The Prevalence Of Hospitalized Patients With Hyponatremia And Cause Analysis

[Objective]Hyponatremia is the most common electrolyte abnormality and it is associated with increased morbidity and mortality. The aim of the study was to investigate the prevalence and the underlying causes of hyponatremia in hospitalized patients, and futher the association between hyponatremia and mortality.[Methods]A descriptive, retrospective hospital record study was performed. A database search was conducted for all patients older than14y presenting to Zhou Shan hospital from Jan2014to Apr2014. Total552patients (320Male and205Female;264patients aged≥60y and261patients aged<60y) with a P-Na-value<135mmol/L on the first sodium determination were identified by a laboratory database search. Patients were divided into three groups based on the severity of hyponatremia (Group1:mild hyponatremia with P-Na130-135mmol/1, Group2:moderate hyponatremia with P-Na125-129mmol/1, Group3:severe hyponatremia with P-Na<125mmol/1).Detailed medical history and outcomes were recorded. Laboratory data including serum sodium, potassium, serum osmolality, kidney function, hematocrit and so on at admission, as well as serum sodium levels three days before hospital discharge were all collected. The differences of clinical characteristics and underlying causes of hyponatremia were analyzed among the three groups, and a binary logistic regression model was used to explore the association between hyponatremia and mortality.[Results]1. The prevalence of hospitalized patients with hyponatremia was5.26%(552/9989), and which was increased to6.1%(264/4334) in elderly patients. The prevalence of mild, moderate and severe hyponatremia was3.46%,1.35%and0.44%in552hyponatremic patients, respectively. The prevalence of mild, moderate and severe hyponatremia was3.65%,1.96%and0.49%in elderly hyponatremic patients, respectively.2. Two most common causes of mild hyponatremia were malignant tumor and infectious diseases, whereas moderate and severe hyponatremia were found in patients with malignant tumor, cerebral hemorrhage and infectious diseases. In the subgroup of elderly hyponatremic patients, malignant tumor and infectious diseases were the most common causes of hyponatremia regardless of the severity of hyponatremia.3.13.7%and3.8%of552hyponatremic patients were diagnosed with SIADH and CSWS, and17.4%and4.2%of264elderly hyponatremic patients were diagnosed with SIADH and CSWS. Moderately severe hyponatremia was more likely to occur in patients with natriuretic treatment.4. The cure and improvement rates of hyponatremic patients were shown to be70.1%and10.8%, and the ineffeciency and mortality were14.5%and4.6%. Patients with moderate hyponatremia had a significantly lower cure rate, but a significantly higher mortality than those of patients with mild hyponatremia (P<0.01).However, there were no significant differences in cure and improvement rates, as well as inefficiency and mortality between patients with moderate and severe hyponatremia. In multivariable-adjusted models, patients with moderate hyponatremia or severe hyponatremia had an increased mortality in hospital versus those only with mild hyponatremia (OR6.459,95%confidence interval (CI):2.360-17.683, P<0.001or OR4.8,95%CI:1.110-20.754, P=0.036).[Conclusions]Hyponatremia was common in hospitalized patients. Malignant tumor, infectious diseases and cerebral hemorrhage, complicating with SIADH and CSWS were primary causes of hyponatremia, while the use of natriuretic increased the risk of moderately severe hyponatremia. The relationship between moderately severe hyponatremia and mortality was pronounced in hospitalized patients.