Coagulation Research Articles

Bromadiolone may cause severe acute kidney injury through severe disorder of coagulation: a case report

BackgroundBromadiolone is a wide-use long-acting anticoagulant rodenticide known to cause severe coagulation dysfunction. At present, there have been no detailed reports of acute kidney injury (AKI) resulting from bromadiolone poisoning.Case presentationA 27-year-old woman was admitted to the hospital due to severe coagulopathy and severe AKI. Coagulation test revealed a prothrombin time exceeding 120 s and an international normalized ratio (INR) greater than 10. Further examination for coagulation factors showed significantly reduced level of factors II, VII, IX and X, indicating a vitamin K deficiency. The AKI was non-oliguric and characterized by gross dysmorphic hematuria. Following the onset of the disease, the patient’s serum creatinine rose from 0.86 to 6.96 mg/dL. Suspecting anticoagulant rodenticide poisoning, plasma bromadiolone was identified at a concentration of 117 ng/mL via gas chromatography/mass spectrometry. All other potential causes of AKI were excluded, except for the presence of a horseshoe kidney. The patient’s kidney function fully recovered after the coagulopathy was corrected with high doses of vitamin K and plasma transfusion. At a follow-up 160 days post-discharge, the coagulation function had normalized, and the serum creatinine had returned to 0.51 mg/dL.ConclusionBromadiolone can induce AKI through a severe and prolonged coagulation disorder. Kidney function can be restored within days following treatment with high-dose vitamin K1.

Coagulation factor XII contributes to renin activation, heart failure progression, and mortality.

Symptomatic heart failure (sHF) with cardiac dysfunction, edema, and mortality are driven by overactivation of the renin-angiotensin-aldosterone system (RAAS). Renin is widely recognized as a key initiator of RAAS function, yet the mechanisms that activate renin remain a mystery. We discovered that activated coagulation factor XII generates active renin in the circulation and is directly linked to pathological activation of the systemic RAAS, development of sHF, and increased mortality. These findings suggest a new paradigm for therapeutically modulating the RAAS in sHF and other pathological conditions.

Unfavorably altered fibrin clot phenotype in women following postpartum hemorrhage of unknown cause: effect of lower coagulation factors.

Background Increased clot permeability and susceptibility to lysis have been reported in women with heavy menstrual bleeding. We hypothesized that similarly altered fibrin clot properties in women with postpartum hemorrhage (PPH) of unknown cause. Objective To determine fibrin clot properties and their determinants in women after PPH of unknown cause. Methods We studied 52 consecutive women, aged 35 years (27-40), after at least 3 months since PPH of unknown cause and 52 matched controls for age, weight, and fibrinogen. Coagulation factors (F), antithrombin, thrombin generation, along with a comprehensive plasma fibrin clot analysis including fibrin polymerization, clot permeability (Ks), and fibrinolysis efficiency were determined. Results Women with PPH showed reduced activity of FII (-10.3%), FV (-6.6%), FIX (-6.5%), FX (-7.2%), and FXI (-5.7%) compared to the controls, though all values were within ranges (all p<0.05). There were no intergroup differences in fibrinogen, FVIII, FXIII, and thrombin generation. The PPH group formed with a delay looser plasma fibrin network (Ks; +16.3%, p=0.008) with lower maximum absorbance and shorter clot lysis time (CLT; -13.5%, p=0.001) compared to the controls. On multivariable logistic regression, PPH was independently associated with higher C-reactive protein (per 1 mg/L, OR=1.70, 95% CI 1.09-2.68), lower FII (per 1%, OR=0.93, 95% CI 0.89-0.98), lower FV (per 1%, OR=0.93, 95% CI 0.89-0.97), and shorter CLT (per 1 min, OR=0.94, 95% CI 0.90-0.98). Conclusion Prohemorrhagic fibrin clot properties, with lower, though normal coagulation factors characterize women with PPH of unknown cause, which suggests novel mechanisms contributing to this type of bleeding.

