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Background: Hyponatremia, defined by a serum sodium concentration less than 135 mEq/L, is seen in approximately 25% of patients admitted with congestive heart failure (CHF). Hyponatremia on admission has been shown to increase in-hospital mortality and to be an independent predictor of 6month mortality. Prior work has shown that CHF patients with hyponatremia on admission are more likely to be Caucasian. Given its prognostic significance, hyponatremia and its association with patient characteristics warrants further study.

Methods: We queried for unique admissions to Temple University Hospital between 2011 and 2015 with a DRG code of "291-293" to represent a heart failure admission. We identified admissions that had a first sodium lab value after admission available. Chi-square tests were performed to examine association between first Na<135 mEq/L and ethnicity, gender, or ethnic/gender sub-group. Statistical significance was defined as p<0.05.

Results: 884 admissions were identified by ethnicity as either "African-American", "Caucasian (Non-Hispanic)" or "Hispanic". There was no association between first Na<135 mEq/L and ethnicity (Chi-squared=2.31; p=0.31). 976 admissions were identified as either "male" or "female". There was no association between hyponatremia on admission and gender (Chi-squared=1.17; p=0.27). 768 patient admissions could be classified by both ethnicity and gender. The association between hyponatremia on admission and ethnic/gender sub-group did not achieve statistical significance (Chi-squared=9.49; p=0.09).

Conclusion(s): In conclusion, our study demonstrates no statistically significant association between hyponatremia and the patient characteristics ethnicity and gender in a small sample of heart failure admissions. There was a trend toward a lower proportion of "African-American/Female" admissions having hyponatremia.