Thrombomodulin in patients with mild to moderate bleeding tendency

How to investigate mild to moderate bleeding disorders and bleeding disorder of unknown cause

A bleeding tendency is one of the most common complaints observed by hematologists. It is challenging to differentiate a clinically insignificant bleeding from a bleeding phenotype that requires hemostatic evaluation and medical intervention. A thorough review of personal and familial history, objective assessment of bleeding severity using a bleeding assessment tool, and a focused physical examination are critical to correctly identifying suspected patients with mild to moderate bleeding disorders (MBDs). A basic laboratory work-up should be performed in all patients referred for a bleeding tendency. If a hemostatic abnormality is found such as evidence of von Willebrand disease, a platelet function disorder, or a coagulation factor deficiency, more extensive testing should be performed to further characterize the bleeding disorder. Conversely, if all results are normal the patient is considered to have bleeding disorder of unknown cause (BDUC). For patients with BDUC, further evaluation may include non-routine testing to look for rare bleeding disorders not detected by routine hemostasis tests, such as thrombomodulin-associated coagulopathy, tissue factor pathway inhibitor-related bleeding disorder, hyperfibrinolytic-bleeding disorders or impaired tissue factor production. In this review, we summarize the stepwise diagnostic procedure in MBDs and provide some insights into the biological features of BDUC.

Activated protein C and free protein S in patients with mild to moderate bleeding disorders

BACKGROUND

Underlying mechanisms for bleeding and impaired thrombin generation (TG) and plasma clot formation (PCF) in patients with mild to moderate bleeding disorders (MBDs) are still to be elucidated, especially in bleeding disorder of unknown cause (BDUC). The role of the natural anticoagulants activated protein C (APC) and free protein S (PS) has not yet been investigated in this patient population.

AIMS

To analyze antigen levels of APC and PS in patients with MBDs and BDUC and investigate associations to clinical bleeding phenotype and severity as well as and hemostatic capacity.

METHODS

Antigen levels of APC and free PS were measured in 262 patients from the Vienna Bleeding Biobank (VIBB), a single-center cohort study, by ELISA and compared to 61 healthy controls (HC).

RESULTS

Antigen levels of APC were higher in MBD patients than in HC when adjusted for age, sex and BMI (median (IQR) 33.1 (20.6-52.6) and 28.6 (16.4-47.2) ng/mL). This was most pronounced in patients with BDUC (35.3 (21.7-54.3) ng/mL). No differences in PS antigen levels between patients and HC were seen overall, or according to specific diagnoses. Further, no association between APC or PS and bleeding severity or global tests of hemostasis or TG were identified, while paradoxically APC weakly correlated with shorter lag time and time to peak of PCF in BDUC.

CONCLUSION

Our data demonstrate increased antigen levels of APC in BDUC, which might contribute to the bleeding tendency in some patients and could be a future therapeutic target in BDUC.

Investigating patients for bleeding disorders when most of the "usual" ones have been ruled out

A State of the Art lecture titled "Investigating Patients for Bleeding Disorders When Most of the Usual Ones Have Been Ruled Out" was presented at the International Society on Thrombosis and Haemostasis Congress in 2023. Mild to moderate bleeding disorders (MBDs) in patients in whom no diagnosis of an established disorder, such as platelet function defect, von Willebrand disease, or a coagulation factor deficiency, can be identified are classified as bleeding disorders of unknown cause (BDUCs). Prospective data from the Vienna Bleeding Biobank and other studies have revealed a high proportion of BDUCs of up to 70% among patients with MBD who have a similar bleeding phenotype as other MBDs. As BDUC is a diagnosis of exclusion, the accuracy of the diagnostic workup is essential. For example, repeated testing for von Willebrand disease should be considered if von Willebrand factor values are <80 IU/dL. Current evidence does not support the clinical use of global assays such as thromboelastography, platelet function analyzer, or thrombin generation potential. Rare and novel bleeding disorders due to genetic variants in fibrinolytic factors or natural anticoagulants are rare and should only be analyzed in patients with specific phenotypes and a clear family history. In BDUC, blood group O was identified as a risk factor for increased bleeding severity and bleeding risk after hemostatic challenges. Future studies should improve the phenotypical characterization and ideally identify novel risk factors in BDUC, as a multifactorial pathogenesis is suspected. Finally, we summarize relevant new data on this topic presented during the 2023 International Society on Thrombosis and Haemostasis Congress.

