The prevalence of hyponatremia and its association with mortality of acute ischemic stroke: a systematic review and meta-analysis

Objectives: Clinical management of acute ischemic stroke (AIS) can be significantly impacted by underlying factors such as electrolyte imbalances, most notably hyponatremia. Literature on definition, chronologicity, and impact of hyponatremia on outcomes of AIS is diverse. We aimed to assess the prevalence of hyponatremia and its influence on mortality of AIS patients. Methods: A systematic literature review was conducted from inception to 1 December 2025, searching PubMed, Web of Science, and Embase for human subject research studying AIS and hyponatremia. Hyponatremia proportions and mortality risk ratios were pooled using random-effects models. Between-study heterogeneity was assessed using I², and sensitivity analyses were employed to assess robustness. Results: Among 4665 abstracts, 26 studies with a total of 21,481 patients were included. The pooled prevalence of hyponatremia in AIS was 22.31% (95% CI 16.67–28.50%) with mortality reported across nine studies showing increased frequency for hyponatremic patients (55.1% vs 27.6%) and risk ratio of 2.11 (95% CI 1.39–3.19, p = 0.0032). Conclusion: Our meta-analysis demonstrated significant data heterogeneity in the literature for hyponatremia definition, prevalence, and mortality in patients with AIS. Despite likely underreporting due to these factors, our results support high prevalence of hyponatremia and association with increased rates of mortality.