Khoury J, et al. - In this retrospective analysis of patients with first hospitalization with the primary diagnosis of heart failure (HF) (n=4,768, 2567 were male (53.8%); the mean age was 74.7 ± 12.7 years), researchers determined how mortality was influenced by blood urea nitrogen (BUN) variation during hospitalization. According to the findings, BUN (both on admission and on discharge) was identified as a prognostic predictor in HF patients; however, the worst prognosis was reported for patients with elevated levels both on admission and on discharge. A worse prognostic predictor was worsening or lack of improvement in BUN during hospitalization. The alterations in BUN during hospitalization in HF are discussed for the first time in this study.