N‑terminal pro‑B-type natriuretic peptide as a marker of hypervolemia and predictor of increased mortality in patients on hemodialysis

INTRODUCTION N‑terminal pro‑B‑type natriuretic peptide (NT‑proBNP) is an established biomarker of heart failure in the general population. However, its diagnostic value is unclear in hemodialysis (HD) patients owing to renal insufficiency.

OBJECTIVES The aim of the study was to establish the usefulness of NT‑proBNP for hydration assessment and the relation of NT‑proBNP to the nutritional state and prognosis of survival. 

PATIENTS AND METHODS In 321 HD patients (206 men; mean age, 65.1 ±21.4 years), we assessed NT‑proBNP levels, overhydration (OHBIA), and the indices of the nutritional state (using a bioimpedance analysis [BIA]) in relation to cardiac troponin T (cTnT), hemoglobin, albumin, total cholesterol (TC), and C‑reactive protein (CRP) levels. The efficacy of HD was assessed using Kt/V, weekly HD dose, and HD session ultrafiltration. The cohort was divided into NT‑proBNP quartiles. Patients with 2 NT‑proBNP measurements were categorized also into change‑over‑time subgroups. A follow‑up lasted for a median period of 23.8 ±26.3 months.

RESULTS Relative OHBIA increased across the NT‑proBNP quartiles (Q1/Q2/Q3/Q4, 1.31% ±2.56%/2.06% ±2.35%/2.92% ±2.97%/4.62% ±4.22%; P <0.0001). NT‑proBNP was also closely associated with other OH parameters. In addition, there was a significant correlation between NT‑proBNP and cTnT (r = 0.55; P <0.0001). Body mass index (BMI) and fat tissue index (FTI) decreased across the quartiles (BMI, 28.5 ±7.7/26.0 ±6.6/25.8 ±5.4/23.7 ±5.5 kg/m2; FTI, 14.4 ±9.0/14.1 ±7.3/12.3 ±6.8/11.6 ±6.1; P <0.001). The highest albumin level was present in Q1 (4.10 ±0.63/3.99 ±0.51/3.90 ±0.62/3.97 ±0.78 g/dl; P = 0.006). The TC level was the lowest in Q4 (190 ±60/169 ±56/173 ±51/153 ±56 mg/dl; P = 0.002). The hemoglobin level decreased across the quartiles (11.44 ±1.25/11.15 ±2.50/10.79 ±1.51/10.45 ±1.67 g/dl; P = 0.0006). The differences in CRP levels and HD‑related parameters were nonsignificant. During the follow‑up, 97 deaths were recorded (11/26/21/39, P <0.0001).

CONCLUSIONS NT‑proBNP seems to be a useful biomarker of hypervolemia in HD patients. Nevertheless, it has to be interpreted with regard to the patient’s individual residual renal function and cardiovascular status.