Mild hyponatremia discovered within the first 24 hours of ischemic stroke is a risk factor for early post stroke mortality

Background. Comorbidities, complications and laboratory abnormalities are common in stroke patients. One of the common problems is hyponatremia (serum sodium (Na) level <135 mmol/L), but the relationship between hyponatremia and the prognosis in patients with stroke is not well understood. Objectives. The aim of this study was to investigate the prevalence and severity of hyponatremia, as well as its impact on prognosis in stroke patients on admission to hospital. Material and methods. The study involved the analysis of the first measurement of the Na level after the admission and its correlations with comorbidities, the scale of clinical assessment of stroke severity (NIHSS), the size and location of the stroke, and mortality. A retrospective study was conducted on 502 patients (among them 263 women) admitted to the hospital on stroke onset (440 ischemic stroke (IS) and 62 hemorrhagic stroke (HS) patients). The post-stroke mortality was defined as early if death occurred within 30 days. Results. Hyponatremia was found in 18.4% of patients with IS and 25.8% of patients with HS, irrespective of age and gender. Hyponatremia is an independent prognostic factor of mortality in people with IS (p=0.003). Na levels were lower in IS patients who died than in those who remained alive (134.8 +/- 4.99 mmol/L vs 136.6 +/- 3.01 mmol/L; p = 0.02). Higher mortality rate was observed among IS patients under 75 years of age and Na level <= 132 mmol/L. In patients with IS, hyponatremia correlates with NIHSS (p = 0.005) and the size and location of the stroke (p = 0.002). Conclusions. Hyponatremia is more frequently observed in patients with HS than IS. Mild hyponatremia is already known to be an independent prognostic factor in the mortality of people with IS and it may also have value as a prognostic factor in the mortality of the IS population. In a patient with a suspected stroke, there is a need to control electrolyte levels at the onset of the stroke, especially in patients with comorbidities, irrespective of age.