Background and aimsPseudomyxoma peritonei (PMP) is a rare malignancy that lacks a highly sensitive and specific biomarker for its diagnosis. Identifying reliable serum markers is crucial for improving the diagnostic accuracy and management of PMP. This study aims to explore the diagnostic value of serum growth differentiation factor 15 (GDF-15) in patients with PMP. Material and methodsWe carried on a 1:1 matched case-control study. 44 patients with PMP hospitalized in Aerospace Center Hospital were recruited as cases, and 44 sex- and age-matched apparently healthy participants were selected as controls. The serum GDF-15 concentrations were tested using an ELISA method. The diagnostic value of GDF-15 in PMP patients was assessed by receiver operating characteristic (ROC) curve analysis. ResultsThe median serum GDF-15 level in PMP patients was 1192.77 (843.03–1879.06) pg/mL, notably higher than that in healthy controls [533.27 (410.46–641.47) pg/mL] (P<0.001). The area under the curve (AUC) of serum GDF-15 for PMP diagnosis was 0.907, the optimal diagnostic threshold value was 644.58 pg/mL, the sensitivity was 93.18 %, and the specificity was 77.27 %. The AUC of GDF-15 combined with carbohydrate antigen 125 (CA125) was larger than that of GDF-15 alone (P=0.027), and the sensitivity and specificity achieved 86.36 % and 95.45 %. GDF-15 levels showed a significant correlation with age (P=0.042), with younger PMP patients exhibiting notably lower concentrations of GDF-15 compared to older patients. ConclusionSerum GDF-15 could become a new marker for the PMP diagnosis. The combination of GDF-15 and CA125 demonstrated superior diagnostic performance for PMP compared to GDF-15 alone, achieving a sensitivity of 86.36% and a specificity of 95.45%.