Normal aPTT in children with mild factor XI deficiency.

Area of Science:

• Pediatric Hematology
• Hemostasis and Thrombosis
• Coagulation Disorders

Background:

• The activated partial thromboplastin time (aPTT) is a key laboratory test in the diagnostic workup of bleeding disorders.
• Previous studies suggest that factor XI deficiency may not always prolong the aPTT, but data in pediatric populations are limited.
• Understanding the relationship between factor XI activity and aPTT in children is crucial for accurate diagnosis.

Purpose of the Study:

• To investigate the prevalence of a normal aPTT in children diagnosed with factor XI deficiency.
• To determine if a normal aPTT can exclude the need for factor XI activity testing in pediatric patients with bleeding symptoms.

Main Methods:

• Retrospective review of an institutional database.
• Identification of pediatric patients with a confirmed diagnosis of factor XI deficiency.
• Analysis of activated partial thromboplastin time (aPTT) results in this cohort.

Main Results:

• Seven children with factor XI deficiency were identified.
• Four out of seven children (approximately 57%) with factor XI deficiency exhibited a normal aPTT.
• This indicates that a normal aPTT is observed in a significant proportion of pediatric cases.

Conclusions:

• A normal activated partial thromboplastin time (aPTT) does not reliably exclude factor XI deficiency in children.
• Clinicians should consider factor XI activity testing in pediatric patients with unexplained bleeding, even with a normal aPTT.
• These findings highlight the importance of considering factor XI deficiency in the differential diagnosis of bleeding disorders in children.