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Measurement of Factor V Activity in Human Plasma Using a Microplate Coagulation Assay
Published on: September 9, 2012
Bleeding Symptoms in Pediatric Patients with Congenital FVII Deficiency and Correlation to Thrombin Generation Assay
Giovina Di Felice1, Sonia Iavarone2, Anna Lisa Montemari1
1Clinical Laboratory Unit, Bambino Gesù Children's Hospital, IRCCS, 00165 Rome, Italy.
Insights
Inherited factor VII deficiency (FVII) is a rare bleeding disorder. Thrombin generation assays may help assess bleeding risk in children with mild FVII deficiency, though severity prediction remains challenging.
Area of Science:
- Hematology
- Pediatric Medicine
- Rare Diseases
Background:
- Inherited factor VII deficiency (FVII) is the most common rare bleeding disorder.
- A significant portion of patients with FVII levels between 20-50% remain asymptomatic, complicating the prediction of bleeding risk.
- There is a lack of precise correlation between FVII plasma levels and the clinical bleeding phenotype.
Purpose of the Study:
- To investigate the utility of thrombin generation assays in assessing bleeding risk in children with mild FVII deficiency (FVII levels 20-35%).
- To compare thrombin generation parameters between children with mild FVII deficiency and healthy controls.
- To explore the relationship between thrombin generation, FVII levels, and the presence or absence of bleeding symptoms in pediatric patients.
Main Methods:
- Recruitment of 19 children and adolescents with FVII levels of 20-35% and 33 healthy controls.
- Laboratory analysis including thrombin generation, prothrombin time, activated partial thromboplastin time, fibrinogen, and FVII levels.
- Categorization of patients based on the presence or absence of bleeding symptoms, irrespective of bleeding scores.
Main Results:
- Significant differences were observed in the lag time ratio (p < 0.01) and tt-peak ratio (p < 0.05) between patients and controls.
- No significant differences were found in other parameters like endogenous thrombin potential (ETP).
- When categorized by symptoms, both lag time ratio (p = 0.01) and tt-peak ratio (p < 0.05) differed significantly between symptomatic and asymptomatic patients, with increased vel. index % in asymptomatic individuals (p < 0.05).
Conclusions:
- Thrombin generation assays show potential as a tool for evaluating bleeding risk in children with mild FVII deficiency (20-35%).
- Specific thrombin generation parameters, such as lag time ratio and tt-peak ratio, are sensitive indicators in this population.
- While useful for risk assessment, thrombin generation assays cannot precisely predict the severity of bleeding in children with FVII deficiency.
Abstract:
Inherited factor VII deficiency is the most common rare bleeding disorder, affecting about 1/500,000 individuals without gender predilection. Most of the patients with FVII 20-50% are asymptomatic, but post-traumatic or post-surgical bleeding may often occur since there is not an exact correlation between FVII plasma levels and the bleeding phenotype. We enrolled 19 children and adolescents with FVII levels of 20-35% and 33 controls. Laboratory data collected included thrombin generation, prothrombin time, activated partial thromboplastin time, fibrinogen, and FVII levels. In our study, we found a statistical difference in the lag time ratio (p < 0.01) and tt-peak ratio (p < 0.05) between patients and controls but no difference in the other parameters, such as the endogenous thrombin potential (ETP). However, when we categorized patients, regardless of their bleeding scores, as presenting symptoms and having no symptoms, both the lag time ratio (p = 0.01) and tt-peak ratio (p < 0.05) were significantly different, and the vel. index % showed increased levels in patients without symptoms (p < 0.05). This study shows that thrombin generation may be a useful tool in assessing the risk of bleeding symptoms in children with an FVII deficiency categorized in the mild category (20-35%), although we cannot predict the severity of the bleeding.
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