β‐ TP For Diagnosing CSF Leak After the Endoscopic Endonasal Approach Surgery for Sellar Tumors

ABSTRACT Objectives This study aimed to evaluate the diagnostic utility of quantitative beta‐trace protein (β‐TP) as an early biomarker for identifying postoperative cerebrospinal fluid (CSF) leaks following endoscopic endonasal approach (EEA) surgery for sellar tumors. Methods A total of 401 patients with sellar tumors who underwent EEA surgery at Huashan Hospital between April 2023 and July 2025 were enrolled. For postoperative hemostasis, expandable nasal sponges were placed in the posterior nasal cavity. Sponge extracts were collected on postoperative Day 2 to measure quantitative β‐TP concentrations using an immunoturbidimetric assay. Receiver operating characteristic (ROC) curve analysis was performed to determine the optimal β‐TP cutoff value and evaluate its diagnostic performance. Results Postoperative CSF leaks were confirmed in 16 patients (4.0%). The median β‐TP concentration in the CSF leak group was significantly higher than in the non‐CSF leak group (4.54 vs. 0.419 mg/L; p < 0.001). The area under the ROC curve was 0.941. Based on the maximum Youden index, the optimal diagnostic cutoff value for postoperative CSF leaks was established at 2.07 mg/L. This cutoff value yielded a sensitivity of 93.75%, a specificity of 99.48%, a positive predictive value of 88.24%, and a negative predictive value of 99.74%. Conclusion This study is the first to demonstrate that quantifying β‐TP concentrations in nasal sponge extracts provides a highly sensitive and specific method for diagnosing CSF leaks following EEA surgery. This approach offers distinct advantages for detecting occult CSF leaks, providing an effective threshold to guide early diagnosis and targeted clinical management. Level of Evidence 4.