Marc Fouassier

Background The bleeding risk of patients with mild platelet function disorders is difficult to assess and their phenotype remains ill‐explored. Aim This study was designed to establish a comprehensive biological phenotype of patients with mild platelet function disorders. Methods Twenty patients were included with persistent abnormal light transmission aggregometry (LTA). The ISTH bleeding assessment tool (ISTH‐BAT) was assessed to identify laboratory analyses associated with an abnormal hemorrhagic score. Results The majority of patients had defects that might affect Gαi protein signaling pathways or minor abnormalities. No LTA nor flow cytometry parameters were associated with an above‐normal hemorrhagic score. However, prothrombin consumption, which corresponds to the ratio of serum residual factor II to plasma residual factor II, was significantly higher ( p = .006) in the abnormal ISTH‐BAT group (mean = 14%, SD = 6) compared with the normal ISTH‐BAT group (mean = 8%, SD 4). Prothrombin consumption was significantly associated with ISTH‐BAT score ( r = .5287, IC 95% 0.0986–0.7924, p = .0165). Conclusion In this group of patients, there was an association between a pathological bleeding score and increased prothrombin consumption. This test could be used as an additional indicator of platelet function abnormality liable to be related to bleeding risk.