Hepatic Proteomic Changes Associated with Liver Injury Caused by Alcohol Consumption in Fpr2-/- Mice.

Alcohol-associated liver disease (ALD) is a prevalent medical problem with limited effective treatment strategies. Although many biological processes contributing to ALD have been elucidated, a complete understanding of the underlying mechanisms is still lacking. The current study employed a proteomic approach to identify hepatic changes resulting from ethanol (EtOH) consumption and the genetic ablation of the formyl peptide receptor 2 (FPR2), a G-protein coupled receptor known to regulate multiple signaling pathways and biological processes, in a mouse model of ALD. Since previous research from our team demonstrated a notable reduction in hepatic FPR2 protein levels in patients with alcohol-associated hepatitis (AH), the proteomic changes in the livers of Fpr2-/- EtOH mice were compared to those observed in patients with AH in order to identify common hepatic proteomic alterations. Several pathways linked to exacerbated ALD in Fpr2-/- EtOH mice, as well as hepatic protein changes resembling those found in patients suffering from AH, were identified. These alterations included decreased levels of coagulation factors F2 and F9, as well as reduced hepatic levels of glutamate-cysteine ligase catalytic subunit (GCLC) and total glutathione in Fpr2-/- EtOH compared to WT EtOH mice. In conclusion, the data suggest that FPR2 may play a regulatory role in hepatic blood coagulation and the antioxidant system, both in a pre-clinical model of ALD and in human AH, however further experiments are required to validate these findings.

Factor XII signaling via uPAR-integrin β1 axis promotes tubular senescence in diabetic kidney disease

Coagulation factor XII (FXII) conveys various functions as an active protease that promotes thrombosis and inflammation, and as a zymogen via surface receptors like urokinase-type plasminogen activator receptor (uPAR). While plasma levels of FXII are increased in diabetes mellitus and diabetic kidney disease (DKD), a pathogenic role of FXII in DKD remains unknown. Here we show that FXII is locally expressed in kidney tubular cells and that urinary FXII correlates with kidney dysfunction in DKD patients. F12-deficient mice (F12-/-) are protected from hyperglycemia-induced kidney injury. Mechanistically, FXII interacts with uPAR on tubular cells promoting integrin β1-dependent signaling. This signaling axis induces oxidative stress, persistent DNA damage and senescence. Blocking uPAR or integrin β1 ameliorates FXII-induced tubular cell injury. Our findings demonstrate that FXII-uPAR-integrin β1 signaling on tubular cells drives senescence. These findings imply previously undescribed diagnostic and therapeutic approaches to detect or treat DKD and possibly other senescence-associated diseases.

Assessment of joint health in patients receiving prophylaxis for haemophilia A: a cross-sectional survey in five European countries

ObjectivesTo evaluate joint health, pain and health-related quality of life (HRQoL) in patients with moderate/severe haemophilia A in Europe.DesignMultinational, cross-sectional survey, with retrospective data collection. Data were taken from the...

Synergistic Procoagulant Mechanism and Application of Kaolin-Zeolite Composite Hemostat for Effective Hemorrhage Control.

Achieving timely and effective hemorrhage control is imperative for the survival of individuals with severe bleeding. Hemostatic materials, by enhancing the natural cell-based coagulation response, are essential tools in modern and military medical practice for controlling bleeding, especially in emergency and surgical settings. Here, we report a new type of composite hemostatic material with two different aluminosilicate-based components, kaolin and zeolite, which synergistically work together in different stages of the coagulation cascade reactions. Kaolin can effectively activate the clotting factor FXII in the early stage, and zeolite can accumulate and assemble FXa and FVa on its surface and thereafter lead to the formation of highly active thrombin in the later stage. The synergistic action mechanism between kaolin and zeolite significantly boosts the levels of FXIIa and FXa, and it also greatly enhances plateau thrombin activity. For practical application, a kaolin-modified zeolite gauze is fabricated, and it demonstrates excellent hemostatic effectiveness. Compared to the combat gauze currently used in front-line treatment, it reduces blood loss by 75% and shortens hemostasis time by 33% in a rabbit femoral artery injury model. In addition, this kaolin-zeolite gauze has no heat release problem and a nearly zero particle shedding rate, which greatly decreases the safety risk compared to current commercial inorganic-based hemostatic gauzes.

