MO123: The Correlation of Platinum-Based Chemotherapy with Decreased Blood Ionized Magnesium in Cancer Patients
Authors: Jiang Da , LI Ying , Huang Fang , Zhou Xinliang , Qiu Wei 
Published: May 2022

Abstract

BACKGROUND AND AIMS
Platinum-based agents are prescribed as backbone chemotherapy for lung, colorectal, esophagogastric, breast, testicular and ovarian cancers, among others. Renal excretion of platinum-based agents is mediated by the cellular transporters localized in renal tubules. Accumulation of the agents in tubular cells leads to inflammation, injury and cell death. Meanwhile, one-tenth of total body magnesium (Mg) is filtered by kidney during a 24-h period, and 80–95% of the filtered Mg is reabsorbed by nephron segments, including the proximal tubule, thick ascending limb of the Loop of Henle and distal convoluted tubule. Thus, there is a potential that renal Mg loss can happen as a result of direct injury to those major Mg absorption sites in renal tubules by platinum-based agents. Mg serves as a cofactor in over 300 enzymes and is essential for many biological processes. Thus, monitoring for hypomagnesemia is important in these patients. We compared Mg loss in patients undergoing platinum-based therapy with those being treated with non-platinum-based agents to evaluate the potential for Mg loss in platinum-based chemotherapy. We evaluated Mg status using an assay for ionized Mg (iMg), which is the physiologically active form of Mg.

METHOD
A total of 78 patients suffering from various tumours and taking chemotherapy in the Fourth Hospital of Hebei Medical University (Hebei Tumor Hospital), China, between January and July 2019 were enrolled in the study. For each patient, blood iMg level was tested twice using Stat Profile Prime Plus® Critical Care Analyzer (Nova Biomedical, Waltham, MA, USA). The first iMg testing was conducted upon admission to the hospital before chemotherapy. The second iMg testing was conducted before discharge from the hospital after the chemotherapy course was completed. Generally, the time difference between the two iMg tests was several weeks up to 1 month. The difference of iMg levels in the two tests was evaluated, and the correlation of the degrees of iMg decrease after the chemotherapy course with the platinum-based agent group and non-platinum-based agent group was analysed using the Chi-square test.

RESULTS
Most of the patients suffered from lung cancer, followed by breast, esophagogastric, colon and rectal cancers. There were also sparse cases of other cancers. A total of 44 of them received a platinum-based agent, and 34 received non-platinum-based agents only. The platinum-based agents taken were cisplatin, oxaliplatin, carboplatin and nedaplatin. For patients aged over 60 years, the decrease in blood iMg levels in the platinum-based group was significantly greater than that in the non-platinum-based group (x2 = 4.353 and P &lt; .05 for iMg decrease &gt; 0.01 mmol/L, x2 = 4.403 and P &lt; .05 for iMg decrease &gt; 0.05 mmol/L, and x2 = 4.237 and P &lt; .05 for iMg decrease &gt;0.1 mmol/L). For male patients at all ages, the decrease in blood iMg levels in the platinum-based group was also significantly greater than that in the non-platinum-based group (x2 = 9.879 and P &lt; .01 for iMg decrease &gt;0.01 mmol/L, x2 = 11.481 and P &lt; .001 for iMg decrease &gt;0.01 mmol/L, and x2 = 10.000 and P &lt; .01 for iMg decrease &gt;0.1 mmol/L). There was no statistical significance in blood iMg levles between the platinum-based group and the non-platinum-based group for patients below 60 years old. There was also no statistical significance in blood iMg levels between the platinum-based group and the non-platinum-based group for all the female patients at all ages.

CONCLUSION
Our study showed that all patients aged over 60 years and male patients at all ages were liable to a decrease in blood iMg levels if treated with the platinum-based chemotherapy rather than non-platinum-based chemotherapy. It suggests that the iMg reabsorption process facilitated by the renal tubules is more likely to be affected by the platinum-based agents in those groups of patients. Monitoring renal function and blood iMg levels is important for patients receiving platinum-based chemotherapy.