Clinical determinants of interdialytic weight gain

We recently found a close relationship between high interdialytic weight gain (IDWG) and nutritional parameters, confirming the potential role of IDWG as a marker of calorie and protein intake in hemodialysis patients. In this population, the control of volume status to achieve the "appropriate dry weight" suggests a correlation between blood pressure (BP) and IDWG. The aim of our study was to investigate the clinical determinants of IDWG, particularly regarding sodium balance and nutritional intake, in a cohort of clinically stable hemodialysis patients.

During a 1-year period, we collected clinical and biological data from 32 of 75 patients who underwent dialysis at our Center. To investigate the dietary protein intake, calorie intake, and sodium intake, a dietician assessed a 3-day dietary record. Urea kinetic parameters and interdialytic sodium load were calculated for all patients.

There were 19 men and 13 women with a mean age of 71.3 +/- 13.7 years, 10 of 32 patients were hypertensive, and 14% were diabetics. The mean IDWG calculated during the 3-day interval was 4.5 +/- 1.5%. Simple and multiple regression analysis showed a significant and positive correlation between IDWG and protein catabolic rate (PCR) (P <.0001). In contrast, we did not find any relationship between sodium load, sodium intake, and IDWG, nor between BP and IDWG. In 15 of 32 patients with steadily high IDWG, PCR and calorie intake were significantly higher than in patients with low IDWG (1.3 +/- 0.3 v 0.9 +/- 0.3 g/kg/d, P <.0001, respectively; 28 +/- 7.5 v 21.6 +/- 6.4 cal/kg/d, P <.02, respectively). No changes were found in sodium load and sodium intake.

We confirm that, in hemodialysis patients, a stable IDWG may be a useful clinical marker of adequate calorie and protein intake. IDWG does not seem directly related to BP, even in hypertensive patients, suggesting that additional factors play a role in the control of BP in this population.