The Effect of Different Intraperitoneal Hyperthermic Chemotherapy (HIPEC) Regimens on Serum Electrolyte Levels: A Comparison of Oxaliplatin and Mitomycin C.

Background and Objectives: This study aimed to compare the effects of HIPEC procedures using oxaliplatin and mitomycin C on serum electrolyte, glucose, and lactate levels, with a specific focus on the carrier solutions employed. Materials and Methods: A retrospective analysis was performed on 82 patients who underwent cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC) for colorectal peritoneal metastases. Patients were assigned to one of two groups based on the chemotherapeutic agent used: oxaliplatin (n = 63) or mitomycin C (MMC, n = 19). The oxaliplatin group was further subdivided based on the carrier solution used: 5% dextrose (D5W, n = 29) or peritoneal dialysate (n = 34). The assignment of regimens was based on institutional protocols and surgeon preference. Pre- and post-HIPEC serum levels of sodium, potassium, bicarbonate, glucose, and lactate were compared. Results: Significant biochemical changes were observed across groups, depending on both the chemotherapeutic agent and carrier solution. In the MMC group (peritoneal dialysate), only lactate increased significantly post-HIPEC (p = 0.001). In the oxaliplatin-peritoneal dialysate group, significant changes were observed in bicarbonate (p = 0.009), glucose (p = 0.001), and lactate (p < 0.001), whereas sodium and potassium remained stable. The oxaliplatin-D5W group showed significant changes in all parameters: sodium (p = 0.001), potassium (p = 0.001), bicarbonate (p = 0.001), glucose (p < 0.001), and lactate (2.4 → 7.6 mmol/L, p < 0.001). Between-group comparisons revealed significant differences in sodium, potassium, glucose, and lactate changes (p < 0.05), but not in bicarbonate (p = 0.099). Demographic and clinical characteristics-including age, sex, primary disease, ICU stay, and 90-day mortality were similar across groups. Conclusions: The use of dextrose-containing solutions with oxaliplatin was associated with marked metabolic disturbances, including clinically meaningful hyponatremia, hypokalemia, and hyperglycemia in the early postoperative period. These findings suggest that the choice of carrier solution is as important as the chemotherapeutic agent in terms of perioperative safety. Closer postoperative electrolyte monitoring is recommended when using dextrose-based regimens. The retrospective design and sample size imbalance between groups are acknowledged limitations. Nonetheless, this study offers clinically relevant insights and lays the groundwork for future prospective research.