Background: Lupus anticoagulant (LA) is an acquired IgG or IgM autoimmune antibody against platelet membrane phospholipids. LA is an important cause of aPTT prolongation in children.

Aims: Determination of LA prevalence in children and adolescences that were referred to the coagulation laboratory of IBTO.

Methods: During a period of 27 months (March 2014 to July 2016), all patients ≤ 18 years old who referred to our lab and had results of aPTT and lupus anticoagulant (LA) were evaluated. LA test panel was including screening tests (aPTT-LA and DRVVT screen) and as needed, the mixing study and confirmatory tests (Hexagonal assay and/or DRVVT confirm) all performed by STAGO reagents and instruments. In cases with positive LA, their follow-up refer to our lab were evaluated after 12 weeks.

Results: Our data revealed a LA prevalence of 2.5 % in all referred patients ≤ 18 y with aPTT result and 31 % in those who LA test was performed for them ( flow-chart 1). In more than half of the LA positive patients, the main reason for referring them to the lab was incidental finding of aPTT prolongation noticed before surgery or during hospitalization (table 1). Interestingly, 90 % of patients with positive LA , referred to the lab without any LA request by physician.

Conclusions: LA is not infrequent in children and adolescence however in most cases it is a transient problem without any significant clinical findings. About 90% of our cases were not suspected for LA by their physicians so it may be frequently missed in children clinically.

[Table 1: Demographic data and chief complaint of 51 patients with positive LA]

[Flow-chart 1]

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/the-prevalence-of-lupus-anticoagulant-in-children-and-adolescences-referred-to-the-reference-coagulation-laboratory-of-iranian-blood-transfusion-organization/