WITHDRAWN: Proteogenomic analyses identify coagulation factor XI as a thromboinflammatory mediator of long COVID.

The authors have withdrawn their manuscript due to analytical errors invalidating the main study findings. The authors of this work discovered the errors after submitting the initial version of the preprint. Therefore, the authors do not wish this work to be cited as reference for the project. If you have any questions, please contact the corresponding author.

A Cross-Sectional Study of the A1 Phenotype in the Colombian Caribbean: A Shadow Behind Pulmonary Embolism.

Venous thromboembolic disease (VTE) is an episodic condition of multifactorial origin, commonly manifesting as deep vein thrombosis (DVT) and pulmonaryembolism (PE). VTE is a major cause of morbidity and mortality. As an acute condition, it has the potential for recurrence and is associated with major consequences; this disease poses significant challenges to the healthcare system. VTE is a widespread concern in developed and developing countries; therefore, it is not limited to specific regions or populations. To evaluate the risk factors associated with unprovoked PE in patients in a hospital center in Sincelejo, Colombia. This is an observational, analytical cross-sectional study utilizing retrospective data. From 2010 to 2023, we reviewed 126 medical records of patients who experienced their first unprovoked VTE events and met the inclusion criteria. We performed data analysis using R software version 3.5.1. Of the patients, 36.5% (n = 46) were women; 63.5% (n = 80) were men, with a mean age of 62.22 years (SD = 10.62). About 53% of women presented with PE, compared to 47% of men. The coagulation factor VIII acted as a PE risk factor (p = 0.098). The best model to predict PE development obtained an Akaikeinformationcriterion (AIC) of 176.67, indicating that the A1 positive phenotype is the risk factor with the highest prediction for PE occurrence. High levels of coagulation factor VIII and an A1-positive phenotype are risk factors that may increase PE development. These findings suggest the need for preventive strategies in this risk setting to reduce the incidence and recurrence of PE.

The impact of severe nephrotic syndrome on thyroid function, nutrition and coagulation.

Nephrotic syndrome (NS) is characterized by urinary loss of proteins, including hormones and their carrier proteins, potentially resulting in endocrine disorders. This study aimed to assess thyroid dysfunction frequency and potential implications in NS. In this case-control study, patients with severe NS (serum albumin ≤2.5g/dl) and controls without proteinuria were evaluated for thyroid, haemostatic and nutritional parameters, including body composition. A total of 42 nephrotic and 40 non-proteinuric patients were enrolled. The NS group showed higher thyroid-stimulating hormone and lower free hormones, corresponding to a higher frequency of both euthyroid sick syndrome {ESS; 36% versus 5%; odds ratio [OR] 10.6 [95% confidence interval (CI) 2.2-50.0]} and hypothyroidism [31% versus 5%; OR 8.5 (95% CI 1.8-40.7)] compared with the control group. Levothyroxine supplementation was required for 11 NS patients (26% of the NS group). In addition, compared with control individuals, NS patients exhibited lower lean tissue mass and a trend towards hypercoagulability, which was evidenced by higher levels of most coagulation factors and fibrinolysis inhibitors, and reduced endogenous anticoagulants activities. Furthermore, NS patients with ESS presented with a 10.4kg (95% CI -18.68 to -2.12) lower lean tissue mass. Those with hypothyroidism had significantly reduced activity of coagulation factor X [by -30% (95% CI -47 to -13)] and protein S [by -27% (95% CI -41 to -13)] compared with euthyroid NS individuals. Thyroid dysfunction is common in severe NS, often necessitating levothyroxine supplementation, which supports routine thyroid workup. A potential link between thyroid, nutritional and coagulation disorders in NS requires further investigation.

