Association between serum total calcium levels and acute kidney injury risk in patients with acute pulmonary embolism

Acute pulmonary embolism (APE) is a critical venous thromboembolic condition with a 30-day all-cause mortality rate ranging from 9.2% to 17.4%. Around 20% to 30% of APE patients experience secondary acute kidney injury (AKI), which significantly raises in-hospital mortality. Abnormal serum calcium levels are strongly linked to the development, progression, and prognosis of various diseases. However, there is a lack of systematic research on the relationship between serum calcium levels and the risk of AKI in APE patients. Utilizing the MIMIC-IV 3.1 database, we enrolled 1539 patients diagnosed with APE, confirmed by ICD codes. These patients were categorized based on their serum total calcium (STC) levels, and we calculated albumin-corrected calcium (ACC) as well. To investigate the correlation between STC, ACC, and the risk of in-hospital AKI and severe AKI (KDIGO stage 3), we conducted logistic regression analysis. We employed restricted cubic spline (RCS) plots to examine any non-linear relationships. Additionally, subgroup and sensitivity analyses were performed to evaluate the consistency of our findings. STC was inversely associated with the risk of in-hospital AKI in patients with APE (fully adjusted OR per 1-mg/dL increase = 0.75, 95% CI 0.61–0.89, P = 0.008), and patients with low STC (≤ 8.48 mg/dL) had a significantly higher risk of AKI. In contrast, ACC was not significantly associated with AKI ( P > 0.05). Subgroup analysis showed that the above correlation was stable in populations of different ages, genders, and comorbidities (all interaction P values > 0.05). Sensitivity analysis (excluding patients with missing albumin data and using severe AKI as the outcome) yielded results consistent with the main analysis, supporting the stability of the observed associations. Lower admission STC was associated with a higher risk of in-hospital AKI in critically ill patients with APE, whereas ACC was not significantly associated with AKI. Admission STC may serve as a readily available observational risk marker; however, its incremental predictive value and clinical utility require further evaluation and external validation.