT values at at least 6-month intervals at a single institution. The coefficient of variation of serial aPTT values was determined in each control individual, and the mean value of the coefficient of variations in the control population was calculated. The aPTT values from a total of 10,487 individuals [mean age 57 years (range 21-93 years); male-to-female ratio 1 : 0.9] were included. The mean value of the coefficient of variation of aPTTs in those individuals was 3.75%, which indicates a very low intraindividual variability. This is the first study to demonstrate a low intraindividual variability of aPTT in a large population. The result supports the previous notion that aPTT is a genetically determined parameter and has potential clinical implications.

Revisiting cerebral thromboangiitis obliterans

We describe a 56-year-old patient with progressive cognitive decline in the context of heavy tobacco use and migraine, and imaging evidence of an occlusive terminal cerebral vasculopathy. The results of brain biopsy recapitulated the pathological features described by Lindenberg and Spatz in their classic 1939 treatise on cerebral thromboangiitis obliterans, or cerebral Buerger's disease. Although the condition is associated with heavy smoking, the identification of a hypercoagulable state in our patient suggests a multifactorial pathogenesis. The diagnosis of cerebral thromboangiitis obliterans in life is facilitated by modern neuroimaging and should prompt immediate cessation of smoking and a search for an underlying prothrombotic tendency.

The new oral anticoagulants and the future of haemostasis laboratory testing

The tests currently employed within most haemostasis laboratories to monitor anticoagulant therapy largely comprise the prothrombin time (PT)/ International Normalised Ratio (INR) and the activated partial thromboplastin time (APTT). These are respectively used to monitor Vitamin K antagonists (VKAs) such as warfarin, and unfractionated heparin. Additional tests that laboratories may also employ for assessing or monitoring unfractionated heparin include thrombin time (TT) and the anti-Xa assay, which can also be used to monitor low molecular weight heparin. Several new anti-thrombotic agents have recently emerged, or are in the final process of clinical evaluation. These novel drugs that include Dabigatran etexilate and Rivaroxaban would not theoretically require monitoring; however, testing is useful in specific situations. The tests currently used to monitor VKAs and heparin are typically either too sensitive or too insensitive to the new drugs to be used as 'typically performed in laboratories', and may thus require some methodological adjustments to increase or decrease their sensitivity. Alternately, different tests may be better employed in these assessments. Whatever the case, laboratories may soon be performing a reduced or possibly increased number of tests, the same kind of tests but perhaps differently, or conceivably different assay panels. Specific laboratory guidance on the choice of the appropriate test to be ordered according to the drug being administered, as well as on appropriate interpretation of test results, will also be necessary. The current report reviews the current state of play and provides a glimpse to the possible future of the coagulation laboratory.

Coagulation update: what's new in hemostasis testing?

The current report provides a personal perspective summarising some interesting recent developments in hemostasis, as well as providing a brief glimpse into some possible imminent changes to come. We briefly review routine coagulation tests, and what changes may take place related to the new emerging anticoagulants. We also briefly review the old and new global tests of hemostasis, including thrombin generation and thromboelastography. Also briefly discussed within the diagnostics of bleeding and thrombotic disorders are the role of microparticles, the rise and fall of thrombophilia testing, the 'disappearance' of fibrinolysis pathway tests, and the absence of tests related to the endothelium, in part reflecting upon Virchow's triad.

Shortened activated partial thromboplastin time: causes and management

Throughout the long history of the hemostasis laboratory, and as an evaluation of the coagulation cascade, the results of the activated partial thromboplastin time (APTT) have primarily been considered as an index of loss-of-function and rarely as an index of gain-of-function. Nevertheless, there are now several clinical and technical reasons that no longer allow us to simply ignore or overlook shortened APTTs in laboratory practice. It has long been suspected that the leading cause of shortened APTTs are related to preanalytical problems, in which case it would be inappropriate for a laboratory to issue such a test result, which would expectedly not adequately mirror the patient's true condition. Should such artifactual results be reliably ruled out, that is by confirming short APTT values on subsequent samples, it would then be worth considering to troubleshoot potential causes, inasmuch as this phenomenon may reflect a variety of clinically meaningful conditions, including an increased risk of thromboembolic events, cancer, myocardial infarction, thyroid disorders, diabetes, and pregnancy. Although there are no univocal data supporting the origin of this singular phenomenon as yet, we strongly encourage the utility of postanalytical laboratory guidance, including a relevant short accompanying comment in the laboratory report linked to the APTT test result, for example, noting 'Short APTT-potentially reflective of in-vitro activation of blood coagulation due to difficult collection. If the value is systematically confirmed in subsequent samples, please contact the laboratory to help assess the cause'.

Diabetes mellitus is associated with shortened activated partial thromboplastin time and increased fibrinogen values

OBJECTIVE

This study was designed to examine the relationship between shortened activated partial thromboplastin time (APTT) and increased fibrinogen values with diabetes mellitus.

METHODS

APTT, prothrombin time (PT), fibrinogen, fasting plasma glucose (FPG) and glycosylated hemoglobin A1c (HbA1c) levels were measured in 1,300 patients. Patients were divided into three groups according to their HbA1c and FPG levels.

RESULTS

When participants were grouped according to their HbA1c levels, we found significantly shorter APTT values (26.9±5.6 s) and increased fibrinogen levels (3.1, 1.9-6.3 g/L) in the diabetes group when compared with the other two groups. When participants were grouped according to their FPG levels, we found significantly shorter APTT values (26.9±6.2 s) and increased fibrinogen levels (3.1, 1.8-6.2 g/L) in the diabetes group when compared with the euglycemic group.

CONCLUSIONS

Shorter APTT and increased fibrinogen levels might be useful hemostatic markers in patients with diabetes and in patients at high risk for diabetes.