RNAi targeting LMAN1-MCFD2 complex promotes anticoagulation in mice.

Combined deficiency of coagulation factor V (FV) and factor VIII (FVIII) is a rare bleeding disease caused by variants in either lectin mannose binding 1 (LMAN1) or multiple coagulation factor deficiency 2 (MCFD2) gene. Reducing the level of FVIII by inhibiting the LMAN1-MCFD2 complex may become a new anticoagulant approach. We aimed to find a new therapeutic option for anticoagulation by RNA interference (RNAi) targeting LMAN1 and MCFD2. siRNA sequences with cross-homology between mice and humans were designed based on LMAN1 or MCFD2 transcripts in NCBI and were screened with the Dual-Luciferase reporter assay. The optimal siRNAs were chemically modified and conjugated with three N-acetylgalactosamine molecules (GalNAc-siRNA), promoting their targeted delivery to the liver. The expression of LMAN1 and MCFD2 in cell lines or mice was examined by RT-qPCR and western blotting. For the mice administered with siRNA, we assessed their coagulation function by measuring APTT and the activity of FVIII factor. After administration, siRNAs GalNAc-LMAN1 and GalNAc-MCFD2 demonstrated effective and persistent LMAN1 and MCFD2 inhibition. 7 days after injection of 3mg/kg GalNAc-LMAN1, the LMAN1 mRNA levels reduced to 19.97% ± 3.78%. MCFD2 mRNA levels reduced to 32.22% ± 13.14% with injection of 3mg/kg GalNAc-MCFD2. After repeated administration, APTT was prolonged and the FVIII activity was remarkably decreased. The tail bleeding test of mice showed that the amount of bleeding in the treated group did not significantly increase compared with the control group. Our study confirms that therapy with RNAi targeting LMAN1-MCFD2 complex is effective and can be considered a viable option for anticoagulation drugs. However, the benefits and potential risk of bleeding in thrombophilic mice model needs to be evaluated.

Clot waveform analysis to differentiate mild, moderate, and severe hemophilia A

Background Clot waveform analysis can be used to evaluate clot formation profiles. This waveform can be obtained from activated partial thromboplastin time (APTT) assays without additional reagents and shows different patterns in hemophilia patients with coagulation factor VIII (F VIII) deficiency or abnormality. Objective To determine the clot wave pattern and its process in clot formation phases (pre-coagulation, coagulation, and post-coagulation) in normal and hemophilia A subjects, analyze for possible correlations between clot wave parameters and F VIII activity, and obtain the pattern of coagulation curves in hemophilia subjects as a step to assess clot waveform analysis as a possible screening tool for hemophilia. Methods In this cross-sectional study, we performed clot wave analysis in 145 adult and pediatric subjects with hemophilia to obtain the clot wave pattern in this condition. Clot wave analysis was also done in 160 subjects with normal hemostasis to obtain reference clot wave parameters. Results In this study, the starting point of coagulation phase in normal subjects was between 30-40 seconds, with a shorter pre-coagulation phase and steeper slope. Hemophilia patients had a longer pre-coagulation phase and flatter slope, especially in severe hemophilia A patients, who had longer and more variable coagulation starting points (P&lt;0.001). The absolute values of maximum coagulation velocity (Min1), maximum coagulation acceleration (Min2), and maximum coagulation deceleration (Max2) of hemophilia A patients were also lower than those of normal hemostasis patients, with lower absolute value seen in severe than in mild-moderate hemophilia A patients. A moderate correlation was found between Min1, Min2, and Max2 with F VIII activity (P&lt;0.001). Conclusion Clot wave analysis may be considered as a method for screening hemophilia patients to distinguish mild-moderate and severe hemophilia A patients in health facilities that lack the ability to perform F VIII assays.

