The plasma level of brain natriuretic peptide is increased in malnourished hemodialysis patients

Abstract

Background: In hemodialysis (HD) patients, the plasma brain natriuretic peptide (BNP) level is associated with left ventricular dysfunction and patients' survival. Malnutrition is common in HD patients, it is associated with inflammation and contributes to the high incidence of cardiovascular (CV) disease in this setting (malnutrition-inflammation-atherosclerosis syndrome). In a cross-sectional study, we assessed the relationship between predialysis plasma BNP level and nutritional markers in chronic HD patients.

Methods: Of 210 patients receiving HD treatment in our unit, 51 patients who were treated with three times weekly long-hour HD (5-8 h/session) for at least 6 months (mean age 65.8 +/- 15.0 years; F/M ratio 23/28; vintage 71.3 +/- 71.9 months; BMI 24.9 +/- 5.9; session time 6.9 +/- 1.3 h; percentage of diabetic patients 31%) were studied before a mid-week HD session for nutritional markers (plasma albumin 35.3 +/- 3.7 g/l; prealbumin 0.36 +/- 0.09 g/l; CRP 15.3 +/- 14.7 mg/l; nPNA 1.29 +/- 0.29 g/kg/day) and plasma BNP (246.9 +/- 252.2 ng/l, normal <100 ng/l, Bayer(R) kit). The interdialytic weight gain was 2.1 +/- 1.0 kg. In the last 3 months prior to the commencement of the study, the patients' dry weight varied by +0.17 +/- 1.9 kg.

Results: Predialysis plasma BNP levels did not differ according to gender and the presence of diabetes. It was not correlated with age and vintage but was found to be negatively associated with the session time (r = -0.34, p = 0.018). Several nutritional markers were negatively correlated with BNP levels: prealbumin (r = -0.46, p = 0.001), BMI (r = -0.33, p = 0.018), nPNA (r = -0.46, p = 0.002). The plasma albumin relationship with the BNP level was close to significance (p = -0.26, p = 0.070). The 3-month dry weight variation was also negatively correlated with BNP levels (r = -0.34, p = 0.018). With multiple stepwise regression analysis, prealbumin and session time remained significant (respectively p = 0.004 and 0.01). BNP levels were higher in a subgroup of malnourished patients (n = 12) (400 +/- 405 vs. 202 +/- 166 ng/l, p = 0.03) than in patients who did not meet the malnutrition criteria (34 patients). They were not correlated with CRP levels, interdialytic weight gain, or predialysis MAP.

Conclusions: Hence, the plasma BNP level was found to be associated with malnutrition but not with inflammation. This underlines the relationship between nutrition and the CV system in HD patients. The body weight variations associated with malnutrition and the difficulties in assessing and adjusting dry weight may lead to fluid overload, which could explain, in part, these correlations.