Dysmagnesemia with acute kidney injury among older adults: clinical characteristics and prognostic importance

Purpose: The relationship between dysmagnesemia and all-cause mortality probability in individuals with acute kidney injury (AKI) have not been investigated. In this study, we evaluated the correlation of varying magnesium levels with mortality in older adults undergoing AKI.

Patients and methods: Older adults receiving treatment at the Chinese PLA General Hospital between 2007 and 2018 were retrospectively recruited. All-cause mortality was evaluated at four preset magnesium concentrations: <0.8, 0.8-0.9, 0.9-1.0, and ≥ 1.0 mmol/L. Using multivariable-adjusted Cox assessment, the all-cause mortality risk was approximated by setting the reference magnesium concentration at 0.8-0.9 mmol/L.

Results: Totally 744 participants were enrolled, whose median age was 88 years, with most of them being male (94.2%). Among them, 184 patients were assigned into the < 0.8 mmol/L group, 156 into the 0.8-0.9 mmol/L group, 206 into the 0.9-1.0 mmol/L group, and 198 into the ≥ 1.0 mmol/L group. After 28 days, the mortality rates in the four strata were 26.6, 17.9, 17.5, and 37.4%, respectively. The corresponding mortalities after 90 days were 42.4, 23.7, 26.7, and 45.5%, respectively. Compared with patients who had magnesium levels of 0.8-0.9 mmol/L, those with magnesium levels < 0.8 mmol/L (P = 0.048), and ≥ 1.0 mmol/L (P < 0.001) exhibited higher 28-day mortalities. Significant correlations also showed that patients with magnesium levels < 0.8 mmol/L (P = 0.017) and ≥ 1.0 mmol/L (P < 0.001) were significantly related to the increased 90-day mortality.

Conclusion: Magnesium levels outside the interval of 0.8-1.0 mmol/L were related to the higher risks of 28- and 90-day mortalities among older adults with AKI.