[Clinical characteristics and treatment outcomes of adult patients with phytosterolemia presenting with Thrombocytopenia].

<b>Objective:</b> To analyze the clinical characteristics of adult patients with phytosterolemia presenting with thrombocytopenia as the initial manifestation. <b>Methods:</b> A retrospective analysis was conducted on eight adult patients with phytosterolemia who visited Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, from December 2020 to December 2023. <b>Results:</b> ① The participants consisted of 2 (25%) male and 6 (75%) female patients, with a median age at diagnosis of 55 years (range: 29-66 years). The median duration from the discovery of thrombocytopenia to diagnosis was 10 years (range: 0.2-50 years). ② Compared with the normal control group (30 healthy adult volunteers) and the immune thrombocytopenia (ITP) control group (20 patients with ITP), patients with phytosterolemia exhibited significantly higher mean platelet volume and large platelet ratio. Peripheral blood smears revealed that the mean platelet diameter and the proportion of large platelets (diameter> 4 μm) were significantly higher in patients with phytosterolemia than those in the normal and ITP control groups (<i>P</i><0.01). ③ After a low-plant-sterol diet and ezetimibe treatment, five patients demonstrated decreased serum sitosterol and campesterol levels, increased hemoglobin concentration and platelet counts, and reduced platelet volume. <b>Conclusion:</b> Adult-onset phytosterolemia presenting with thrombocytopenia as the initial manifestation is prone to misdiagnosis. The presence of hemolytic anemia, splenomegaly, increased large platelets and schistocytes on peripheral blood smears, and xanthomas are crucial diagnostic indicators. Restricting dietary plant sterol intake and using ezetimibe to inhibit sterol absorption effectively lowers serum plant sterol levels and improves hematological abnormalities.