The Effect of Lupus Anticoagulant Detected in Children with Respiratory Tract Infection on in vitro Coagulation Time

Abstract

Background: This study was conducted in order to investigate the prevalence of lupus anticoagulant (LA) in children with respiratory tract infection and to evaluate the effect of LA on in vitro coagulation time. Methods: This study included 46 subjects, showing positivity to Mycoplasma pneumoniae (MP) IgM antibody and 37 subjects positive to various respiratory viruses (RV). The titer of LA and PT/aPTT were examined and investigated the effect of LA on PT/aPTT. Results: None of the subjects showed any evidence of bleeding or thrombosis during conduct of the study. Positive LA (LA titer ≥1.34) was significantly more frequent in MP group (39.1%) than RV group (18.9%)(P＜0.05). Total prevalence of positive LA was 30.1%, among them 22.9% was low positive LA (1.34≤LA＜2.0) and 7.2% was high positive LA (LA≥2.0). Low LA positive group showed only mild PT prolongation (13.0＜PT ＜20 sec) and the prevalence was more frequent than LA negative group (P＜0.05). However, aPTT prolongation was not more frequent in low LA positive group than LA negative group (P＞0.05). All subjects of high LA positive group showed severe prolongation of aPTT (≥60 sec), however, severe PT prolongation (≥20 sec) was not noticed. Conclusion: The prevalence of LA was relatively high in children with respiratory tract infection, however, most of them are mildly elevated. Low LA positivity was related to the mild prolongation of PT. But high LA positivity markedly prolongs the aPTT without marked prolongation of PT.