Association of Magnesium Deficiency and Reduction in Blood Pressure After Chemotherapy in Previously Hypertensive Cancer Patients: The Role of Chemotherapy and Magnesium Levels.

Background and Objectives: A commonly observed phenomenon in outpatient oncological patients is the appearance of hypotension not attributable to other causes in hypertensive patients undergoing oncological treatment. Once antihypertensive treatment is discontinued, patients remain normotensive after the oncological treatment ends. The objective of this research is to analyze our experience with this phenomenon and try to provide an explanation. Materials and Methods: A retrospective case-control study was conducted with a total sample of 302 hypertensive oncological patients, with cases presenting symptomatic hypotension and controls not. Descriptive and inferential statistics were performed, with the latter focusing on studies by Odds Ratio, Chi-square, Z test for comparison of two proportions, and multivariate regression. Results: Regarding the results obtained, it is noteworthy that in both the univariate and multivariate models, treatment with cisplatin showed statistical significance (Univariate, OR 3.06 (CI 1.82-5.11). Z 4.45, p < 0.0001; multivariate, p < 0.001, Nagelkerke R2 74.8%). Cisplatin treatment and the study phenomenon were correlated with magnesium levels (Chi-square 8.2, p = 0.017), relating hypotension to hypertensive patients with low magnesium levels. Conclusions: CDDP treatment is associated with hypotension or normotension in previously hypertensive cancer patients. This may be related to peripheral vascular fragility induced by oncological drugs, leading to reduced vascular resistance. Although magnesium deficiency is generally linked to hypertension, chemotherapy-related shifts in magnesium levels due to impaired renal handling may play a role. These findings may help improve the understanding of blood pressure regulation in oncology patients.