CAMELIA CRISTINA DIACONU, MARIA MANEA, MIHAELA ADELA IANCU, ANA MARIA ALEXANDRA STANESCU, BOGDAN SOCEA, DAN ARSENIE SPINU, DRAGOS MARCU, OVIDIU GABRIEL BRATU HYPONATREMIA IN PATIENTS WITH HEART FAILURE: A PROGNOSTIC MARKER Due to the high prevalence of cardiovascular diseases and better treatment strategies, with increased survival, heart failure is a condition with increasing prevalence, especially in developed countries. Heart failure patients often present electrolytic disorders, the most frequent one being hyponatremia. The objective of the study was to evaluate the frequency of hyponatremia in patients with chronic heart failure hospitalized in the Internal Medicine Clinic of the Clinical Emergency Hospital of Bucharest and to assess the clinical and paraclinical correlations, as well as prognostic implications of hyponatremia in these patients. We performed an observational retrospective study on 400 chronic heart failure patients hospitalized between January 1st 2014 and August 31st 2015. From these patients, 60 patients have been diagnosed with hyponatremia (defined as a serum natrium <135 mEq/L) and represented our group of study. The values of the serum natrium at admission in the study group ranged between 110-132 mmol/L. Most patients had advanced heart failure, according to NYHA classes’ classification. The proportion of patients discharged with persistent hyponatremia was 48.33%, lower than the patients discharged with corrected serum sodium (51.67%), indicating an effective treatment of hyponatremia during hospitalization. The mortality rate during hospitalization in patients with corrected hyponatremia was 8.33%, smaller than the mortality rate in patients with persistent hyponatremia despite the correct administration of hydroelectrolytic rebalancing treatment (18.33%). Persistent hyponatremia may be considered a marker of a poor prognosis in hospitalized heart failure patients.