Thrombin Generation Is Associated With Extracellular Vesicle and Leukocyte Lipid Membranes in Atherosclerotic Cardiovascular Disease.

Clotting, leading to thrombosis, requires interactions of coagulation factors with the membrane aminophospholipids (aPLs) phosphatidylserine and phosphatidylethanolamine. Atherosclerotic cardiovascular disease (ASCVD) is associated with elevated thrombotic risk, which is not fully preventable using current therapies. Currently, the contribution of aPL to thrombotic risk in ASCVD is not known. Here, the aPL composition of circulating membranes in ASCVD of varying severity will be characterized along with the contribution of external facing aPL to plasma thrombin generation in patient samples. Thrombin generation was measured using a purified factor assay on platelet, leukocyte, and extracellular vesicles (EVs) from patients with acute coronary syndrome (n=24), stable coronary artery disease (n=18), and positive risk factor (n=23) and compared with healthy controls (n=24). aPL composition of resting/activated platelet and leukocytes and EV membranes was determined using lipidomics. External facing aPLs were detected on EVs, platelets, and leukocytes, elevating significantly following cell activation. Thrombin generation was higher on the surface of EVs from patients with acute coronary syndrome than healthy controls, along with increased circulating EV counts. Thrombin generation correlated significantly with externalized EV phosphatidylserine, plasma EV counts, and total EV membrane surface area. In contrast, aPL levels and thrombin generation from leukocytes and platelets were not impacted by disease, although circulating leukocyte counts were higher in patients. The aPL membrane of EV supports an elevated level of thrombin generation in patient plasma in ASCVD. Leukocytes may also play a role although the platelet membrane did not seem to contribute. Targeting EV formation/clearance and developing strategies to prevent the aPL surface of EV interacting with coagulation factors represents a novel antithrombotic target in ASCVD.

Coagulation factor X promotes resistance to androgen-deprivation therapy in prostate cancer

Although hypercoagulability is commonly associated with malignancies, whether coagulation factors directly affect tumor cell proliferation remains unclear. Herein, by performing single-cell RNA sequencing (scRNA-seq) of the prostate tumor microenvironment (TME) of mouse models of castration-resistant prostate cancer (CRPC), we report that immunosuppressive neutrophils (PMN-MDSCs) are a key extra-hepatic source of coagulation factor X (FX). FX activation within the TME enhances androgen-independent tumor growth by activating the protease-activated receptor 2 (PAR2) and the phosphorylation of ERK1/2 in tumor cells. Genetic and pharmacological inhibition of factor Xa (FXa) antagonizes the oncogenic activity of PMN-MDSCs, reduces tumor progression, and synergizes with enzalutamide therapy. Intriguingly, F10high PMN-MDSCs express the surface marker CD84 and CD84 ligation enhances F10 expression. Elevated levels of FX, CD84, and PAR2 in prostate tumors associate with worse survival in CRPC patients. This study provides evidence that FXa directly promotes cancer and highlights additional targets for PMN-MDSCs for cancer therapies.

Mathematical modeling identifies clotting factor combinations that modify thrombin generation in normal and factor VIII-, IX-, or XI-deficient blood

