Preoperative Ionized Magnesium Levels and Risk of Acute Kidney Injury After Cardiac Surgery

Hee Byung Koh, Chan Young Jung, Hyung Woo Kim, Jae Yeol Kwon, Na Hye Kim, Hyo Jeong Kim, Jong Hyun Jhee, Seung Hyeok Han, Tae Hyun Yoo, Shin Wook Kang, Jung Tak Park

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Rationale & Objective: Although postoperative acute kidney injury (AKI) is a serious complication after cardiac surgery, preventive measures are limited. Despite the known association of preoperative low magnesium levels with cardiac surgery–related atrial fibrillation, the association between preoperative magnesium concentration and postoperative AKI has not been fully elucidated. This study evaluated the association between preoperative serum magnesium level and the development of AKI after cardiac surgery. Study Design: Retrospective observational cohort study. Setting & Participants: Patients aged ≥18 years who underwent cardiac surgery at 2 South Korean tertiary hospitals between 2006 and 2020 were identified from medical records. Patients with missing information, an estimated glomerular filtration rate < 15 mL/min/1.73 m2, receiving maintenance dialysis, or a history of AKI treated by dialysis within 1 year before surgery were excluded. Exposure: Preoperative serum magnesium levels. Outcome: Postoperative AKI within 48 hours after surgery, defined using the Acute Kidney Injury Network (AKIN) criteria, and dialysis-treated AKI within 30 days after surgery. Analytical Approach: Multivariable logistic regression analysis. Results: Among the 9,766 patients (median age, 64.0 years; 60.1% male), postoperative AKI and dialysis-treated AKI were observed in 40.1% and 4.3% patients, respectively. Postoperative AKI was more prevalent in patients with lower serum magnesium levels (44.9%, 41.4%, 39.4%, and 34.8% in quartiles 1-4, respectively). Multivariable logistic regression analysis revealed that the odds ratios (ORs) for postoperative AKI were progressively larger across progressively lower quartiles of serum magnesium concentration (adjusted ORs of 1.53 [95% CI, 1.33-1.76], 1.29 [95% CI, 1.12-1.48], 1.15 [95% CI, 1.01-1.31] for quartiles 1-3, respectively, relative to quartile 4, P for trend < 0.001). Preoperative hypomagnesemia (serum magnesium level < 1.09 mg/dL) was also significantly associated with AKI (adjusted OR, 1.39 [95% CI, 1.10-1.77]) and dialysis-treated AKI (adjusted OR, 1.67 [95% CI, 1.02-2.72]). Limitations: Causality could not be evaluated in this observational study. Conclusions: Lower serum magnesium levels were associated with a higher incidence of AKI in patients undergoing cardiac surgery.

Original languageEnglish
Pages (from-to)629-637.e1
JournalAmerican Journal of Kidney Diseases
Issue number5
Publication statusPublished - 2022 Nov

Bibliographical note

Funding Information:
Hee Byung Koh, MD, Chan-Young Jung, MD, Hyung Woo Kim, MD, Jae Yeol Kwon, MD, Na Hye Kim, MD, Hyo Jeong Kim, MD, Jong Hyun Jhee, MD, PhD, Seung Hyeok Han, MD, PhD, Tae-Hyun Yoo, MD, PhD, Shin-Wook Kang, MD, PhD, and Jung Tak Park, MD, PhD. Conception and design: HBK, JTP; data acquisition: HBK, C-YJ, HWK, JHJ; statistical analysis: HBK, JYK, NHK, HJK; data interpretation: HBK, JHJ, SHH, T-HY, S-WK, JTP; supervision: SHH, T-HY, S-WK, JTP. Each author contributed important intellectual content during manuscript drafting or revision and agrees to be personally accountable for the individual's own contributions and to ensure that questions pertaining to the accuracy or integrity of any portion of the work, even one in which the author was not directly involved, are appropriately investigated and resolved, including with documentation in the literature if appropriate. None. The authors declare that they have no relevant financial interests. Received September 29, 2022. Evaluated by 3 external peer reviewers, with direct editorial input from a Statistics/Methods Editor, an Associate Editor, and the Editor-in-Chief. Accepted in revised form March 2, 2022.

Publisher Copyright:
© 2022 National Kidney Foundation, Inc.

All Science Journal Classification (ASJC) codes

  • Nephrology


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