The use of B-type natriuretic peptide to assess volume status in patients with end-stage renal disease

Background Although B-type natriuretic peptide (BNP) levels correlate with volume overload in congestive heart failure, its usefulness in patients with renal dysfunction has been questioned. A simple test to estimate volume overload and assist in the management of dry weight in hemodialysis (HD) patients would be useful. Methods Thirty-nine patients—aged 64 ± 2 years (mean ± SEM), male-female ratio of 37:2—undergoing HD thrice weekly for at least 30 days were studied. Samples were collected at the start and end of each of 3 consecutive HD sessions. Pre- and postsession weights and blood pressures were recorded. Left ventricular ejection fractions were obtained from echocardiograms performed within 1 year of enrollment. The first session was the dialysis session after a 72-hour interdialytic period, whereas the second and third sessions were after a 48-hour period. Plasma volume changes were measured in a subset of 13 patients. Results Pre- and postdialysis BNP levels for each of the 3 sessions were 434 and 343 pg/mL, 347 and 231 pg/mL, and 249 and 202 pg/mL, respectively. The values for body weights were 82.6 ± 3.6 and 78.6 ± 3.5 kg, 81.5 ± 3.6 and 78.2 ± 3.5 kg, and 81.5 ± 3.46 and 78.3 ± 3.5 kg, respectively. The values of mean systolic blood pressures were 150 ± 4 and 134 ± 3 mm Hg, 142 ± 4 and 134 ± 4 mm Hg, and 142 ± 4 and 131 ± 4 mm Hg, respectively. The values for mean diastolic blood pressures were 81 ± 2.5 and 70 ± 2.4 mm Hg, 74 ± 2.4 and 72.1 ± 2.2 mm Hg, and 76 ± 2.9 and 72 ± 2.9 mm Hg, respectively. There was no correlation between changes in intradialytic BNP values and other measured parameters. Plasma volume changed minimally during dialysis. Conclusions Values of BNP are elevated in patients with end-stage renal disease and decline after each dialysis session. Over the course of a week, BNP levels gradually declined irrespective of changes in weight or blood pressure. The lack of correlation between changes in BNP and changes in measured clinical parameters is partly explained by a lack of a significant change in plasma volume. The highest BNP values were seen in patients with systolic dysfunction.