BackgroundIn healthy individuals, plasma levels of clotting proteins naturally vary within a range of 50% to 150% of their mean values. We do not know how these variations modify thrombin generation. ObjectivesTo assess the impact of protein level variations on simulated thrombin generation in normal and factor (F)VIII-, FIX-, or FXI-deficient blood. MethodsWe used a mathematical model of flow-mediated coagulation to simulate thrombin generation with all possible combinations of clotting protein variations within the normal range and for various tissue factor levels. We selected, analyzed, and ranked combinations that enhanced thrombin generation compared with baseline. ResultsProtein variations most strongly affected thrombin generation at intermediate tissue factor levels. Low tissue factor levels prevented coagulation initiation, while high tissue factor levels always triggered thrombin generation. At intermediate levels, we identified protein variations that substantially modified thrombin generation. Low-normal FV shortened lag times and increased thrombin generation, whereas high-normal FV lengthened lag times and reduced thrombin generation. With severe FVIII and FIX deficiencies, low-normal tissue factor pathway inhibitor α and antithrombin amplified the effect of low-normal FV. For moderate FVIII and FIX deficiencies, high-normal tissue factor pathway inhibitor α and antithrombin enhanced the impact of high-normal FV in reducing thrombin production. In normal and FXI-deficient blood, high-normal FVIII and FIX significantly boosted thrombin generation. ConclusionOur mathematical model predicted how variations in clotting protein levels, within the normal range, could contribute to the variability of bleeding phenotypes observed with clotting factor deficiencies. Our study generated experimentally testable hypotheses that could aid in developing new therapies toward normal hemostasis.

Genetic engineering of megakaryocytes from blood progenitor cells using messenger RNA lipid nanoparticles

BackgroundPlatelets are an essential component of hemorrhage control and management, and engineering platelets to express therapeutic proteins could expand their use as a cell therapy. Genetically engineered platelets can be achieved by modifying the platelet precursor cells, megakaryocytes (MKs). Current strategies include transfecting MK progenitors ex vivo with viral vectors harboring lineage-driven transgenes and inducing the production of in vitro modified platelets. The use of viruses, however, poses challenges in clinical implementation, and no methods currently exist to genetically modify MKs with nonviral techniques. Lipid nanoparticles (LNPs) are a nonviral delivery system that could enable a facile strategy to modify MKs with a variety of nucleic acid payloads. ObjectivesTo investigate whether LNP can transfect cultured hematopoietic stem/progenitor cell–derived MKs to express exogenous proteins and induce functional changes. MethodsMK and MK progenitors differentiated from cord blood–derived hematopoietic stem/progenitor cells were treated with LNP formulations containing messenger RNA and resembling the clinically approved LNP formulations. Transfection efficiency was assessed through flow cytometry by expression of enhanced green fluorescent protein. Functional changes to the MKs were assessed through rotational thromboelastometry by expression of exogenous coagulation factor (F)VII, a representative physiologically relevant protein. ResultsLNP enabled transfection efficiencies of 99% in MKs and did not impair MK maturation, viability, and morphology. MKs engineered to express exogenous FVII decreased clotting time in FVII-deficient plasma following clot initiation. ConclusionThis approach provides an easy-to-use modular platform to genetically modify MK and MK progenitors, which can be potentially extended to producing genetically modified cultured platelets.

Synthesis and anticoagulant activity of methyl 2-{2-[2-(4,4,6-trimethyl-2-oxo-4H-pyrrolo[3,2,1-ij]quinolin-1(2H)-ylidene)hydrazineyl]-4-oxothiazol-5(4H)-ylidene}acetates against blood clotting factors Xa, XIa and thrombin

Synthesis and anticoagulant activity of methyl 2-{2-[2-(4,4,6-trimethyl-2-oxo-4H-pyrrolo[3,2,1-ij]quinolin-1(2H)-ylidene)hydrazineyl]-4-oxothiazol-5(4H)-ylidene}acetates against blood clotting factors Xa, XIa and thrombin

Clinical, Laboratory Aspects and Management of Factor X Deficiency.

