567 Background: The International Metastatic RCC Database Consortium (IMDC) criteria are widely used for risk stratification in metastatic renal cell carcinoma (RCC), but their role in non-metastatic RCC is less defined, especially as a biomarker of recurrence. This study seeks to evaluate (1) the prevalence of IMDC abnormalities in non-metastatic RCC patients (nmRCCC), (2) the impact of nephrectomy on the normalization of these criteria, and (3) the association between post-operative IMDC abnormalities and oncological outcomes. Methods: Data from the Canadian Kidney Cancer Information System (CKCis) were analyzed to identify non-metastatic RCC patients diagnosed between January 2011 and April 2024 who underwent nephrectomy after diagnosis. Laboratory tests were evaluated preoperatively (within 6 months before surgery) and postoperatively (between 2 and 15 months). Univariable and multivariable analyses were performed to assess the association with overall survival, recurrence-free survival, and cancer-specific survival. Results: A total of 1,804 patients were analyzed, with 65.7% male and mean age was 62.5y. Tumors pathological characteristics were: pT1 (69.2%), pT2 (5.6%), pT3 (1.8%), pT4 (0.28%); tumors necrosis (21.8%); mean tumor size (4.7cm) and clear cell carcinoma (73.1%). Preoperative hemoglobin (Hb), neutrophils, platelets (Plt), and corrected calcium (Ca 2+ ) IMDC criteria abnormalities were identified in 19.4, 9.6, 4.3, and 3.2% of patients, respectively. After surgery, 45.4, 79.8, 80.4, and 76.9% of these abnormal cases normalized, respectively. Among patients with normal preoperative Hb, neutrophils, Plt, and Ca 2+ , 9.65, 4.4, 1.0, and 1.6% developed postoperative IMDC criteria abnormalities, respectively. In multivariate analysis, patients with normal Hb, neutrophils, and Ca 2+ , both pre- and postoperatively, had an increase in overall survival (OS) compared to those with abnormal postoperative values. Hazard ratios (HR[95%CI]) for increased OS were 3.6[2.8-4.7], 2.1[1.7-2.7] and 3.5[1.5-43.1], respectively, compared to those with abnormal postoperative values. Furthermore, those with normal Hb, neutrophils, Plt, and Ca 2+ , both pre- and postoperatively, had an increase in cancer-specific survival (CSS) with HR of 3.3, 4.3, 8.0 and 5.7 (p<0.05),indicating a significantly higher CSS probability than patients with abnormal postoperative values. Conclusions: Abnormal IMDC laboratory criteria are frequently found in nmRCC, especially anemia, and most normalize after surgery. Finding abnormal IMDC laboratory criteria post-surgery is associated with decreased CSS and OS. This knowledge may be useful in stratifying patients for intensified monitoring or for future adjuvant therapy clinical trials.