Understanding the influence of transfusion and blood loss on tranexamic acid concentration in scoliosis surgery with blood loss

Aims Tranexamic acid (TXA) stabilizes clot formation by inhibiting fibrin degradation and improves postoperative outcomes. However, rare adverse events (e.g., thrombosis, seizures) warrant dose–risk evaluation. This study examines how perioperative blood loss and transfusion practices affect TXA concentrations during paediatric scoliosis surgery. Methods Forty‐three patients undergoing scoliosis surgery with TXA were retrospectively analysed. The study assessed the impact of packed red blood cell (PRBC) transfusion on plasma TXA levels and whether maintaining concentrations ≥10 μg/mL correlated with intraoperative blood loss. TXA levels were measured using UHPLC–MS/MS. Results Median TXA concentration 30 min after the loading dose was 37.8 μg/mL (IQR: 31.4–39.6 μg/mL), decreasing to 10.6 μg/mL (IQR: 9.7–13.5 μg/mL) after transfusion. At surgery end, the mean concentration was 12.9 ± 2.5 μg/mL. Thirty‐one patients maintained TXA levels ≥10 μg/mL, associated with ~80% inhibition of tissue plasminogen activator . Of six patients below this threshold, five had received transfusions. A significant correlation was found between higher intraoperative blood loss and lower TXA levels, consistent with a dilutional effect. In contrast, among patients with TXA ≥ 10 μg/mL, correlation with blood loss was weak (Spearman's ρ = −0.11, p = 0.54). Findings suggest homologous PRBC transfusion reduces plasma TXA through volume expansion. Conclusions Sustaining TXA concentrations >10 μg/mL is essential for antifibrinolytic efficacy and haemostatic outcomes. The dilutional impact of PRBC transfusion underscores the need for intraoperative dose adjustment. Optimizing TXA dosing requires understanding pharmacokinetics and patient variability.