Association between serum zinc levels and stroke severity in adult Japanese patients: A single-center retrospective study.

While the role of zinc in cerebrovascular health is documented, clinical evidence linking serum zinc levels to stroke severity in large cohorts remains inconclusive. This study aimed to investigate the association between serum zinc levels and stroke severity among Japanese patients, specifically controlling for confounders often unavailable in secondary health claims data. A retrospective study was conducted at Tokyo Women's Medical University, Adachi Medical Center. Records of stroke patients (infarct or hemorrhage) admitted between 2022 and 2023 were screened. Inclusion required documented serum zinc levels upon admission. Stroke severity was assessed using the modified Rankin Scale (mRS) and the National Institutes of Health Stroke Scale (NIHSS). Of the 210 patients analyzed, 80% (n = 168) were zinc deficient (Zn < 80 μg/dL). After adjusting for potential confounders, serum zinc levels remained significantly and inversely associated with admission mRS. Specifically, each 1 ug/dL decrease in serum zinc was associated with a 3% increase in the odds of a higher mRS score (p < 0.05). While univariate analysis showed an inverse relationship between zinc and NIHSS (a 0.09-point increase in NIHSS per unit decrease in zinc, crude Beta: -0.09, p = 0.016), this association lost statistical significance after multivariate adjustment, despite maintaining a negative trend (adjusted Beta: -0.55, p = 0.15). Low zinc level is highly prevalent among Japanese stroke patients. Lower serum zinc levels are independently associated with greater functional stroke severity (mRS), a relationship particularly pronounced in patients with cerebral infarction. These findings suggest that zinc status may serve as a relevant biomarker for clinical outcomes in acute stroke management.