Coagulation factor X (FX), originally named Stuart-Prower factor, plays a pivotal role in the coagulation cascade, activating thrombin to promote platelet plug formation and prevent excess blood loss. Genetic variants in F10 may lead to FX deficiency and to impaired coagulation. FX variants are phenotypically classified as being type I, with the concomitant reduction of FX coagulant activity and FX antigen levels or type II, corresponding to a reduction in activity with normal antigen plasma levels. Patients affected with FX deficiency tend to be one of the most seriously affected among those with rare bleeding disorders. They show a variable bleeding tendency strongly associated with FX coagulant activity levels in plasma and may present, in the severe form of the deficiency, life-threatening symptoms such as gastrointestinal and umbilical stump bleeding and intracranial hemorrhages or central nervous system bleeding. Treatment of FX deficiency was originally based on the replacement of the missing factor using fresh frozen plasma, cryoprecipitate and prothrombin complex concentrates; however, a plasma-derived concentrate, shown to be safe and effective in clinical trials, is now available. In addition, novel nonreplacement therapy such as small interference RNA, gene therapy, drug repurposing, and gene editing may also represent novel therapeutic approaches for FX deficiency, but further, much focused studies are needed before considering this emerging therapy in such patients.

Clinical, Laboratory, Molecular, and Reproductive Aspects of Combined Deficiency of Factors V and VIII.

Congenital combined deficiency of factor V (FV) and factor VIII (FVIII; F5F8D, OMIM 227300) is a rare hereditary coagulopathy and accounts for approximately 3% of cases of rare coagulation disorders. The prevalence of this disease in the general population is estimated to be 1:1,000,000 and is significantly higher in regions where consanguineous marriages are permitted, such as the Mideast and South Asia. The disease has an autosomal recessive mode of inheritance and therefore occurs with an equal incidence among males and females. Heterozygous mutation carriers usually do not have clinical manifestations. The molecular basis of this disease differs from that of stand-alone congenital deficiencies of FVIII and FV. F5F8D is caused by mutations in either LMAN1 or MCFD2, which encode components of a cargo receptor complex for endoplasmic reticulum to Golgi transport of FV and FVIII, leading to defects in an intracellular transport pathway shared by these two coagulation factors. Congenital combined deficiency of FV and FVIII is characterized by decreased activities of both FV and FVIII in plasma, usually to 5 to 30% of normal. Clinical manifestations in most cases are represented by mild or moderate hemorrhagic syndrome. The simultaneous decreases of two coagulation factors present complications in the diagnosis and management of the disease. In female patients, the disease requires a special approach for family planning, pregnancy management, and parturition. This review summarizes recent progress in clinical, laboratory, and molecular understanding of this disorder.

Coagulation factors VIII and factors IX testing practices in China: Results of the 5-year external quality assessment program

Background and aimsTesting for coagulation factors VIII (FVIII) and IX (FIX) plays significant importance in the diagnostic and treatment of hemophilia A and B. External quality assessment (EQA) scheme aimed to assess the participants’ performance of testing for coagulation factors and identify shortcomings in clinical practice. This study aimed to investigate the performance trends of the participating laboratories in China national external quality assessment Scheme (China NEQAS) for FVIII and FIX over a five-year period (2019–2023). Materials and methodsA total of ten external quality assessment (EQA) rounds were conducted from 2019 to 2023 in the China NEQAS for FVIII and FIX. The distribution of method, reagent and instrument were calculated. The trends of method- specific inter-laboratory coefficient of variation (CV) and pass rates were analyzed over 5 years. The dilutions for coagulation factor testing were also investigated. ResultsAll laboratories use one-stage assays to detect FVIII and FIX activity. The inter-laboratory overall CV decreased year by year (10.9 % to 9.3 % for FVIII and 13.5 % to 10.2 % for FIX), and the laboratory pass rate steadily increased (88.0 % to 93.4 % for FVIII and 81.3 % to 92.7 % for FIX). The majority of laboratories employed a single dilution methodology for the assessment of FVIII and FIX activity. The interlaboratory CV was elevated for the Siemens reagent (Actin FSL) during analysis of moderately abnormal FIX concentrations of EQA samples in most batches. ConclusionsThe implementation of the external quality assessment has contributed to facilitate the enhancement of testing quality. Chromogenic assay is a supplement to accurate determination when necessary. Laboratories may choose to perform dilution tests or direct assays to identify the presence of inhibitors, particularly when they are suspected.