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.