Evaluation of Intravenous Magnesium Supplementation as Prophylaxis for Cisplatin-induced Hypomagnesemia

We assessed the effects of cisplatin-based chemotherapy, magnesium supplementation, probable contributory factors such as cisplatin cumulative dose and dose per cycle on serum magnesium levels. In this prospective randomized study, serum magnesium levels of 59 newly diagnosed adult patients receiving cisplatin-based chemotherapy were studied. The patients were randomly allocated to receive magnesium supplementation at a dose of 5 g IV per cycle (n=31) or to a control group (n=28). Serum magnesium levels <1.8 mg/dL were considered to indicate hypomagnesemia. The decrease in mean magnesium levels with continuing chemotherapy courses was significant in both groups with a more prominent decrease in the control group. In courses 4 and 5, mean magnesium levels were significantly higher among those who received magnesium supplementation than in the control group. Thirty patients (50.8%) had at least one incident of hypomagnesemia after beginning chemotherapy. All hypomagnesemia incidents were mild (mean 1.69, range; 1.52-1.79 mg/dL). Hypomagnesemia was more frequent in the control group (38.7% vs. 60.7%, P=0.09). Although age and sex had no significant effect on the incidence of hypomagnesemia, more hypomagnesemia incidents were observed in patients who received cisplatin in a single loading dose than in those who received the drug in divided doses for each cycle (71.4% % vs. 42.9%, P=0.056). Magnesium supplementation at a dose of 5 g per cycle partially compensated for cisplatin- induced magnesium loss. Monitoring magnesium levels and magnesium supplementation is warranted, especially for those undergoing protracted courses of cisplatin-based chemotherapy. Patients who receive the drug in a single loading dose might be more prone to magnesium loss.