Incidence of and risk factors for hyponatremia and diabetes insipidus in acute spinal cord injury: a retrospective cohort study

Abstract Background Diabetes insipidus (DI) usually coexists with hyponatremia in patients with acute spinal cord injury (SCI). However, the incidence of DI after acute SCI has rarely been reported. In this study, we aimed to determine the incidence rates and risk factors for these conditions and explore early detection and intervention strategies. Methods Patients with acute SCI who were sequentially admitted to our center between January 2010 and November 2021 were included. Clinical information was extracted from the medical records. Univariate analyses were performed for each potential risk factor. Variables with a P < 0.1 in univariate analysis were included in the multivariate logistic regression analysis, and those with a P < 0.05 were defined as independent risk factors. Results The cohort included 317 patients. One hundred ten (34.7%) of the 317 patients with acute SCI developed hyponatremia, and 60 (18.9%) developed DI. The median time to onset of hyponatremia was 5 days (interquartile range [IQR]: 4–6), and the median time to onset of DI was 7 days (IQR: 6–8). Multivariate logistic regression analysis identified a cervical level of injury and a more severe injury (ASIA A) as strong independent risk factors for hyponatremia (both P < 0.001). Among fracture types, only Type C (compared to Type I) was individually associated with hyponatremia ( P = 0.038), although the overall fracture-type variable was not significant ( P = 0.156). In contrast, for DI, in addition to cervical level and ASIA A injury (both P < 0.001), the fracture-type variable was a significant predictor overall ( P < 0.001), with both Type B ( P = 0.027) and Type C ( P < 0.001) fractures (vs. Type I) being independent risk factors. Conclusion We found a high incidence of hyponatremia (34.7%) and DI (18.9%) in patients with acute SCI. Hyponatremia was mainly associated with higher-level and more severe SCI, with an added risk observed in fracture type C, whereas DI was associated with higher-level SCI, more severe injuries, and fracture types B and C. Our study highlights the interconnected nature of hyponatremia and DI as manifestations of acute SCI. Future research should adopt a unified pathophysiological framework that integrates these findings to better understand the underlying mechanisms.