Hospitalization for intercurrent illness frequently disrupts the nutritional status of hemodialysis (HD) patients and jeopardizes the dry weight prescription. We report in this study the evolution of brain natriuretic peptide (BNP), blood pressure and body weight in hospitalized patients and the relationship between BNP plasma level and nutritional and inflammation parameters. We have studied 42 patients requiring hospitalization (F/M: 18/24; 72.5±12.5years old; 19/42 with diabetes). The plasma BNP levels at baseline, during hospitalization (BNP-Hosp), and in the recovery phase were compared. Predialysis and postdialysis blood pressure and postdialysis body weight were recorded and compared. BNP-Hosp increased significantly when compared with BNP levels at baseline, from 421±647.2pg/mL to 1584±1584.4pg/mL (P<0.0001). Brain natriuretic peptide decreased from 1223±1342.1pg/mL during hospitalization to 616±892.1pg/mL after discharge (P=0.005). The BNP-Hosp was positively correlated with C-reactive protein (P=0.003) and negatively correlated with serum prealbumin (P=0.0001) and albumin (P=0.0001). The postdialysis body weight prescription decreased from 71.0±15.7kg at baseline to 70.5±15.4kg during hospitalization and to 67.8±14.4kg 4months after discharge (P=0.0032). Our study displays clearly the significant changes of plasma BNP levels occurring during intercurrent events. Fluid overload triggered by inflammation-associated catabolism and the lag time for dry weight adjustment is the cause of this finding. Hence, plasma BNP level may be used as a marker of fluid overload in patients with intercurrent events and may allow efficient dry weight adjustment. We cannot rule out an effect of inflammation on BNP synthesis. © 2011 The Authors; Hemodialysis International © 2011 International Society for Hemodialysis.