Women with severe postpartum hemorrhage have a decreased endogenous thrombin potential before delivery

BACKGROUND

Severe postpartum hemorrhage (PPH), defined as a blood loss ≥1000 mL, is associated with maternal morbidity and mortality.

OBJECTIVES

We aimed at characterizing coagulation properties of predelivery plasmas from pregnant women with thrombin generation assay and hemostatic biomarkers (plasminogen activator inhibitor-1, tissue factor [TF], and thrombomodulin).

METHODS

A nested case-control study was conducted within the "Study of Biological Determinants of Bleeding Postpartum," a French prospective cohort study, in order to compare women with severe PPH (cases) and controls matched for age, body mass index, term, and mode of delivery. Plasma was collected at entry in the delivery room, and blood loss was measured objectively. The predelivery endogenous thrombin generation potential (ETP) was measured in plasma using calibrated automated thrombinography and low TF concentration. Hemostatic biomarkers were measured using ELISA kits.

RESULTS

A total of 142 women (71 cases and 71 controls) were investigated. There was no difference in the median lag phase, thrombin peak, and time to peak between cases and controls. However, median predelivery ETP was lower in cases than in controls (2170 vs 2408 nM.min, P < .0001), independently of mode of delivery and PPH etiology. Median plasminogen activator inhibitor-1 and TF levels were higher in cases compared with controls (107.4 vs 68.1 ng/mL, P = .0003; 34.4 vs 27.4 pg/mL, P = .007), whereas thrombomodulin levels did not differ between the 2 groups.

CONCLUSION

Among thrombin generation assay parameters, predelivery ETP levels may have a predictive value for severe PPH.

Risk factors for future bleeding in patients with mild bleeding disorders: longitudinal data from the Vienna Bleeding Biobank

BACKGROUND

The future bleeding risk, especially after hemostatic challenges, and thus the requirement for hemostatic treatment in patients with mild-to-moderate bleeding disorders (MBDs) is largely unknown.

OBJECTIVES

This study aimed to prospectively examine the recurrence of bleeding symptoms and clinical risk factors for future bleeding in patients with MBD, including patients with bleeding disorder of unknown cause (BDUC).

METHODS

Bleeding symptoms of patients with MBD included in the Vienna Bleeding Biobank were re-evaluated at in-person follow-up visits or by mail.

RESULTS

In total, 392 patients, including 62.8% with BDUC, were investigated for the recurrence of bleeding events. During the follow-up time of median (IQR) 4.3 years (2.6-6.7), 72% of patients had at least 1 bleeding event. Most persistent bleeding manifestations were hematomas (n = 146/245, 59.6%) and bleeding from small wounds (n = 69/141, 48.9%), followed by epistaxis (n = 42/132, 31.8%), oral mucosal bleeding (n = 26/87, 29.9%), and joint bleeding (n = 7/14, 50.0%). Patients with previous postinterventional bleeding had a significantly increased risk for bleeding events after surgery (n = 33/114, 29.0 %) or tooth extraction (n = 16/39, 41.0%). A high bleeding score (OR [95% CI], 1.14 [1.05 to 2.94], per 1 unit) and follow-up time (OR [95% CI], 1.23 [1.12 to 1.36], per 1 year) were independently associated with any bleeding event. For bleeding after hemostatic challenges, blood group O (OR, 3.17 [1.57 to 6.40]), previous postsurgical bleeding (OR, 2.40 [1.06 to 5.46]), and an established diagnosis (OR, 2.07 [1.04 to 4.10]) were independent risk factors.

CONCLUSION

Patients with MBD have a high risk for recurrent bleeding. This encourages prophylactic hemostatic treatment in patients with MBD, particularly when they face hemostatic challenges.