Thrombocytosis is desirable in polytrauma: Natural history and clinical outcomes

BACKGROUND: Thrombocytosis in major trauma patients has been reported with equivocal clinical relevance. We aimed to describe the incidence and natural history of thrombocytosis in intensive care unit (ICU)-admitted polytrauma patients at risk of multiple-organ failure (MOF). METHODS: A 19-year retrospective study ending in December 2023 was performed on a Level 1 center's prospective institutional MOF database. All adults with an Injury Severity Score (ISS) of >15 and ICU patients who survived >48 hours were included. All adults with nonmechanical trauma, isolated traumatic brain injury (TBI), or spinal cord injury or those without sequential platelet monitoring were excluded. Platelet counts were collected until death, discharge, or 28 days. Thrombocytosis and extreme thrombocytosis (ET) were defined as >450,000/μL and >1,000,000/μL. Descriptive statistics were calculated, and mortality, MOF, and venous thromboembolic outcomes were compared between groups. For mortality, multivariable logistic regression was performed adjusting for age, ISS, TBI, and systolic blood pressure. RESULTS: A total of 797 patients were included (age, 48.8 years; 75% male; 96% blunt; median ISS, 29). Incidence of thrombocytosis was 63% (503 of 797 patients) with ET of 16.5% (83 of 797 patients). Thrombocytosis patients had higher admission counts peaking at 14 to 17 days. Groups did not differ in sex and TBI severity. Thrombocytosis patients were younger and had lower systolic blood pressure on admission and longer median ICU and hospital length of stay (8 vs. 6 and 27 vs. 12, p < 0.005). Incidence of MOF and venous thromboembolism did not differ. Mortality was lower in the thrombocytosis group (7.6% vs. 18%, p < 0.001). One ET patient died. Multiple-organ failure developed in 176 (22%) with incidence of thrombocytosis of 5% (103 of 176 patients). The mean Denver scores between thrombocytosis and no thrombocytosis did not differ, but mortality was lower in the thrombocytosis group (adjusted odds ratio, 0.05; 95% confidence interval, 0.01-0.15). CONCLUSION: Thrombocytosis (63%) is frequent in polytrauma patients and is associated with favorable outcomes without higher risk for complications. Early thrombocytosis and rising platelet trajectories may act as a surrogate marker for better chance to survive, and its therapeutic potential warrants detailed exploration. ( J Trauma Acute Care Surg . 2026;100:922-928. Copyright © 2026 Wolters Kluwer Health, Inc. All rights reserved.). LEVEL OF EVIDENCE: Retrospective and observational study, level III.