Objective:To analyze risk factors for acute cerebral infarction(ACI)combined with hyponatremia in patients aged 70 years and older, in order to improve clinical effects of integrated treatment.Methods:From Jan 2017 to Sep 2018, 324 ACI patients aged 70 years and older admitted to the neurology department of our hospital were enrolled.According to serum sodium levels, patients were divided into the normal serum sodium group(NG, n=284)and the hyponatremia group(HG, n=40). Patients in the HG group were further divided into the mild-to-moderate hyponatremia subgroup and the severe hyponatremia subgroup.Multivariate Logistic regression analysis was used to identify the correlation between risk factors for hyponatremia and prognosis.After one month of treatment, prognosis was assessed by using the Neurological Deficit Score(NDS).Results:There were significant differences between the NG and HG groups in age, the National Institutes of Health Stroke Scale(NIHSS)score, drinking, living alone, long-term bed rest, serum levels of C-reactive protein(CRP), D-dimer, fibrinogen(FIB), total cholesterol(CHOL), triglycerides(TG), high density lipoprotein cholesterol(HDL-C), low density lipoprotein cholesterol(LDL-C), total protein(TP), albumin(ALB), uric acid(UA), apolipoprotein A-1(Apo-A1), potassium, calcium, and phosphorus( P<0.05). Multivariable Logistic regression analysis showed that age( OR=0.917, 95% CI: 0.874-0.962, P=0.000), NHISS score on admission( OR=0.869, 95% CI: 0.783-0.964, P=0.008), drinking( OR=8.001, 95% CI: 3.864-16.567, P=0.000), living alone( OR=0.352, 95% CI: 0.204-0.608, P=0.000), serum CRP( OR=0.975, 95% CI: 0.960-0.990, P=0.001), D-dimer( OR=0.007, 95% CI: 0.001-0.053, P=0.000), CHOL( OR=1.268, 95% CI: 1.058-1.521, P=0.010)and LDL-C( OR=0.357, 95% CI: 0.230-0.552, P=0.000)were independent risk factors, and UA( OR=1.017, 95% CI: 1.013-1.021, P=0.000)was an independent protective factor for ACI combined with hyponatremia in patients aged 70 years and older.Patients in the NG group had better therapeutic effects and prognosis than those in the HG group( P<0.01). Conclusions:Elderly ACI patients aged 70 years and older are prone to hyponatremia.For better clinical effects of integrated treatment, electrolytes should be regularly monitored in elderly patients with related risk factors.